profibus troubleshooting & maintenance
DESCRIPTION
profibusTRANSCRIPT
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
Copyright (c) 1999-2011 PROCENTEC. All rights reserved. 1
Title slideTitle slide
Copyright © 1999-2011 PROCENTEC. All rights reserved. www.procentec.com
1Troubleshooting and Maintenance
PROCENTEC PROCENTEC –– www.procentec.comwww.procentec.com
Is a completely independent company(offices and local support in The Netherlands, Germany and Singapore).
Concentrates products and services on PROFIBUS and PROFINET technology.
Operational areas: Europe, Asia, Middle-East and North America.
Core activities:
Fi ld k ( it t bl h ti d t)
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2
Field work (on-site troubleshooting and support)
Manufacturing of network components and tools
Certification (products and installations)
Training
3.3
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Subjects (1)Subjects (1)
Introduction
Basic principles OSI model Topology Addressing Communication relations Token passing Baudrates
RS 485 and PROFIBUS DP The technology of RS 485 Signaling Cable specification, construction and variants Topology (cable lengths, spur lines) DB9 and M12 connector
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DB9 and M12 connector Termination Repeaters
Grounding and shielding External influences on the bus cable IEC 61000-5-2 Grounding and shielding between cabinets Distances between high voltage cable
Subjects (2)Subjects (2)
Basic principles of data communication technology Impedance, delays Attenuation, skin effectReflections
Test- and measurement tools Handheld tools Oscilloscopes Busmonitors
Busparameters
PROFIBUS PA DP/PA couplers and links Topology Cable specifications
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Cable specifications Terminators and connectors Parameters and profiles
Strategy of fault finding
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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A few words of some inexperienced engineers and marketeers:
‘The cabling is the easiestpart of bus systems…..’
‘Yeah right!!!!!’
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The engineers and maintenance technicians who have just stepped out of the 4-20 mA technology had to understand a lot of new terms which makes the step to field busses very hard……
A change in working and thinking for the entire organizationA change in working and thinking for the entire organization
y
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Not understanding these topics is not good for the ‘Bus business!’
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Change in technology means change in tools!Change in technology means change in tools!
AD
DA
ADCPU CPU4..20 mA
Process Controlconventionalanalog
A D A
AD
DA
ADCPU CPU
HART4..20 mA
smart signal
smart
digital
analog + digital (hybrid)
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AD CPU CPU
A multi-meter can not be used with digital technology.
digitaldigital
Fieldbus 0 1 0 1 0
What can happen in a running installation?What can happen in a running installation?
InternetInternet
OS OS
Programming faultsProgramming faults
PROFIBUS DP/PA
PROFINET / Ethernet / TCP-IP
PLC
RS 485-IS or MBP-ISRS 485 or FO
ManufacturingManufacturing ProcessProcess
PROFIBUS DP
IPC
Programming faultsProgramming faults
Connection faults, reflections, wire breaks, short circuitsConnection faults, reflections, wire breaks, short circuits
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AS-Interface
Instrument or I/O failureInstrument or I/O failureInstrument removalInstrument removal
?Faulty addressFaulty address
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Confusion about the LEDs!Confusion about the LEDs!
Problems can be very difficult to diagnose without the correct tools and a systematic approach. Intermittent faults can be particularly difficult.
The main problem is that the devices that are most affected are often at the
Cause of reflection, e.g. spur line
T T
The main problem is that the devices that are most affected are often at the opposite end of the segment from the source of the reflection!
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Bus fault
9
1.0
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PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Basic principles
Basic principlesBasic principles
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1.0
Overview of the PROFIBUS application layersOverview of the PROFIBUS application layers
PROFIsafePROFIBUS PA
PROFIBUSDP
PROFIdriveMarket name
Basic principles
Profile
PA
FDL + DP
DP
“PROFIsafe” “PROFIdrive”“PA Devices”Nothing
Communicationtechnology
FDL + DP FDL + DP FDL + DP
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Transmissiontechnology
MBP-ISRS 485 RS 485 RS 485
2.0
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Fiber OpticFiber Optic
RS 485RS 4852-wire CU-cable for general purposes
PROFIBUS supports 3 transmission mediaPROFIBUS supports 3 transmission media
Basic principles
Fiber OpticFiber OpticFor highest EMC protection
and wide distances
Fiber optic cable
Coupler CouplerMBPMBP--ISIS2-wire CU-cable with the option for
power over the bus and Ex-protection
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Fiber optic cable
1.0
PROFIBUS is a PROFIBUS is a master/slave master/slave networknetwork
To create hierarchy in the network, PROFIBUS defines 2 types of devices: active (masters) and passive (slaves) devices.
Basic principles
master
commands
responses
network
slave
0 1 0 1 00 1 0 1 0
0 1 0 1 00 1 0 1 0
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At least 1 master is mandatory.
PROFIBUS networks allow multiple masters.
In total 127 devices can be addressed (masters + slaves).
3.1
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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MasterMaster
Basic principles
This station is permanently responsible for the control of the network. The station can generate messages, send these to slaves and interpret responses of slaves.
Examples
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p PLC’s DCS systems PC’s
2.0
SlaveSlave
Basic principles
This station can interpret messages of a master and dependent on the interpretation, generate responses and send them to the specific master.
Slaves are NOT able to send messages on its own initiative.
Examples: Remote I/O
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Sensors and actuators
There are also PLC systems available which have slave functionality. They are slave on DP, but can control I/O locally.
2.0
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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TopologyTopology
PROFIBUS communicates over a two wire bus structure.
sendinglisten,
taking over and
Basic principles
1
taking over andanswering
9
5 43
listen
1170 1 0 1 0
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Devices are addressed through a network address (0..126).
Devices are coupled in parallel to the bus.
Devices have no fixed position on the bus.
Devices can be removed and inserted during operation.
listen listen
2.0
Assigning the address by dipswitchesAssigning the address by dipswitches
Significance 1 2 4 8 16 32 64
Basic principles
OFF
ON
1 2 3 4 5 6 7 8
Software
Hardware
Address = 1 + 0 + 4 + 0 + 0 + 0 + 0 = 5
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After changing the hardware address, most of the time the device has to be powered down/up.
2.0
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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When devices do not have dipswitches, the address can be assigned with the PROFIBUS “Set Slave Address” command. A number of tools are available to fulfil this function.
Assigning the address by softwareAssigning the address by software
Basic principles
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With PROFIBUS PA considerably more devices do not have dipswitches.
With PROFIBUS PA considerably more devices do not have dipswitches.
1.0
PROFIBUS address mapPROFIBUS address map
0
1..2
Service-, diagnosis- and programming tool
Masters (class 1)
Basic principles
Most configuration tools block address 0 and 126 for slaves. Address 126 is a default address for slaves with software address settings. Add 127 i b d t dd ( l i ibl ith b it )
3..125
126
Slaves (total 123 or 124)
Address for: “Set Slave Address”
127 Broadcast address
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Address 127 is a broadcast address (only visible with a busmonitor).
Maximum 124 DP slaves per bus!!!!!!!
2.0
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Medium access by token passingMedium access by token passing
Active stations, master devices
Basic principles
PROFIBUS protocol
,
PLC DCSPC
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Polling of passive stations (slave devices)
1.0
PROFIBUS offers the user the possibility to choose from 10 transmission speeds (RS 485).
Transmission speed (baudrate)Transmission speed (baudrate)
Basic principles
Remarks: The transmission speed determines the maximum cable length and vice versa.
The transmission speed has to be set identically at all the masters on the same bus.
Most slaves detect the baudrate automatically.
Because of economic and technical reasons some products do not support all
9,6 19,2 45,45 93,75 187,5 500 1500 3000 6000 12000 kbps
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Because of economic and technical reasons some products do not support all transmission speeds.
Some older products do not support 45,45 kbps.
2.1
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Application layersApplication layers
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1.0
At this moment the application layer of the PROFIBUS family consists out of 2 standards + profiles: DP (DP-V0, DP-V1, DP-V2) PA
Application layersApplication layers
PA
IEC 61158
e P
rofi
les
atio
n P
rofi
les
Process Automation
PROFIBUS PA
Factory Automation
PROFIBUS DP
General PurposeAutomation
PROFIBUS FMS
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Dev
ice
Ap
plic
aPROFIBUS PAMBP-IS
- Power over the bus - Intrinsic safety
PROFIBUS DPRS 485 / FO
- Plug and play- Efficient and cost effective
Speed
PROFIBUS FMSRS 485 / FO
- Large variety of applications- Multi-master communication
Universal Application oriented
3.1
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PROFIBUS DP
PROFIBUS DPPROFIBUS DP
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1.0
Decentralized Peripherals (DP)Decentralized Peripherals (DP)
Based on high speed data exchange between a central controller (master) and a number of slaves. The data transfer is cyclic.
PROFIBUS DP
The slaves are polled every cycle with the same priority.
Maximum 244 bytes input and 244 bytes output per slave.
Maximum baudrate: 12 Mbps.
Slave configuration and parameters are set from the master side.
Extended diagnostic possibilities.
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124 slaves can be put in Data Exchange.
32 stations on one copper segment (RS 485).
2.3
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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PROFIBUS DP systems consist out of:- multiple masters (Class 1 or 2)- 1 to max. 124 DP Slaves
PROFIBUS DP Multimaster systemPROFIBUS DP Multimaster system
DP master
PROFIBUS DP
DP master(class 2)
DP master(class 1)
DP master(class 1)
PLC
PROFIBUS DP
PC
CNC
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distributed inputs and outputs distributed inputs and outputs
DP slaves
1.0
Example of a DP master configuration toolExample of a DP master configuration tool
PROFIBUS DP
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2.0
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Request FrameRequest Frame
2
Request Frame
3
Request Frame
. x
Principle of data exchange with DP (cyclic)Principle of data exchange with DP (cyclic)
PROFIBUS DP
DP
sla
ve 1
DP
mas
ter
imm
edia
tere
spo
nse
trailer Output data header
Response Frame
trailerInput dataheader
imm
edia
tere
spo
nse
trailer Output data header
Response Frame
trailerInput dataheader
DP
sla
ve 2
imm
edia
tere
spo
nse
trailer Output data header
Response Frame
trailerInput dataheader
DP
sla
ve 3
imm
edia
tere
spo
nse
trailer Output data header
Response Frame
trailerInput dataheader
DP
sla
ve n
r.
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Per slave:Max. 244 bytes output dataMax. 244 bytes input data
Per slave:Max. 244 bytes output dataMax. 244 bytes input data
1.1
The handling of all the slaves is called a cycle. The required time is dependent of:- the baudrate;- the number of slaves; - the net data;
The handling of all the slaves is called a cycle. The required time is dependent of:- the baudrate;- the number of slaves; - the net data;
Rules for PROFIBUS message transactionsRules for PROFIBUS message transactions
Correct transaction, the slave replies within the Slot Time.
Correct transaction, the slave replies within the Slot Time.
Master Slave(s)Output data
Input dataIn this example the retries of the master have been set to 3!
In this example the retries of the master have been set to 3!
PROFIBUS DP
the Slot Time.the Slot Time.
Because of no / illegal / corrupted replies, 2 retries but eventually OK (recovery).
Because of no / illegal / corrupted replies, 2 retries but eventually OK (recovery).
3-Retries ns ccessf l
3-Retries ns ccessf l
Output data
Output data - RetryOutput data - Retry
Input data
Output dataOutput data - RetryOutput data - Retry
ProfiTrace Statistics- Worst case sequence = 2- Total retries = 2
ProfiTrace Statistics- Worst case sequence = 2- Total retries = 2
ProfiTrace StatisticsProfiTrace Statistics
have been set to 3!have been set to 3!
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unsuccessful.The slave is lost!unsuccessful.The slave is lost!
Every cycle a SYNC to establish contact with the lost slave.
Every cycle a SYNC to establish contact with the lost slave.
p yOutput data - Retry
Output data - Next slave
Get diagnostics or Output data - SYNC
Get diagnostics or Output data - SYNC
- Worst case sequence = 3- Total retries = 5- Worst case sequence = 3- Total retries = 5
ProfiTrace Statistics- Syncs are incrementedProfiTrace Statistics- Syncs are incremented
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PROFIBUS PAPROFIBUS PAPROFIBUS PAPROFIBUS PA(part 1)(part 1)
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1.0
Process Automation (PA)Process Automation (PA)
Communication, according to the intrinsic safe standard MBP-IS. The protocol is based on PROFIBUS DP + DP-V1, but the electrical characteristics are changed. This standard is used in the (petro)chemical and nutrition industry.g (p ) y
Replacement for 4..20 mA installations.
Suitable for chemical industry and process control.
Power supply and communication over two wires (31,25 kbps).
Profiles define parameters which are accessible by engineering tools (DP-V1
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Profiles define parameters which are accessible by engineering tools (DP V1
communication).
The profile allows instrument exchange.
Certification according to the FISCO model.
2.3
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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PROFIBUS PA
=PROFIBUS DP/DP-V1
The principle of PROFIBUS PAThe principle of PROFIBUS PA
x+PROFIBUS DP
PROFIBUS DP/DP-V1
+Intrinsic safe communication properties
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PROFIBUS PA
J
1.0
Overview of the PROFIBUS familyOverview of the PROFIBUS family
InternetInternet
OS OS
PROFIBUS DP/PA
Ethernet / TCP-IP / PROFINET
PLC
RS 485-IS or MBP-ISRS 485 or FO
ManufacturingManufacturing ProcessProcess
PROFIBUS DP
IPC
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AS-Interface
2.1
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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RS 485 and PROFIBUS DP
RS 485 and PROFIBUS DPRS 485 and PROFIBUS DP
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1.1
RS 485RS 485 Baudrates from 9.6 kbit/s to 12 Mbit/s
Shielded twisted pair cable
32 devices per segment
RS 485 and PROFIBUS DP
Distance: 12 Mbit/s = 100 m; 1.5 Mbit/s = 200 m; < 187.5 kbit/s = 1,000 m
Distance extendable with repeaters
MBPMBP--ISIS Fixed baudrate of 31.25 kbit/s
Intrinsic safety (option) and power over the bus
Shielded twisted pair cable
Distance up to 1,900 m per segment dep. on Ex-class and power consumption
10 32 devices per segment dep on Ex class and power consumption
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10-32 devices per segment, dep. on Ex-class and power consumption
Fiber opticsFiber optics Baudrates from 9.6 kbit/s up to 12 Mbit/s
Monomode, Multimode, plastic or PCS/HCS fibers are available
Distance extendable with repeaters up to 100 km
1.0
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Design specificationsDesign specifications
What are the critical points when designing RS 485 segments?
Spur lines
RS 485 and PROFIBUS DP
Shielding & Grounding
Spur lines
Powered Termination
Cable length
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Max. 32 devices
2.2
The technology of The technology of RS 485RS 485
TTL/CMOSR T
DeviceTTL/
CMOSR T
DeviceTTL/
CMOSR T
Device
Maximum 32
RS 485 and PROFIBUS DP
Z Z Z
220E
+5V
390E
220E
+5V
390E i
A
B
Maximum 32devices.
+/-U
R = 30k..200kC < 35pF
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6. Pull-up/down resistors are essential for the basic current.
GND
390E
GND
390E
1. Sending data by means of current and polarity change.
2. The receivers read the current flow by input impedance (Z).
A
4. The differential voltage should be +/-200mV or more. In reality in the range 4 to 5V.
3. Because of the parallel resistors, a maximum of 32 devices is allowed on a segment.
5. Termination on the end of the cable.
1.1
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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RS 485 SignalsRS 485 Signals
RS 485 and PROFIBUS DP
Line A (2 x Volt)Line A (2,x Volt)
Line B (2,x Volt)
Differential VoltageB A (4 x Volt)
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B – A (4,x Volt)
1.0
More examples of signalsMore examples of signals
RS 485 and PROFIBUS DP
Acceptable signals(Good communication)
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( )
Heavy noise interference(Communication errors)
Partial noise interference(Good communication)
1.0
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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TopologyTopology
1. Cable to next device. Spurs have to be as short as possible.
3. When the baudrate is 1500 kbps or higher, minimum 1 meter cable between 2 devices.
4. Termination (powered) at both ends.
RS 485 and PROFIBUS DP
Master SlaveSlave Slave Slave Slave Slave
Maximum 32 devices
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power power power power power power power
2. The devices have their own power supply.
2.1
Plug with termination OFF.
Plug with termination ON.
1 meter rule with 1,5 Mbps or higher 1 meter rule with 1,5 Mbps or higher baudratesbaudrates
30 pF 30 pF
Each certified device has a small connection capacitance (typically 30 pF) and causes a minimal reflection because of the small short circuit that appears
RS 485 and PROFIBUS DP
30 pF p ppwhen bits change to another level. This is absolutely normal!
However when connected closely together the capacitances ADD and can produce a reflection that alters the bit level and corrupts messages.
‘Scope trace:-
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Separating devices with at least 1 m cable, introduces a small signal delay between the devices, so the reflections don’t add!
1.0
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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These two cables could cause data communication problems (the 1 meter rule).
These two cables could cause data communication problems (the 1 meter rule).
Example Example –– Problems with the 1 meter ruleProblems with the 1 meter rule
RS 485 and PROFIBUS DP
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1.1
Example Example –– Solution for the 1 meter ruleSolution for the 1 meter rule
RS 485 and PROFIBUS DP
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A strategic placement automatically takes care of the 1 meter rule.
3.0
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Baudrate (kbit/s)
Segment length ( )
9.6
1200 1200
19.2 1500 6000 120003000500187.593.7545.45
100100100200400100012001200
Cable length versus BaudrateCable length versus Baudrate
RS 485 and PROFIBUS DP
(m)
Segment length (feet)
3940 3940 3283283286561310328039403940
3 baudrate transitions in which the cable length reduces with more than 50 %.
3 baudrate transitions in which the cable length reduces with more than 50 %.
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2.1
These lengths are defined for 1 segment with 32 bus loads!These lengths are defined for 1 segment with 32 bus loads!
Cable T-splice orjunction box
SSpurspurs
RS 485 and PROFIBUS DP
Device
Total length of allstubs max. 6,6 mwith 1500 kbps.
junction box
Try to avoid spurs with RS 485.Capacitance of connectors and
junction boxes is not well defined!
Try to avoid spurs with RS 485.Capacitance of connectors and
junction boxes is not well defined!
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Device
Total 6,6 m with 1500 kbps (capacity of spurs = 0,2 nF) Total 20 m with 500 kbps (capacity of spurs = 0,6 nF) Total 33 m with 187,5 kbps (capacity of spurs = 1,0 nF) Total 100 m with 93,75 kbps (capacity of spurs = 3,0 nF) Total 500 m with 9,6 and 19,2 kbps (capacity of spurs = 15 nF)
2.2
The length is a sum of all the spurs in the segment!
The length is a sum of all the spurs in the segment!
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Example Example -- Spur linesSpur lines
RS 485 and PROFIBUS DP
70 cm
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More than 17 devices
1.0
Cable specificationsCable specifications
Standard PROFIBUS DP cables must comply to the following specifications:
RS 485 and PROFIBUS DP
Parameter Value
System specification
Low
Low
High?
System specificationWires 2 (twisted)
Impedance 150 Ohm (3 to 20 MHz)
Capacity ≤ 30 pF/m
Loop resistance ≤ 110 Ohm/km
Wire diameter ≥ 0.64 mm
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g
High?
Lower shielding resistance -> better EMC quality.
4.0
Wire area ≥ 0.32 mm2
Shielding resistance ≤ 9.5 Ohm/km Low
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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The A and B line are green and red:
Cable construction and wire colorsCable construction and wire colors
RS 485 and PROFIBUS DP
A-line
B-line
TXD-N
TXD-P
1
2
-
+
green
red
4. Foil for frequencies above 50 MHz.
1. A-line (green) andB-line (red).
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2.0
3. Braid for frequencies up to 50 MHz.
2. “Tubes” for a round cable.
All kinds of cables are available for areas in which the standard PROFIBUS cable cannot be used.
Cable typesCable types
RS 485 and PROFIBUS DP
Robust cableFlexible cable
Trailing cable
Robust cable
Food cable
Ground cable
Trailing cable
Festoon cable
Fire and heat cable
Flexible cable
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FRNC cable
Shipboard cableFestoon cable Food cable
Robust cableHybrid cable
2.0
Flexible cable
Shipboard cable
Hybrid cable
Rodent protection cable
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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ConnectorConnectorss
The connector technology is NOT defined.
Manufacturers determine the implementation of the connector
RS 485 and PROFIBUS DP
Manufacturers determine the implementation of the connector.
The PROFIBUS standard describes some recommended implementations: DB9 and M12.
If a manufacturer selects a connector which is described in the standard, then it has to be implemented according to the standard.
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1.0
For devices with a DB9 connector, standardized plugs are available for chaining the bus.
DB9 connectorDB9 connector -- StructureStructure
RS 485 and PROFIBUS DP
Versions are available on which an extrapiggy back connector is implemented. It’s
recommended to put one on every segment
Versions are available on which an extrapiggy back connector is implemented. It’s
recommended to put one on every segment
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52
recommended to put one on every segment for maintenance purposes.
recommended to put one on every segment for maintenance purposes.
2.2
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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DB9 connector DB9 connector –– Pin layoutPin layout
The pin-layout of the DB9 connector is defined as follows:
Pin nr. Signal Description
RS 485 and PROFIBUS DP
1
2
3
4
5
6
7
8
M24
B-Line
CNTR-P
DGND
VP
P24
A Line
Shield <NOT USED ANYMORE>
Ground for +24 V output voltage
RxD/TxD-P Receive/Transmit data - plus
Repeater control signal (direction control), RTS signal
Digital ground
Supply voltage (+5 V)
Output voltage +24 V
RxD/TxD N Receive/Transmit data minus
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53
8
9
A-Line
CNTR-N
RxD/TxD-N Receive/Transmit data - minus
Repeater control signal (direction control)
2.1
: This signal is mandatory.
Shield (Metal casing of the connector)Shield(10)
DB9 connector DB9 connector –– Connection methodConnection method
The method of connecting the cable is very important. When termination is enabled, the second channel is disconnected.
RS 485 and PROFIBUS DP
Shield
T = on T = off
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54
Cable Insulation
1.3
The left plug has the termination ON, the second channel can not be used. The right plug has the termination OFF.
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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DB9 connector DB9 connector –– ExampleExample of the termination switchof the termination switch
Termination only at the end (normal situation)
RS 485 and PROFIBUS DP
Master SlaveSlave Slave Slave Slave Slave
Termination also in the middle
2. Branch is disconnected!
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55
1. Termination somewhere on the cable.
2.0
Plug with termination OFF.
Plug with termination ON.
Master SlaveSlave Slave Slave Slave Slave
DB9 connector DB9 connector –– Fast ConnectFast Connect
Only use cables with solid core wires.
Cables must be suitable for Fast Connect (wire and cable thickness)
RS 485 and PROFIBUS DP
cable thickness).
It is recommended NOT to use the plug for the 2nd time.
If a new plug is assembled on an already used cable, then prepare the cable again (new clean wires).
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PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Checklist 9Checklist 9--pin plug selectionpin plug selection
Angle of the plug?
Maximum baudrate?
Piggy back connector?
RS 485 and PROFIBUS DP
ggy
Can the termination be switched ON/OFF?
When termination is switched ON, is the outgoing channel disconnected?
Which one is the outgoing channel?
If Fast Connect, is the cable suitable?
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Grounding and shielding system?
IP class?
Is the plug reusable?
Value of the series resistance?
2.0
M12 connectorM12 connector -- StructureStructure
With IP65 applications, the M12 system is often used.
RS 485 and PROFIBUS DP
Tee for chaining
Terminator
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Tee for chaining
1.1
Instrument with2 connectors
(male and female)
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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M12 connector M12 connector –– Pin layoutPin layout
The pin layout of the M12 connector has been defined as follows:
RS 485 and PROFIBUS DP
12
34
5
Ref. point
Pin no. Signal Function
1 VP +5V supply for termination
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2.0
2 RxD/TxD-N Data line minus (A-line)
3 DGND Data ground
4 RxD/TxD-P Data line plus (B-line)
5 Shield Ground <NOT USED ANYMORE>
Thread Shield Ground
M12 requires accurate assemblyM12 requires accurate assembly
RS 485 and PROFIBUS DP
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Twisted and broken wires during assembly of the M12 connector.
1.0
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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FerrulesFerrules
Ferrules are NOT mandatory.
Choose ferrules that are suited for data communication.
RS 485 and PROFIBUS DP
OK
For example: galvanised copper. Do NOT use aluminium!
Make sure you use the correct ferrule size.
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Not OK
Make sure the wires are pressed in deep enough.
Use correct tools.
1.0
The bus is terminated on both ends with terminating resistors.
5 Volt
TerminaTerminattionion -- StructureStructure
RS 485 and PROFIBUS DP
B
A
390 Ohm
220 Ohm
The termination consists out of 3 resistors.
The power supply takes care of a valid logic level when non of the devices are active on the bus.
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A
GND
390 Ohm Without the power supply the
terminating resistor is not equal to the cable impedance!
1.2
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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First station Last station
Termination Termination -- ApplicationApplication
VP (6) VP (6)
RS 485 and PROFIBUS DP
B (3)
A (8)
DG (5)
390
220
390
B (3)
A (8)
DG (5)
B line
A line
390
220
390
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63
B BA A
Station 2 Station 3
1.1
Termination must always be present and powered at all times.….If the user wants more guarantee, then an active termination is the best solution.Termination must always be present and powered at all times.….If the user wants more guarantee, then an active termination is the best solution.
Oractive termination
Oractive termination
He was correct! The termination is switched ON.He was correct! The termination is switched ON.
RS 485 and PROFIBUS DP
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1.0
Sometimes the laptop was connected at this place!But, there is NO powered terminated here.Sometimes the laptop was connected at this place!But, there is NO powered terminated here.
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Active TerminationActive Termination
Master
RS 485 and PROFIBUS DP
Power
“Last”Sl
Slave Slave Slave
Power
Power
Slave“Last” Slave
Slave Slave
Power
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4.0
Slave Slave Slave Slave
In this segment every station can be removed or powered down without disrupting the network.
TerminationTermination -- ExampleExample
The use of active termination for higherreliability and simplification of
maintenance activities.
The use of active termination for higherreliability and simplification of
maintenance activities.
RS 485 and PROFIBUS DP
- 5 segments end in this cabinet. - 5 segments end in this cabinet.
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1.0
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Termination Termination –– Coupling componentsCoupling components
RS 485 and PROFIBUS DP
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Termination is often forgotten when coupling components are involved.
Termination is often forgotten when coupling components are involved.
1.0
VP (6)
First station Second station
VP (6)
Termination Termination –– Only 2 devicesOnly 2 devices
RS 485 and PROFIBUS DP
At least 2 meters cable
VP (6)
B (3)
A (8)
DG (5)
390
220
390
VP (6)
B (3)
A (8)
DG (5)
B line
A line
390
220
390
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1.0
When a segment only has 2 devices, it is recommended to install a cable length of at least 2 meters!When a segment only has 2 devices, it is recommended to install a cable length of at least 2 meters!
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Repeaters are network components to enlarge the cable length and to increase the number of stations (more than 32).
RepeatersRepeaters
RS 485 and PROFIBUS DP
TTMax. 1200 m
Max. 31 stations
Max. 31 stations
Max. 29 stations
Max. 31 stations
TT
TT
TT
TT
Max. 1200 m
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69
3.0
Repeaters are also bus loads and terminatingresistors need to be placed again.
Repeaters are also bus loads and terminatingresistors need to be placed again.
TTTT
TTMax. 1200 mMax. 1200 m
TT
Questions about repeaters ???Questions about repeaters ???
RS 485 and PROFIBUS DP
Max. 31 stations Max. 29 stations
T
T
T
Max. 1200m
What is the highest baudrate that is allowed in this installation?
Max. 31 stations Max. 31 stationsT
TT
T
Max. 1200m
Max. 1200mMax. 1200m
T
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70
g
Why does the top-right segment have 29 stations?
Where in this installation can we hook up a laptop with a PROFIBUS card?
What is special about the termination on the top-left and bottom-right?
What happens when a segment has a short circuit?
2.0
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Repeaters Repeaters -- StructureStructure
Segment 1 Segment 1
RS 485 and PROFIBUS DP
Isolation
Segment 11. The shielding can still be 1 on 1.
2. A tap point can be isolated or directly connected with a
3. Termination can be activated when the bus ends/starts at the repeater.
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Segment 2Segment 2
segment.p
2.0
Wrong wiring of repeatersWrong wiring of repeaters
RS 485 and PROFIBUS DP
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Now they have 41 devices on the same segment!Now they have 41 devices on the same segment!
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Example Example –– Repeater backboneRepeater backbone
A DP backbone on which 4 repeaters are connected. At the other side of the
t t t t
A DP backbone on which 4 repeaters are connected. At the other side of the
t t t t
RS 485 and PROFIBUS DP
repeaters a new segments starts.repeaters a new segments starts.
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73
The terminators are only activated at the ‘left side’.The terminators are only activated at the ‘left side’.
Beware of the ‘1 meter rule’!Beware of the ‘1 meter rule’!
2.0
ProfiHubs are more efficient for repeater backbonesProfiHubs are more efficient for repeater backbones
Long spur lines to instruments and the possibility to remove/insert them during operation. Short circuit protection on each spur line is automatically provided.
RS 485 and PROFIBUS DP
DP backbone
Each spur line
Wiring problemsdo not spread to
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Each spur line can be 200 m at 1,5 Mbps.
do not spread to other spur lines.
1.0
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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For testing it is recommended to set the baudrate to the lowest possible speed (9,6 kbps). Most networks operate ‘correctly’ on this speed even when they have installation, cabling and termination faults. You can now check your
ti d dd i
TestingTesting
RS 485 and PROFIBUS DP
connections and addressing.
Low Baudrate
High Baudrate
Low % of Overall Bit Transmission Time
High % of Overall Bit Transmission Time
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2.0
High % of Overall Bit Transmission Time
At higher baudrates there is more chance of bus faults!
This page has been intentionally left blank.
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PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Aarding en afscherming
Grounding and shielding
Grounding and shieldingGrounding and shielding
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1.1
External influences on data communicationExternal influences on data communication
Grounding and shielding
Sender Receiver
EMI
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Currents
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Interference by external sourcesInterference by external sources
High Voltage
Electrostatic injection:Capacitive coupling caused by nearby power lines.
Grounding and shielding
g g
Interference sourcee.g. Power cable Capacitive coupling between cables
Pickup
Electromagnetic injection:Magnetic fields caused by high currents in nearby cables.
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High Current
Inductive coupling between cables
Pickup
Interference sourcee.g. Power cable
Magnetic fields caused by high currents in nearby cables.
Reduction of electromagnetic injectionReduction of electromagnetic injection
The twist in the wires eliminates magnetic fields.
Try to keep the twist in the wires when the sheath has been removed.
Grounding and shielding
Pickup
This theory is valid for al signal cariers!
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Induced currents in adjacent loops tends to cancel
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Reduction of electrostatic injectionReduction of electrostatic injection
The shielding of the cable reduces electrostatic injection!
Ground on multiple points (resistance reduction).
Grounding and shielding
High VoltageInterference sourcee g Power cable k d
As thick possible.
Non grounded shielding has no effect!
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e.g. Power cable
Pickup
Pickup passes to groundRs Rs Rs
Rs = Shield resistance
What does IEC61000What does IEC61000--55--2 say about grounding?2 say about grounding?
Ground as many points as possible. This reduces the resistance (less noise).
Grounding and shielding
Be careful of the amount of current flowing through the shield. When the current gets too high, use;- fiber optic- extra ground cable- repeaters with isolation
Avoid the use of ‘pigtails’
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Avoid the use of ‘pigtails’.
Avoid connection with the ‘minus’ of power supplies.
3.1
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Grounding and shielding between cabinetsGrounding and shielding between cabinets
Slave Slave
Master
Grounding and shielding
ground rail ground rail ground rail
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PROFIBUS cable
Ground cable
PROFIBUS cable
1.0
Additional grounding pointsAdditional grounding points
Grounding and shielding
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2.0
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ExampleExample -- ShieldingShielding notnot connectedconnected
Grounding and shielding
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1.0
Policy of separationPolicy of separation
Grounding and shielding
As far away as possible!
Power line
As close as possible!Ground potential
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2.0
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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The voltage levels and applications of cable needs to be classified into categories.
Category I:Fieldbus and LAN cables (PROFIBUS, PROFINET, ASi, etc.).Shi ld d bl f di it l d t ( i t RS 232 t )
Air gaps (1)Air gaps (1)
Grounding and shielding
Shielded cables for digital data (printer, RS 232, etc.).Shielded cables for analog and digital signals (25 V).Low voltage cables (60 V).Coax cables
Category II:Cable with DC voltage >60 V and 400 V.Cable with AC voltage >25 V and 400 V.
Category III:
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Category III:Cables with DC and AC voltage >400 V.Telephone cables.
Category IV:All cables from group I to III with the direct danger of lightning strikes (connections between
buildings or open air applications).
2.0
Air gaps (2)Air gaps (2)
20 cm
When cables are placed side by side, they have to comply to the following air gaps:
Grounding and shielding
Cablecategory
I
Cablecategory
II
Cablecategory
III
Cable
10 cm 10 cm
50 cm
50 cm 50 cm
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categoryIV
50 cm 50 cm
The air gaps are based on air space. In case of grounded metal plates, the distances can be reduced.
Cables of different categories may cross each other.
2.0
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Air gaps (3)Air gaps (3)A measurement of a packing machine in which the PROFIBUS cables are placed too close to power lines.
Grounding and shielding
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89
Power lines are removed.
Power lines are too close.
3.0
Example Example -- Air gapsAir gaps
Power cablesExample: 230 V
Compressed air cables
Data communication cablesExample: PROFIBUS
Grounding and shielding
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The data communication cables have been placed more than 10 cm distance from the 230 V cables.The data communication cables have been placed more than 10 cm distance from the 230 V cables.
2.0
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Separation of cables in metal cable traysSeparation of cables in metal cable trays
B di
Grounding and shielding
Cat I Cat II Cat III
Channel lid Bonding
Bonding
Channel
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Bonding
Channel
1.0
Creating a more reliable installationCreating a more reliable installation
Repeater backbones with repeaters/ProfiHubs (isolation of problems)
External powered termination (removing/adding devices)
Summary
Reduce the baudrate (improves signal quality)
Increase the repeats/retries (increases success rate)
Reduce the spur/stub lines or use repeaters/ProfiHubs (improves signal quality)
Cable as close as possible to ground (decr. EMC sensitivity)
Additional grounding points (decr. EMC sensitivity)
Activate the watchdog on all devices (safety)
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Activate the watchdog on all devices (safety)
Use fiber optic for long distances (isolation of problems)
It is assumed that the installation complies with the PROFIBUS rules!It is assumed that the installation complies with the PROFIBUS rules!
1.0
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Making troubleshooting easyMaking troubleshooting easy
Measurement connectors on every segment (start of the cable)
Every segment has its own addressing range (10..19, 20..29, etc)
Summary
Individual repeaters/OLMs can be powered up/down
Individual devices can be powered up/down
PLC/DCS at the beginning of the cable
Diagnostics is enabled in the devices
Installation drawing in 1 or 2 pages (with cable lengths and addresses)
Addresses clearly marked on the devices
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Addresses clearly marked on the devices
All GSD files are available in ProfiTrace
Access to the PLC/DCS configuration
1.0
This page has been intentionally left blank.
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B i i i l fB i i i l fBasic principles of Basic principles of transmission technologytransmission technology
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1.0
Cable properties (4..20 mA)Cable properties (4..20 mA)
R/2 R/2
G
R /k ( l l )
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R = /km (real value)G = S/km (real value)
In DC situations every cable complies to this specification. Losses and cable resistance can easily be determined.
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Cable properties (PROFIBUS)Cable properties (PROFIBUS)
R/2 L/2 R/2L/2
R = /km
GCG = S/kmL = H/kmC = F/km
I d AC i t Zj L R
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Impedance = AC resistance Zj C G
In DC and AC situations every cable complies to this specification. Losses are calculated with another formula.
LossesLosses
R L
R l G l Z R l
U2U1 GC
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Example: Z = 100 l = 1000 m R = 0,1 /m -> losses = 40%
U U eR l
Z
G l Z
2 1 2 2
U U eR l
Z2 1 2 if G = 0 S
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Skin effect (1)Skin effect (1)
The losses are also linked to the skin effect. When the frequencies increase, the electrons move to the outer layer of the cable. This causes an increase in the cable resistancecable resistance.
F (MHz) (um)
1
100
10.000
68
6.8
0.68
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This becomes important at frequencies above 100 kHz. De resistance increases with . f
The frequency is the factor which determines the maximum cable length
Hz
Maximum cable lengthMaximum cable length
dB
Hz
U1 U2cable Rt
With PROFIBUS:
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Transmissionspeed in kbit/s
9.6 19.2 45.45 93.75 187.5 500 1500 3000 6000 12000
Segment lengthin m
1200 1200 1200 1200 1000 400 200 100 100 100
With PROFIBUS:
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Propagation delaysPropagation delays
Because of the inductance and capacitance, the cable is subject to propagation time. On typical twisted-pair cables this is:
With most PROFIBUS cables this is:
4.2 ns per meter or 420 ns per 100 m or
0.84 us per 200 m or
4.2 us per km
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This is about 200.000 km/s -> 60% of the speed of light.
ReflectionsReflections
A physical characteristic of objects which have ‘speed’ is that they reflect whenever they are blocked in their path.
This characteristic can also be found in transmission lines. Solutions for the termination of reflections is the use of terminating resistors.
RtRt
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Rt = ZoRt = Zo
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Rt=Zo
Zo=150 ,L=100m
Correct terminated cableCorrect terminated cable
The signal amplitude has been The signal amplitude has been
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103
The signal amplitude has been attenuated (dep. On the cable length and baudrate).
The propagation indicates 100m cable length (420 ns).
The signal amplitude has been attenuated (dep. On the cable length and baudrate).
The propagation indicates 100m cable length (420 ns).
Acceptable signalAcceptable signal
1 V idle level because of powered terminationtermination
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Acceptable reflections
No noise during idle state
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Zo=150 ,L=100m
Cable without terminationCable without termination
Start
t2
t1
t4
t3
t6
t5
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Start End
Endt7
The “width” of a reflection indicates the distance! Example: 840 ns = 100 m (to the end and back).The “width” of a reflection indicates the distance! Example: 840 ns = 100 m (to the end and back).
Termination missing or wire break (nearby)Termination missing or wire break (nearby)Detected glitch in the signalling
Detected glitch in the signalling
The reflections are compressed in the bit because the cable is short or the
The reflections are compressed in the bit because the cable is short or the
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g gdisturbance is nearby. But, some reflections have a high amplitude that affects the bit interpretation.
disturbance is nearby. But, some reflections have a high amplitude that affects the bit interpretation.
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Test- and measurement tools
TestTest-- and measurement toolsand measurement tools
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2.0
Fault topFault top--55
1) Termination.
Test- and measurement tools
2) Power lines.
3) Cabling rules.
4) Configuration faults.
5) Damaged or not-certified interfaces.
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Statistics from 300 field trips worldwide.
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Handheld toolsHandheld tools
• Siemens BT200
• ComSoft Nettest II
Functions:Wire breaks/short circuits
Test- and measurement tools
ComSoft Nettest II Voltage or shielding faults Localizing faults Measuring cable lengths Termination detection List of slaves Logging
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109
Non active segments (masters have been removed)!
2.2
Test and evaluation Test and evaluation mastersmasters
PROFIBUS MasterBihl & Wiedeman
Test- and measurement tools
ProfiCaptainPROCENTEC
F ti
Maximum baudrate 19,2kand RS 232!
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110
Functions: Configuration I/O Testing Diagnostics Live List and Network Scan Set Slave Address
4.0
USB
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OscilloscopesOscilloscopes
Test- and measurement tools
Functions Amplitude Reflections
1st: Large + Difficult
2nd: Expensive
3rd: Difficult 4th: Small, Fast and Easy
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111
Noise EMC
The oscilloscope is the only tool that can display the bus signals!The oscilloscope is the only tool that can display the bus signals!
6.0
BusmonitorsBusmonitors / Analyzers/ Analyzers
• ProfiTrace 2 - PROCENTEC
• Bus check - Softing
Test- and measurement tools
• PBScope - T+H
• IT-Monitor - ITM / ComSoft / TMG-itec
• Amprolyzer
Functions
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112
Active network!
6.0
Functions Live List Messages Device diagnosis Cycle times Logging
USB
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Tap ConnectorTap Connector
Oscilloscope
Test- and measurement tools
| | | | | | | | | | | | | | | | | | | |
0 cm 10 cm 20 cm
ProfiCore
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2.0
Example Example –– No measurement connectorsNo measurement connectors
Test- and measurement tools
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2.0
It is highly recommended to put a measurement connector on the PLC/DCS when the cable also starts here.It is highly recommended to put a measurement connector on the PLC/DCS when the cable also starts here.
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Required tools to exactly pinpoint “the fault”Required tools to exactly pinpoint “the fault”
Faults on DP Passive cable Running installation
General communication faults Not possible ProfiTrace
Double address Not possible ProfiTrace
Test- and measurement tools
Double address Not possible ProfiTrace
Wrong address BT200 ProfiTrace
No termination BT200, Multi meter Oscilloscope
Too many termination BT200, Multi meter Oscilloscope
Missing device (power off, connector removed, etc)
BT200 ProfiTrace, Configuration tool
Device diagnostics Not possible ProfiTrace, Configuration tool
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115
Shortcircuit, break, crossed wires, etc BT200, Multi meter Oscilloscope
EMC problems Oscilloscope Oscilloscope
1 Meter rule Not possible Oscilloscope
Configuration faults Not possible ProfiTrace
1.0
Facts and FictionFacts and FictionFacts and FictionFacts and FictionTh i l fTh i l fTh i l fTh i l fThe most important tools for The most important tools for troubleshooting a network troubleshooting a network
during operation are an during operation are an illill dd
The most important tools for The most important tools for troubleshooting a network troubleshooting a network
during operation are an during operation are an illill dd
Copyright © 1999-2011 PROCENTEC. All rights reserved. www.procentec.com
oscilloscopeoscilloscope and a and a busmonitor/analyzerbusmonitor/analyzer..oscilloscopeoscilloscope and a and a
busmonitor/analyzerbusmonitor/analyzer..
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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Facts and FictionFacts and FictionFacts and FictionFacts and FictionA multiA multi--meter is not useable meter is not useable
for dynamic signal for dynamic signal measurement!measurement!
A multiA multi--meter is not useable meter is not useable for dynamic signal for dynamic signal
measurement!measurement!
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Busparameters
BusparametersBusparameters
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3.0
Introduction BusparametersIntroduction Busparameters
Busparameters are settings that define the timing behavior on the bus.
By means of a config tool the busparameters are set at every master.
The most part of the busparameters have to be the same on all masters.
Busparameters
p p
“Modern” config tools set the busparameters automatically.
What is the reason to set busparameters:
Extension to other media (DP to PA).
Use of many fibre optic couplers or repeaters (delay times).
Performance improvement (efficiency).
T k d di t b (k i th i t ll ti i )
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1.2
To work around disturbances (keeping the installation running).
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Standard BusparametersStandard Busparameters
Busparameters have to be set at every master (automatically or by the user):
Baudrate Transmission speed (Baudrate) (10 possibilities)
TS Master address (0 to 126)
Busparameters
TSET
TQUI
max TSDR
min TSDR
Setup Time
Quiet Time
Largest Station Delay Responder
Smallest Station Delay Responder
20 to 28-1 (bit times)
0 to 28-1 (bit times)
20 to 216-1 (bit times)
20 to 216-1 (bit times)
Baudrate Transmission speed (Baudrate) (10 possibilities)
TSL Slot Time 52 216-1 (bit times)
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3.0
Max Retry Limit
HSA
TTR
Maximum Retries
Highest Station Address
Target Rotation Time
0 to 8
2 to 126
20 to 224-1 (bit times)
G GAP Update Factor 1 to 100
The Slot Time is the maximum time the master waits for the complete reception of the first byte of a response (11 bits).
TTSLSL (Slot Time)(Slot Time)
Busparameters
Within the Slot Time the first byte should be received, otherwise the master will attempt a retry (repeat), or continue with other actions.
23n 1
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1 2 n
2.1
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This is the maximum time the slave could need to send the first bit of a response back.
With PROFIBUS DP thi l i t d di d
maxTmaxTSDRSDR (Largest Station Delay Responder)(Largest Station Delay Responder)
Busparameters
With PROFIBUS DP this value is standardized.
minTSDR < Response < maxTSDR
maxTSDR < TSL
23n 1
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123
1 2 n
2.0
This is a time the slave has to wait before it can send a response back.
With PROFIBUS DP this time is sent with the parameters to the slaves. This is
min Tmin TSDRSDR (Smallest Station Delay Responder)(Smallest Station Delay Responder)
Busparameters
pthe reason why this parameter is set in the master.
Standard value: 11 bit times (to calm the bus).
minTSDR < Response
23n 1
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23n 1
1 2 n
2.0
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The Quiet Time controls the time when the bus electronics or software of the sender are set to ‘receive mode’ after a message has been sent.
TTQUIQUI (Quiet Time)(Quiet Time)
Busparameters
This parameter has to be set when reflections or other negative elements are involved.
TQUI < minTSDR
Standard value: 0 bit times
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2.0
The Setup Time is an extra waiting time which is started before a message is sent (offset).
TTSETSET (Setup Time)(Setup Time)
Busparameters
The Setup Time is often used when DP/PA couplers or other media ‘transitions’ are involved. It should be set to the device which needs the longest Setup Time (stated in the manual).
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Busparameter timing diagramBusparameter timing diagram
Busparameters
Tid1Master Slave
Tim
e
Response
minTSDR (11..x Tbit)
TSDR (60 800 Tbit)
Request
Request
Tslot
Tqui
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2.2
maxTSDR (60..800 Tbit)Response
Tid1
Tid1 = 33 Tbit + 2*Tset + internal master delayTid1 = 33 Tbit + 2*Tset + internal master delay
New transaction starts here…
G (GAP Update Factor)G (GAP Update Factor)
With this parameter the factor is set after how many token cycles the master will search for a new master (FDL_Status message – SD1).
Busparameters
TGUD = G * TTR
If the factor is high, the network will increase in bus cycle efficiency, but it will be slower for master insertions.
Standard value: 10
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A couple of masters ignore this parameter and always operate according to G = 1.
2.1
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HSA (Highest Station Address)HSA (Highest Station Address)
This parameter sets the highest address in the network. Above HSA the master does not ‘look’ anymore.
Busparameters
A decrease of HSA makes the insertion of new masters quicker. The overall network performance is not effected.
Masters which have a higher address number than the HSA value, will not be able to access the network.
Standard value: 126
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1.0
Max Retry Limit (Maximum Retries)Max Retry Limit (Maximum Retries)
This parameter sets the number of retries which are taken when a receiver does not respond to a message (not for FDL_Status messages).
Busparameters
Max Retry Limit is increased by the user when the network is exposed to distortions. The overall cycle time will be damaged because the message is repeated.
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Standard busparameters for PROFIBUS DPStandard busparameters for PROFIBUS DP
Busparameters
Busparameterversus Baudrate
9.6 k 19.2 k 45.45 k 93.75 k 187.5 k 500 k 1.5 M 3 M 6 M 12 M
TSL [bit times] 100 100 640 100 100 200 300 400 600 1000
Max_Tsdr [bit times] 60 60 400 60 60 100 150 250 450 800
Min_Tsdr [bit times] 11 11 11 11 11 11 11 11 11 11
TSET [bit times] 1 1 95 1 1 1 1 4 8 16
TQUI [bit times] 0 0 0 0 0 0 0 3 6 9
G f t 1 1 10 1 1 1 10 10 10 10
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1.2
Gap factor 1 1 10 1 1 1 10 10 10 10
HSA 126 126 126 126 126 126 126 126 126 126
Max_Retry_Limit 1 1 1 1 1 1 1 2 3 4
WatchdogWatchdog
The watchdog is a supervision time which is set/calculated in the configuration tool of the master. The watchdog will be transferred to all configured slaves.
Busparameters
Within the watchdog time, the master has to “contact” the slave. If this is not the case, the slave leaves the Data Exchange state.
When the watchdog is calculated by the configuration tool, the value is in most cases 6x the “worst case” cycle time.
Range: 10 ms .. 650 s.
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2.0
Cycle time << Watchdog (ideal is 6x)
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Single Master Single Master -- 1 master with 24 slaves1 master with 24 slaves
Busparameters
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1.1
Watchdog
Cycle time
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PROFIBUS PA
MBP and PROFIBUS PAMBP and PROFIBUS PA
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3.0
RS 485RS 485 Baudrates from 9,6 kbit/s to 12 Mbit/s
Shielded twisted pair cable
32 devices per segment
PROFIBUS PA
Distance: 12 Mbit/s = 100 m; 1,5 Mbit/s = 200 m; < 187,5 kbit/s = 1.000 m
Distance extendable with repeaters
MBPMBP--ISIS Fixed baudrate of 31,25 kbit/s
Intrinsic safety (option) and power over the bus
Shielded twisted pair cable
Distance up to 1.900 m per segment dep. on Ex-class and power consumption
10 32 devices per segment dep on Ex class and power consumption
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136
10-32 devices per segment, dep. on Ex-class and power consumption
Fiber opticsFiber optics Baudrates from 9,6 kbit/s up to 12 Mbit/s
Monomode, Multimode, plastic or PCS/HCS fibers are available
Distance extendable with repeaters up to 100 km
2.0
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PROFIBUS PAPROFIBUS DP
DP/PA segment couplerDP/PA segment coupler
PROFIBUS PA
MBP-ISRS 485
AsynchronousNRZ coding
1 character = 11 bits(8 user bits + 1 start + 1 stop + 1 parity)
Variable baudrates
Synchronous Manchester coding
1 character = 8 bits
Fixed baudrate = 31 25 kbps
DP/PA coupler
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137
Variable baudrates Fixed baudrate = 31,25 kbps
2.2
PROFIBUS PA
=PROFIBUS DP/DP-V1
The principle of PROFIBUS PAThe principle of PROFIBUS PA
PROFIBUS PA
x+PROFIBUS DP
PROFIBUS DP/DP-V1
+Intrinsic safe communication properties
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138
PROFIBUS PA
J
1.0
PROFIBUS Troubleshooting & Maintenance V8.1.0 14 January 2011
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MBP SignalingMBP Signaling
The instrument power supply (2-wire) is generated by the DP/PA coupler. It is normally between 12 to 24 V with a current of 90 to 400 mA, dependant
The instrument power supply (2-wire) is generated by the DP/PA coupler. It is normally between 12 to 24 V with a current of 90 to 400 mA, dependant
PROFIBUS PA
current of 90 to 400 mA, dependant on the Ex zone.current of 90 to 400 mA, dependant on the Ex zone.
Fig. 1 DC measurement
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139
The data (31,25 kbit/s) is modulated on the power supply with an amplitude of 750 mV to 1 V (peak-to-peak).
The data (31,25 kbit/s) is modulated on the power supply with an amplitude of 750 mV to 1 V (peak-to-peak).
2.3
Fig. 2 AC measurement
MBP MBP SignalingSignaling
Transm it level characteristics Lim its
O utput leve l (peak-to-peak) 0.75 V to 1 V
PROFIBUS PA
M axim um positive and negative am plitude d ifference (s ignaling b ias)
± 50 m V
M axim um output level; open c ircuit (peak-to-peak)
35 V
R eceive c ircu it characteris tics Lim its
Input im pedance, m easured over the freq uency range 0.25 fr to 1.25 fr
3 kΩ
Sensitiv ity; m in . peak-to-peak s ig na l req u ired to be accepted
150 m V
N oise re jection ; m ax peak-to-peak
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140
N oise re jection ; m ax. peak to peak no ise requ ired to be re jec ted
75 m V
1.0
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PROFIBUS PA
DP/PA couplersDP/PA couplersand linksand links
DP/PA couplersDP/PA couplersand linksand links
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1.0
11
Siemens segment coupler Siemens segment coupler -- AddressingAddressing
PROFIBUS PA
PROFIBUS DP
PROFIBUS PA
55 4433
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1.1
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DP/PA segment coupler from SiemensDP/PA segment coupler from Siemens
StandardPA current: 400 mA
PROFIBUS PA
[EEx ia] II C
[EEx ib] II CPA current: 110 mAPA voltage: 12,5 V
PA voltage: 19 V
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143
[EEx ia] II CPA current: 90 mAPA voltage: 12,5 V
DP baudrate: 45,45 kbpsDP connector: DB9DP termination: NoPA connector: ScrewPA termination: Switchable
(Non-Ex only)
DP baudrate: 45,45 kbpsDP connector: DB9DP termination: NoPA connector: ScrewPA termination: Switchable
(Non-Ex only)
2.3
StandardPA current: 400 mA
DP/PA segment couplers from PDP/PA segment couplers from P++FF
PROFIBUS PA
[EEx ia] II CPA current: 100 mAPA voltage: 13 V
PA voltage: 25 V
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DP baudrate: 93,75 kbpsDP connector: ScrewsDP termination: Yes
PA connector: ScrewsPA termination: Integrated
DP baudrate: 93,75 kbpsDP connector: ScrewsDP termination: Yes
PA connector: ScrewsPA termination: Integrated
3.1
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PROFIBUS PA
DP/PA linkDP/PA linkssDP/PA linkDP/PA linkss
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145
PROFIBUS DP
DP/PA link from SiemensDP/PA link from Siemens
PROFIBUS PA
9,6 kbit/s to12 Mbit/s
PROFIBUS PA
Link Coupler
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DPSLAVE
DPMASTER 45,45 kbit/s
31,25 kbit/s
2.0
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slave 105 Q bytes
DP/PA link from SiemensDP/PA link from Siemens
PROFIBUS PA
DPMASTER
slave 155 I bytes
slave 125 I bytes
DPSLAVE
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147
slave 10slave 15slave 12
I
O5 bytes 5 bytes
5 bytes
I
O10 bytes
5 bytes
Max. 5 standard Siemens DP/PA
DP/PA link from SiemensDP/PA link from Siemens
PROFIBUS PA
couplers (Ex and Non-Ex)
Standard Siemenssegment coupler Ex and Non-Ex
Standard Siemenssegment coupler Ex and Non-Ex
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DP baudrate: 9,6 kbps to 12 MbpsGateway is DP slave: YesNumber of bytes: 244 bytes Input/Output for the complete PA networkField instruments: Max. 31 slaves in Data Exchange
DP baudrate: 9,6 kbps to 12 MbpsGateway is DP slave: YesNumber of bytes: 244 bytes Input/Output for the complete PA networkField instruments: Max. 31 slaves in Data Exchange
Gateway, DP slave, PA masterGateway, DP slave, PA master
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1 ms
Cycle time with a DP/PA link from SiemensCycle time with a DP/PA link from Siemens
PROFIBUS PA
DP/PA link
up to 12 Mbit/sPROFIBUS DP
PROFIBUS PA
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15,5 ms15,5 ms
15,5 ms
11
Addressing with a DP/PA link from SiemensAddressing with a DP/PA link from Siemens
PROFIBUS PA
PROFIBUS PALink
PROFIBUS DP
PROFIBUS PALink44 33
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150
33 44 55 44 5533
The lowest address behind the link is 3.The lowest address behind the link is 3.
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Siemens DP/PA link Siemens DP/PA link –– Measuring the 45,45 kbps sideMeasuring the 45,45 kbps side
Connect the A line to pin 8 on DB 9
PROFIBUS PA
Connect the A-line to pin 8 on DB-9Connect the B-line to pin 3 on DB-9
DB-9 (Female)
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151
On the backplane, the 45,45 kbps side is available on the bottom 2 pins. When a DB9 connecter is attached it can directly be connected with an analyzer (RS 485).On the backplane, the 45,45 kbps side is available on the bottom 2 pins. When a DB9 connecter is attached it can directly be connected with an analyzer (RS 485).
2.2
A
B
PROFIBUS PA
DP/PA linkDP/PA linkfromfrom Pepperl+FuchsPepperl+Fuchs
DP/PA linkDP/PA linkfromfrom Pepperl+FuchsPepperl+Fuchs
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DP/PA link from PDP/PA link from P++F F -- SpecificationsSpecifications
StandardPA current: 400 mAPA voltage: 24 V
PROFIBUS PA
[EEx ia] II CPA current: 100 mAPA voltage: 12,8 V
g
Power-Link Non-Ex(segment coupler)
Power-Link Non-Ex(segment coupler)
Transparantgateway
(redundant
Transparantgateway
(redundantPower-Link Ex
(segment coupler)Power-Link Ex
(segment coupler)
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153
DP baudrate: 9,6 kbps to 12 MbpsGateway is DP slave: NoNumber of bytes: 244 bytes Input and 244 bytes Output per PA slaveField instruments: 124 slaves in Data Exchange
DP baudrate: 9,6 kbps to 12 MbpsGateway is DP slave: NoNumber of bytes: 244 bytes Input and 244 bytes Output per PA slaveField instruments: 124 slaves in Data Exchange
(segment coupler)(segment coupler)(redundantoption)
(redundantoption)
(segment coupler)(segment coupler)
3.1
11
DP/PA link from P+F DP/PA link from P+F -- AddressingAddressing
PROFIBUS PA
PROFIBUS DP
PROFIBUS PA
55 4433
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154
Because of the semi-transparency, address 1 for DP and PA slaves is not allowed.Because of the semi-transparency, address 1 for DP and PA slaves is not allowed.
1.1
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Star- and bus constructions can be realized.
Topology of MBPTopology of MBP--ISIS
PROFIBUS PA
PROFIBUS DP
DCS/PLC
DP/PA-Link
x+
Junction Box
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24 VPROFIBUS PA “T“
Segment
Explosion zone restrictionsExplosion zone restrictions
Area Zone 0 Eex ia IIC
Zone 1 Eex ib IIB
Zone 2 Non EX
Voltage 13,5 V 13,5 V 24 V
PROFIBUS PA
g , ,
Maximum power 1,8 W 4,2 W 12 W
Maximum current draw 110 mA 250 mA 500 mA
Maximum segment length 1.000 m 1.900 m 1.900 m
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Spur length per device (1 to 10 stations)
30 m 30 m 120 m
Number of stations 10 20 32
These are the maximum allowable values! DP/PA couplers could have specifications of ‘less’ quality.These are the maximum allowable values! DP/PA couplers could have specifications of ‘less’ quality.
2.0
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25 32
Length of the spur(Ex)
Length of the spur(not Ex)
M i 1
Spurs/Stubs with MBPSpurs/Stubs with MBP--ISIS
M i 1
Number of Spurs
PROFIBUS PA
25 to 32
19 to 24
15 to 18
13 to 14
Maximum 1 m
30 m
60 m
90 m
Maximum 1 m
30 m
30 m
30 m
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1 to 12 120 m30 m
Maximum 3 instruments on a spur. Spurs under 1 meter do not have to be calculated. Maximum 3 instruments on a spur. Spurs under 1 meter do not have to be calculated.
1.0
Cable design
Type A(Reference)
Twisted pair,
Type B Type DType C
Multiple twisted pairs total
Multiple twisted pairs not
Multiple non-twisted pairs
Cable specifications of MBPCable specifications of MBP--ISIS
PROFIBUS PA
Cable design
Maximum conductorcross section (nominal)
Loop resistance(direct current)
Impedance (31,25 kHz)
Attenuation (39 kHz)
shielded
0,8 mm²(AWG 18)
44 Ohm/km
100 Ohm +20%
3 dB/km
pairs, total shielded
pairs, not shielded
twisted pairs, not shielded
0,32 mm²(AWG 22)
0,13 mm²(AWG 26)
1,25 mm²(AWG 16)
112 Ohm/km 264 Ohm/km 40 Ohm/km
100 Ohm +30% ** **
5 dB/km 8 dB/km 8 dB/km
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Capacitive asymmetry
Max. Propagation delaychange (7,9 to 39 kHz)
Max. shield coverage
Cable length
2 nF/km
1.7 usec/km
90%
1.900 m
2 nF/km ** **
** ** **
** - -
1.200 m 400 m 200 m
** Not specified
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R =100 Ohm
Termination in a PA bus structureTermination in a PA bus structure
PROFIBUS PA
T
C =1 F
PROFIBUS PA
PROFIBUS DP
R =100 Ohm
C =1 F
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1.0
Termination in a PA “ChickenTermination in a PA “Chicken--Foot” topologyFoot” topology
R =100 Ohm
PROFIBUS PA
300m
10m 30m 20m
JunctionBox
C =1 F
R =100 Ohm
C =1 F
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MBP termination MBP termination –– Missing terminationMissing termination
PROFIBUS PA
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When termination is missing, the peak-to-peak voltage will be 1,5 V or higher.When termination is missing, the peak-to-peak voltage will be 1,5 V or higher.
1.1
Interconnection technology for IP 65 or higher (PA)Interconnection technology for IP 65 or higher (PA)
PROFIBUS PA
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M12 connectorM12 connector
PROFIBUS PA
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Instrument side Junction box/ T-box side
1.0
Strategy of troubleshootingStrategy of troubleshooting
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Classifications of most common PROFIBUS problemsClassifications of most common PROFIBUS problems
Physical level
Device is NOT communicating anymore
Periodically no communication with a device
Application level
Invalid data (calibration or bug)
Device diagnostics (I/O problems)
The worst one
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What kind of fault finding methods are at hand?What kind of fault finding methods are at hand?
1) Analyzer most important!
2) Electrical measurement
3) Visual inspection
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The sequence above is also the way of working for localizing and solving ‘problems’.
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Indicators (LEDs)Indicators (LEDs)
Most devices have indicators, which clarify the status of the device. This is very important for the users, especially maintenance personnel. With 3 indicators a lot of situations can be cleared (ON, BF, SF).
ON BF SF Fault condition
X
X
X X / O
O O
O
O
X
Everything OK
No communication
Communication, but not in data exchange
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X(blinking)
X X Configuration not OK
Remarks:Most PA instruments do not have LEDs due to power consumption and Ex restrictions.
Everything OKEverything OK
Only “ON” is lit up.Only “ON” is lit up.
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No communicationNo communication
“BF” and “ON” are lit up.“BF” and “ON” are lit up.
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No valid messages are detected on the bus.
Communication on the bus, but not in data exchangeCommunication on the bus, but not in data exchange
“BF” is blinking.“BF” is blinking.
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The device is not configured yet.
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Configuration not OKConfiguration not OK
“SF”, “BF” and “ON” are lit up.“SF”, “BF” and “ON” are lit up.
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Wrong configuration or a local problem.
AnalyzerAnalyzer
This is a PC application which extracts
The most important tool for fault finding is an Analyzer!
ppmessages from the bus and saves it in a database.
The technician can analyze the messages and come to a conclusion about the status of the instruments.
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The predictability of the PROFIBUS protocol makesthe use of a busmonitor very easy.....
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InfrastructureInfrastructure
XOld generation – brand X
New generation – ProfiTrace
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Facts and FictionFacts and FictionFacts and FictionFacts and FictionFacts and FictionFacts and FictionFacts and FictionFacts and FictionBusmonitors do not have a Busmonitors do not have a network address, but are anetwork address, but are aPhysical Physical bus loadbus load on the on the
Busmonitors do not have a Busmonitors do not have a network address, but are anetwork address, but are aPhysical Physical bus loadbus load on the on the
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yycablecable!!
yycablecable!!
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Active stations (masters) are RED passive stations (slaves) thatActive stations (masters) are RED passive stations (slaves) that
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Active stations (masters) are RED, passive stations (slaves) that exchange data have a GREEN background.Active stations (masters) are RED, passive stations (slaves) that exchange data have a GREEN background.
3 repeats, but finally a response.3 repeats, but finally a response.
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DP slave DP slave state state machinemachine
Power on/Reset
Configuration
Parameters
Diagnostics The master constantly polls the diagnostics of every slave which is not available.
When the slave gives a reaction to a diagnostic request, the parameters are transmitted.
After the parameters, the configuration is transmitted.
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Diagnostics
Data exchange
After configuration, the master requests diagnostics to check if everything has been accepted.
When the slave has accepted all the information, the master will constantly exchange data with the device.
2.1
PROFIBUS DP functions with appropriate SAPsPROFIBUS DP functions with appropriate SAPs
Functions
Data exchange
DSAP
---
SSAP
---
Check Config
Set Parameters
Get Diagnostics
Get Config
Set Global Control
Read Outputs
62 (3E)
61 (3D)
60 (3C)
59 (3B)
58 (3A)
57 (39)
62 (3E)
62 (3E)
62 (3E)
62 (3E)
62 (3E)
62 (3E)
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Read Inputs
Set Slave Address
Master-Master Commands
56 (38)
55 (37)
54 (36)
62 (3E)
62 (3E)
54 (36)
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DP slave state machine (2)DP slave state machine (2)Attention Service Sd Adr Sap Fc Len Data
(hex) (hex) (hex) | request data | SRD_HIGH | SD2 | 01 -> 22 | 3E -> 3C | 6D | | | | DL | SD2 | 01 <- 22 | 3E <- 3C | 08 | 016 | 02 05 00 FF A4 00 0A| | token | SD4 | 01 -> 01 | | | | | send data ack | SRD HIGH | SD2 | 01 -> 22 | 3E -> 3D | 5D | 017 | B8 14 01 0B A4 00 00
1. Diagnostics
| send data ack. | SRD_HIGH | SD2 | 01 > 22 | 3E > 3D | 5D | 017 | B8 14 01 0B A4 00 00| | OK | SC | | | | | | | fdl_status | SD1 | 01 -> 00 | | 49 | | | send data ack. | SRD_HIGH | SD2 | 01 -> 22 | 3E -> 3E | 7D | 002 | 13 23| | OK | SC | | | | | | | token | SD4 | 01 -> 01 | | | | | request data | SRD_HIGH | SD2 | 01 -> 22 | 3E -> 3C | 5D | | | | DL | SD2 | 01 <- 22 | 3E <- 3C | 08 | 016 | 00 0C 00 01 A4 00 0A| | token | SD4 | 01 -> 01 | | | | | request data | SRD_HIGH | SD2 | 01 -> 22 | () -> () | 7D | 004 | 00 44 67 33 | | DL | SD2 | 01 <- 22 | () <- () | 08 | 004 | 8A 08 FF DD| | fdl_status | SD1 | 01 -> 02 | | 49 | || | token | SD4 | 01 -> 01 | | | |
2. Parameters
3. Configuration 4. Diagnostics
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| request data | SRD_HIGH | SD2 | 01 -> 22 | () -> () | 7D | 004 | 00 44 67 33 | | DL | SD2 | 01 <- 22 | () <- () | 08 | 004 | 8A 08 FF DD| | fdl_status | SD1 | 01 -> 03 | | 49 | || | token | SD4 | 01 -> 01 | | | | | request data | SRD_HIGH | SD2 | 01 -> 22 | () -> () | 7D | 004 | 00 44 67 33 | | DL | SD2 | 01 <- 22 | () <- () | 08 | 004 | 8A 08 FF DD
1.2
5. Data exchange
The EndThe End
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1.0
Ing. Dennis van Booma, PROCENTEC Netherlands, [email protected]
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