lecture 19 and 20

8/12/2019 Lecture 19 and 20

1/54

Course Computer Based Automation WS 06/07 1Stephan Simons

Computer Based AutomationWinter Term 06/07

Prof. Dr. Stephan SimonsUniversity of Applied Sciences Darmstadt

Master of Science in Electrical Engineering

8/12/2019 Lecture 19 and 20

2/54


Contents of the course

1. Introduction to automation systems

2. Fundamentalsa) numerical representations, b) logical functions and operations

3. Programmable Logic Controller (PLC)a) basics, b) principle of operation, c) architecture, d) PLC family

4. PLC S7-300 with interface modules

5. Programming of a PLC

1. Overview PLC standard IEC 1131-3

2. Programming Languages for S7 family & program structure

3. Basic operations of STEP 7 in STL, LAD and FBD: Flags, Edgeevaluation, Result of logic operation & Status word, Set and resetoperations (flip flop), Timer instructions, Counter instructions,Particular instructions

4. Program organization units

5. Sequential Control Language (S7-Graph)

6. Structured Control Language (S7-SCL)

7. Indirect Addressing

6. PLC standard IEC 1131-3

today

8/12/2019 Lecture 19 and 20

3/54


Repetition of last lecture

Timer functions

On delay timer, retentive on delay timer, off delay timer, pulse timer, extended pulsetimer (symbols, example programs, timing diagrams, differences FBD, LAD, STL)

Setting the timer value as S5-Time or as hexadecimal value

Unused inputs and outputs

Example for timer functions (oscillator)

S7 Counter

Up counter, Down counter, Up and down counter (Symbols an program example for

LAD, FBD and STL)

Overview over counter operations

Signal state chart

Example for counter usage (frequency divider) Standard data types and their internal representation

Load and transfer commands

Load and transfer commands in STL; MOVE blocks in LAD & FBD

Examples for load and transfer instructions

Example loading and transfering an analog value (AI & AO)

8/12/2019 Lecture 19 and 20

4/54Course Computer Based Automation WS 06/07 4Stephan Simons

Instruction contents of lecture

Bit logic instructions

Bit logic instructions with expressions in parenthesize

Edge triggered instructions

Memory functions: Setting / Resetting bit addresses

Timer instructions

Counter instructions

Load and transfer instructions

Comparison instructions

Integer and floating-point arithmetic instructions

Floating point mathematical instructions

Jump instructions

8/12/2019 Lecture 19 and 20


S_ODT

S BI

TV BCD

R Q

T1

I0.0

S5T#2S

I0.1

MW0

MW2

Q 4.0A I 0.0

L S5T#2S Load time (2s) in ACCU 1

SD T1 Start timer T1 as a pulse

A I 0.1R T1 Reset timer T1

L T1 Load timer T1 DUAL-coded

T MW0

LC T1 Load timer T1 BCD-coded

T MW2

A T1 Query of the timer T1

= Q 4.0

S_ODT

S Q

TV BI

R BCD

T1

I0.0

S5T#2S MW0

MW2

Q 4.0

( )I0.1

On-delay Timer

FBD

LAD

STL

8/12/2019 Lecture 19 and 20


S5-TimeIf a delay time of 2 hours, 35 minutes, 24 seconds and 60 mill iseconds shall be

set use the S5 Time:

S5T#2h35m24s60ms

The possible time range is from 10ms to 2h46m30s with a resolution of 10ms.

The S5 time is transferred to the ACCU 1 with the load instruction L. The time is

stored into the ACCU 1 as a 16 bit word with the following format:

15 14 13 12 11 8 7 4 3 0Bit

102

101

100

time

basefactor for t ime base in BCDIrrelevant

00(2) 0(16) 0,01sec

01(2) 1(16) 0,1sec

10(2) 2(16) 1sec

11(2) 3(16) 10sec

Time base:Examples:

S5T#3s 2003(16) or 0300(16)

S5T#100ms 1001(16) or 0010(16)

S5T#2h46m30s 9990s 3999(16)

As a rule the smallest possible time base is used to achieve a better precision.

8/12/2019 Lecture 19 and 20


No. STL Comments

1 L 16#1350 // Load time (35s) as hex literal (const.)

2 T MW10 // Transfer to MW 10

3 A I2.1 // Start delay time with positive edge of I2.1

4 L MW10// Transfer time into ACCU 1.

5 SD T4 // Start timer T4 as an on-delay timer.

6 NOP 0 // Reset

7 L T4 // Load current time value of T4 as binary.

8 T QW4 // Transfer binary current time value to QW4.

9 NOP 0 // Current time value as BCD not used.

10 A T4 // Check signal state (binary output) of timer T4.

11 = Q4.0 // Transfer to Q4.0.

Changing the on-delay program:

The instructions no. 7 and 8 transfer the current time value of T4 as binary to

the output word QW4.

The output word QW4 consists of the two bytes QB4 and QB5

QB4 holds the more signif icant value:

QW4 [ QB4, QB5 ]

8/12/2019 Lecture 19 and 20


Choosing

the righttimer

8/12/2019 Lecture 19 and 20


S7 Counter

S_CUDCU

CD

S CV

PV CV_BCD

R Q

C1

I0.0

C#5

I0.3

QW2

QW4

Q 0.0

FBDSTL

A I 0.7 Release (only in STL)

FR C1

A I 0.0

CU C1 Count up

A I 0.1CD C1 Count down

A I 0.2

L C#5 Load counter with default value

S C1 Set counter with default value

A I 0.3

R C1 Reset counter C1

L C1 Load counter C1 DUAL-coded

T QW2

LC C1 Load counter C1 BCD-codedT QW4

A C1 Query of the counter C1

= Q 0.0

S_CUDCU Q

CD

S

PV CVR CV_BCD

C1

I0.0

C#5

I0.2

QW2

QW4

Q 0.0

LAD

( )

I0.1

I0.1

I0.3

I0.2

Counter limits: 0 999

8/12/2019 Lecture 19 and 20


S7 Counter: Signal state chart

FR

CU

CD

S

R

Q 0.0

1

2345

0

8/12/2019 Lecture 19 and 20


Load and transfer commands in STL

Load function consists of operation L (load) and an operand.

Operand is Byte, Word, DWord.

Operand is loaded into ACCU 1.

Examples for types of Operands:

L 16#F8A4 Load a constant value (Immediate addressing)

L IW16 Load an operand (Direct adrdressing)L ActValue Load a variable (Symbolic addressing)

Loading takes place in two steps:

Step 1: The content of ACCU 1 is moved into ACCU 2.

Step 2: The operand of the load instruction is loaded into ACCU 1.

Both Accumulators ACCU 1 and ACCU 3 have 32 bits each (Width of

DWORD data type).

8/12/2019 Lecture 19 and 20

12/54


Examples for loading of binary operands in STL

Loading of inputs:

L IBn // Byte

L IWn // Word

L IDn // Doubleword

Loading of outputs:

L QBn // Byte

L QWn // Word

L QDn // Doubleword

Laden from periphery:

L PIBn // Byte

L PIWn // Word

L PIDn // Doubleword

Loading of flags:

L MBn // Byte

L MWn // Word

L MDn // Doubleword

n : Address parameter e.g. 4 or 32

8/12/2019 Lecture 19 and 20

13/54


Transfer instruction T in STL T: Transfers contents of ACCU 1 to the operand

Operand: Byte, Word or Doubleword

T MW120 Contents ACCU 1 Flag (absolute addressing)

T RefValue Contents ACCU 1 Variable (symbolic addressing)

This function also works with Twisting (Exchanging byte positions).QW10 = [QB11, QB10]

QW10 consists of the two bytes QB10 and QB11.

The lower byte of ACCU 1 is stored as the most significant byte QB11. The higher byte of ACCU 1 is stored as the least significant byte QB10.

Examples for transfer instructions:

T QB15 // Transfers ACCU 1 to output byte 15.

T IW20 // Transfers ACCU 1 to process image of the inputs at// word address 20.

T MD30 // Transfers ACCU 1 to flag doubleword at address 30. T PQW320 // Transfers ACCU 1 to the periphery output word 320,

// e.g. to an analog output.

8/12/2019 Lecture 19 and 20

14/54


MOVE function in FBD and LAD

LAD

FBD

Input at IN and output at OUT can be of any elementary data type except BOOL.

Variables at input IN and output OUT may be of different data types.

8/12/2019 Lecture 19 and 20

15/54


Comparison functions in STL

Comparison

function INT DINT REAL

Equal ==I ==D ==R

Not equal I D R

Greater >I >D >R

Greater or equal >=I >=D >=R

Less

8/12/2019 Lecture 19 and 20

16/54


Comparison functions in FBD and LAD

Comparison

function INT DINT REAL

Equal CMP ==I CMP ==D CMP ==R

Not equal CMP I CMP D CMP R

Greater CMP >I CMP >D CMP >R

Greater or equal CMP >=I CMP >=D CMP >=R

Less CMP

8/12/2019 Lecture 19 and 20

17/54


Example: Comparison functions in STL

The input word IW0 is compared with the literal 120(10). If both values are

equal Bit Q4.0 shall be set to 1 , otherwise Q4.0 shall be 0.

No. STL Comments

1 A Q4.0Q4.0

IW0

120

Q4.0

2 R // Q4.0 is set to 0

3 L // load IW0 into ACCU 1

4 L // transfer IW0 from ACCU 1 into ACCU 2 and load 120// into ACCU 1

5 ==I // Compare ACCU 1 with ACCU 2 to be equal

6 S // Set Q4.0 to 1 if ACCU 1 = ACCU 2

8/12/2019 Lecture 19 and 20

18/54


Example: Comparison functions in STL

The input word IW0 is compared with the literal 120(10). If both values are

equal Bit Q4.0 shall be set to 1 , otherwise Q4.0 shall be 0.

No. STL Comments

1 A Q4.0Q4.0

IW0

120

Q4.0

2 R // Q4.0 is set to 0

3 L // load IW0 into ACCU 1

4 L // transfer IW0 from ACCU 1 into ACCU 2 and load 120// into ACCU 1

5 ==I // Compare ACCU 1 with ACCU 2 to be equal

6 S // Set Q4.0 to 1 if ACCU 1 = ACCU 2

8/12/2019 Lecture 19 and 20

19/54


Example comparison function in FBD

The input word IW0 is compared with the literal 120(10). If both values areequal Bit Q4.0 shall be set to 1 , otherwise Q4.0 shall be 0.

8/12/2019 Lecture 19 and 20

20/54


Example comparison function in LADThe input word IW0 is compared with the literal 120

(10)

. If both values areequal Bit Q4.0 shall be set to 1 , otherwise Q4.0 shall be 0.

Arithmetic functions

8/12/2019 Lecture 19 and 20

21/54


Arithmetic functions

Additional: DEC n (Decrements ACCU 1 by the value of n)INC n (Increments ACCU 1 by the value of n)

Arithmetic function INT DINT REAL

Addition +I +D +R

Subtraction -I -D -R

Multiplication *I *D *R

Division with quotient as

result

/I /D /R

Division with remainder as

result

- MOD -

Arithmetic functions in FBD and LAD

8/12/2019 Lecture 19 and 20

22/54


Arithmetic functions in FBD and LAD

No DEC or INC functions in FBD and LAD

Arithmetic function INT DINT REAL

Addition ADD_I ADD_DI ADD_R

Subtraction SUB_I SUB_DI SUB_R

Multiplication MUL_I MUL_DI MUL_R

Division with quotient as

result

DIV_I DIV_DI DIV_R

Division with remainder asresult

- MOD_DI -

8/12/2019 Lecture 19 and 20

23/54


Examples for arithmetic functions

L MW0

L MW2

+I

T MW10

L MD0

L MD2

-D

T MD10L MD0

L MD2

*R

T MD10

L MD0

L MD2

/R

T MD10

Fct. LAD FBD STL

I1-I2

I1+I2

I1*I2

I1/I2

8/12/2019 Lecture 19 and 20

24/54


Meaning of EN and ENO within functions

EN Explanation ENOEN = FALSE If EN is FALSE when calling the function, the

code-part of the function may not be executed.

In this case output ENO will be set to FALSE

upon exiting in order to indicate that the functionhas not been executed.

ENO = FALSE

EN = TRUE If EN is TRUE when calling the function, the

code-part of the function can be executed nor-

mally. In this case ENO will initially be set to

TRUE before starting the execution.

ENO = TRUE

ENO can afterwards be set to TRUE or FALSE

by instructions executed within the function

body.

ENO = individual

value

If a program or system error (as described in

Appendix E) occurs while executing the function

ENO will be reset to FALSE by the PLC.

ENO = FALSE

(error occurred)

a TRUE = logical 1, FALSE = logical 0

8/12/2019 Lecture 19 and 20

25/54


Example: Two-step controller (two-position

controller, bang-bang servo)(e.g. for temperature control)

Voltage range 0 10 V

16 bit integer value in the range 0 27648

1,5 V is equivalent to 4147 (= 1,5V * 27648) / 10V

(PIW288)

(PIW290)

(Q4.0)

w: reference value (010V)

X: actual value (010V)

Y: control variable (bit)

Xd: control deviation

Xd

= w - x

8/12/2019 Lecture 19 and 20

26/54


Two-step controller:

FBD program

(PIW288)

(PIW290)

(Q4.0)

y

8/12/2019 Lecture 19 and 20

27/54


Mathematical functions

Square, square-root

Sine, cosine, tangent

Arc sine, arc cosine, arc tangent

Exponential function to base e, natural logarithm

All these mathematical functions only work with values of the data type

REAL

!

8/12/2019 Lecture 19 and 20

28/54


Mathematical functions

Square, square-root

Sine, cosine, tangent

Arc sine, arc cosine, arc tangent

Exponential function to base e, natural logarithm

All these mathematical functions only work with values of the data typeREAL!

Conversion functions for REAL INTEGER (in STL):

lTD Conversion of INT to DINT

ITB Conversion of INT to BCD

DTR Conversion of DINT to REAL

RND Conversion of REAL to DINT with rounding to the next higher

integer number

8/12/2019 Lecture 19 and 20

29/54


Conversion

16 bit Integer

to

32 bit Integer

Conversion

32 bit Integer

to

REAL

Input Data

Integer

16 Bit

Program

algorithms

using REAL

Conversion functions INT DINT REAL

LAD FBD STL

MW12 MD20

MD20 MD28

L MW12

ITD

T MD20

L MD20

DTR

T MD28

MW12

MD20

MD20

MD28

8/12/2019 Lecture 19 and 20

30/54


Conversion function: Example

(PIW288) (PQW320)

Analog Input: PIW288 (16 bit Integer)

Analog Output: PQW320 (16 bit Integer)

Realize the following function f(x) with a PLC:

x*.y 163=

with: 0V

8/12/2019 Lecture 19 and 20

31/54


( g)

xy *16,3

V1027648int 8,2764*

int

yy 8,2764*

int xx

8,2764*16,3

8,2764

intint xy intint

*8,2764*16,3 xy intint

*157,166 xy 7)

1)

2)

3)

4)

5)

6)

R li i t t ti (I)

8/12/2019 Lecture 19 and 20

32/54


Realizing a square root extraction (I)

Realizing a square root extraction (II)

8/12/2019 Lecture 19 and 20

33/54


C i f R l 32 bit DINT

8/12/2019 Lecture 19 and 20

34/54


Conversion from Real 32 bit DINT

Round (FBD & LAD) / RND (STL): Rounds to the next integer. When the fraction

of the number is exactly between an even and uneven result, the operation chooses

the even result. Examples: +1.49 +1; 1.5 2; 2.5 2; 2.51 3

Trunc: Round with truncation of the fraction part. The result is only the integer part

of the real data. Examples: 1.6 1.

Ceil / RND+: Round to the next highest integer. This operation rounds theconverted number to the smallest integer, that is greater than or equal to the

converted integer. Examples: +1.2 +2; -1.5 -1.

Floor / RND-: Round to the next lowest integer. This operation rounds theconverted number to the largest integer, that is smaller or equal to the converted

integer. Examples: +1.5 +1; -1.5 -2.

8/12/2019 Lecture 19 and 20

35/54


Rounding Modes for the Conversion of REAL numbers

Revolution measurement: transducer

8/12/2019 Lecture 19 and 20

36/54



10 V, 20 mA, 16 mA

1000 U/min

365

500 865 1500 rpm

0 10 V

0 20 mA

4 20 mA

10 V : 1000 rpm = 0,01 V/U/rpm

365 U/min 3,65 V

Internal representation of analog value in case ofbipolar measurement range

8/12/2019 Lecture 19 and 20

37/54


bipolar measurement rangeIncrements Voltage

measurement range

Current

measurement range

Range

dec. hex. 10 V 20 mA

32767 7FFF 11,851 V 23,70 mA

32512 7F00

32511 7EFF 11,759 V 23,52 mA

27649 6C01

27648 6C00 10 V 20 mA

20736 5100 7,5 V 15 mA

1 1 361,7 V 723,4 nA

0 0 0 V 0 mA

1 FFFF -361,7 V -723,4 nA

20736 AF00 7,5 V 15 mA

27648 9400 10 V 20 mA

27649 93FF

32512 8100 11,759 V 23,52 mA32513 80FF

32768 8000 11,851 V 23,70 mAUnderflow

Underrange

Rated range

Overange

Overflow

Internal representation of analog value in case ofunipolar measurement range

8/12/2019 Lecture 19 and 20

38/54


unipolar measurement range

System Voltage

measurement range

Current measurement range Range

dez. hex. 0..10 V 0..20 mA 4..20 mA

32767 7FFF 11,851 V 23,70 mA 22,96 mA

32512 7F00

32511 7EFF 11,759 V 23,52 mA 22,81 mA

27649 6C01

27648 6C00 10 V 20 mA 20 mA20736 5100 7,5 V 15 mA 16 mA

1 1 361,7 V 723,4 nA 4 mA + 578,7 nA

0 0 0 V 0 mA 4 mA

1 FFFF4864 ED00 3,52 mA 1,185 mA

4865 ECFF

32768 8000

Negative

values not

possible

Negative values

not possibleUnderflow

UnderrangeNegative

valuesnot

possible

Rated

range

Overrange

Overflow

Revolution measurement AD converter

8/12/2019 Lecture 19 and 20

39/54


Revolution measurement AD converter

0 27648

0 10 V

020 mA

4 20 mA

13824

12

10

5


8/12/2019 Lecture 19 and 20

40/54



10 V, 20 mA, 16 mA

1000 U/min

365

500 865 1500 rpm

0 27648 Incr.13824

1000

10092

Table for normalization

8/12/2019 Lecture 19 and 20

41/54


Table for normalization

System Voltage

measurement

range

Current measurement range Range

dez. hex. 10 V 0..10 V 20 mA 0..20 mA 4..20 mA

27648 6C00 10 V 10 V 20 mA 20 mA 20 mA0 0 0 V 0 V 0 mA 0 mA 4 mA

27648 9400 10 V 20 mA

Rated

range

Task: Reading and normalizing of an analog value

8/12/2019 Lecture 19 and 20

42/54


Task: Reading and normalizing of an analog value

Acquire an analog value in the range of 0V to 10V with an analog input

module in rack 0 (central unit), slot 6 (PIW288), map it onto the range 100 to

1000 as a REAL value and store the result as MD10!

L PIW 288 // Analog value input 0 to 10 V contains 0 to 27648 integers (16 Bit)

ITD // Value of integer (16 Bit) converted into integer (32 Bit)

DTR // Value of integer (32 Bit) converted into a real number

L 2.7648e+4

/R // Division with real number 27648 mapping value to range 0 to 1

L 9.000e+2

*R // Multiplication with real number 900 (1000-100) -> range 0 to 900

L 1.000e+2

+R // Addition with real number 100 (Offset) range 100 to 1000

T MD10 // Normalized value 100 to 1000 in real format

Analog value conversion and processing

8/12/2019 Lecture 19 and 20

43/54


Analog value conversion and processing

835 rpm 3,65 V 10092 Incr

10092(INT) 10092(DINT) 10092,0

10092,0 *2,2 22202,4

22202,4 22202(DINT) 22202 Incr

22202 Incr 8,03 V 1303 rpm

Transducer

A/D-Converter

L PIWn

ITD DTR

Programmed algortihm

RND T PQWn

ActuatorD/A-Converter

Jump instructions

8/12/2019 Lecture 19 and 20

44/54


Jump instructions

Unconditionally jumps: Are executed always no matter of a condition.

Conditionally jumps: Are executed only if the condition is fullfiled.

LOOP: instruction to call a program segment multiple times (only in STL)

Jump unconditional

8/12/2019 Lecture 19 and 20

45/54


Jump unconditionalLAD FBD STL

Jumps conditional

8/12/2019 Lecture 19 and 20

46/54


Jumps conditionalLAD FBD STL

All jump instructions in STL

8/12/2019 Lecture 19 and 20

47/54


All jump instructions in STL

Unconditionally jumps:

JU label Jump Unconditional

JL label Jump to Labels

Jumps based on RLO: JC label Jump if RLO = 1

JCN label Jump if RLO = 0

JCB label Jump if RLO = 1 with BR

JNB label Jump if RLO = 0 with BR

Jumps based on another bit in the status

word: JBI label Jump if BR = 1

JNBI label Jump if BR = 0

JO label Jump if OV = 1

JOS label Jump if OS = 1

Jumps based on the result of a

calculation:

JZ label Jump if Zero

JN label Jump if Not Zero

JP label Jump if Plus JM label Jump if Minus

JPZ label Jump if Plus or Zero

JMZ label Jump if Minus or Zero

JUO label Jump if Unordered

Loop instruction

LOOP label call a program

segment multiple

times

Jump distributor: JL

8/12/2019 Lecture 19 and 20

48/54


p

The jump distributor allows specific (calculated) jumping to aprogram section in the block conditional on a number of positions.

It works in conjunction with a list of JU jump functions followingimmediately the JL instruction.

The list can contain up to 255 entries.

The label of the JL instruction points to the end of the list.

L Number_of_jump;

JL End; // jump label points to the first statement after the list

JU L0; // jump to L0 if Number_of_jump = 0

JU L1; //jump to L1 if Number_of_jump = 1

JU Lx; // jump to Lx if Number_of_jump = x

End:

LOOP Jump

8/12/2019 Lecture 19 and 20

49/54


p

L NumberOffLoops;

Next: T ActLoopCountNo;

L ActLoopCountNo;

LOOP Next;

The loop jump LOOP allows a simplified programming of program loops.

When processed, LOOP first decrements the contents of ACCU 1 by 1.

If the value is not zero afterwards, the jump is executed to the jump labelspecified.

If the value is zero, the jump is not executed and the next statement isprocessed.

The start value in ACCU 1 thus corresponds to the number of program loopsto be passed. This value has to be stored in a loop counter.

Example: Using the jump instruction to

8/12/2019 Lecture 19 and 20

50/54


p g j p

restrict an analog value

(PIW288) (PQW320)

Internal representation of the limits:

Lower limit: 0V 0

Upper limit: 8V (8V * 27648) / 10 V = 22118

Restriction of an analog value: STL program

8/12/2019 Lecture 19 and 20

51/54


(PIW288) (PQW320)

Restriction of an analog value: FBD program (I)

8/12/2019 Lecture 19 and 20

52/54


Restriction of an analog value: FBD program (II)

8/12/2019 Lecture 19 and 20

53/54


Instruction contents of lecture

8/12/2019 Lecture 19 and 20

54/54


Bit logic instructions

Bit logic instructions with expressions in parenthesize

Edge triggered instructions

Memory functions: Setting / Resetting bit addresses

Timer instructions

Counter instructions

Load and transfer instructions

Comparison instructions

Integer and floating-point arithmetic instructions

Floating point mathematical instructions

Jump instructions

lecture 19 and 20

Documents