using modbus communication to control step motors

October 9, 2013

Jeff Kordik

Development, Application Support & Marketing Concepts

2Applied Motion Products Confidential and Proprietary

Reproduction by any method or unauthorized circulation is prohibited without prior approval.

Why Modbus?

Modbus is a standard data transfer protocol that is supported by many PLCs and HMIs

By supporting Modbus on our products, applications using PLCs or HMIs can easily

• command motion• query status• set drive parameters• launch Q segments

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How does it work?

PLC is the master, drive is the slave Internal PLC or HMI memory is first loaded with

parameters to be sent to Modbus registers in the drive The drive (slave) address is specified The data range to transfer (how many bytes and what

location) is then set and the data is transferred• Is it a good idea to have related functions mapped to adjacent

register addresses• For example: speed, accel, decel and distance

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Two Kinds of Modbus

Modbus/RTU Family:• STM17/23/24• SWM24• ST5/10• STAC6

Target Launch Date: December, 2013 Modbus/TCP in early 2014

• STM23/24• SWM24• ST• STAC5

RS-232/485

Ethernet

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About Modbus

Modbus standards are established by The Modbus Organization

Applied Motion Products is a proud member of The Modbus Organization

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Modbus Stepper Products

These Modbus-enabled products were introduced to the market on December 20, 2013

STM24QF integrated step drive+motor• Available with RS-232 or RS-485 communication• Stored Q programming capability for distributed

intelligence

SWM24QF integrated step drive+motor• IP65 rated for harsh environments• Available with RS-232 communication• Stored Q programming capability for distributed

intelligence

Encoder feedback for closed loop

control

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Modbus Data Transfer Example

Step 1: Setting up a Point to Point Move

Accel rateV1300

Decel rateV1301

SpeedV1302

DistanceV1303/4

Accel rate 40001

Decel rate 40002

Speed 40003

Distance 40004/5

PLC memory Modbus registers SCL register mapping

AC

DE

VE

DI

PLC DSP

RS-232RS-485

OrEthernet

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Modbus Data Transfer Example

Step 2: Starting a Point to Point Move

CommandV1305 Command 40006

PLC memory Modbus registers SCL register mapping

FL

PLC DSP

RS-232RS-485

OrEthernet

Command register will contain a bit for each type of move:FL, FP, SH, FS, FE, CJ etc

And other commands such as:ST, SJ

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PLC Program (Ladder Logic)

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Reproduction by any method or unauthorized circulation is prohibited without prior approval.

PLC Program (Ladder Logic)

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Reproduction by any method or unauthorized circulation is prohibited without prior approval.

Modbus

Application Support Objective: make sure our products are easy to apply with the most popular and cost effective PLCs and HMIs

Marketing Objective: engage our channel partners to pair our controls with their PLCs and HMIs

Popular Modbus PLCs in North America

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Schneider/Modicon

Modicon, invented Modbus Owned by Schneider One of world’s best selling

PLC lines

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Automation Direct/Direct Logic

Popular online automation retailer

Have own PLC line, lowest cost

Application note for controlling Applied Motion Products Modbus drives by Jeff Kordik is available at http://www.applied-motion.com/support/application-notes

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Reproduction by any method or unauthorized circulation is prohibited without prior approval.

Omron

Making big push into U.S. market

July 2013: introduced “Easy Modbus Master”

Popular Modbus HMIs in North America

17Applied Motion Products Confidential and Proprietary

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Proface

Sold by many Applied Motion channel partners

Powerful color touchscreen HMI with RS-232 and Ethernet

Application note for controlling Applied Motion Products Modbus drives by Jeff Kordik is available at http://www.applied-motion.com/support/application-notes

18Applied Motion Products Confidential and Proprietary

Reproduction by any method or unauthorized circulation is prohibited without prior approval.

Beijer

Sold by many Applied Motion channel partners

Powerful color touchscreen HMI with RS-232 and Ethernet

Application note for controlling Applied Motion Products Modbus drives by Jennifer Gaona is available at http://www.applied-motion.com/support/application-notes

19Applied Motion Products Confidential and Proprietary

Reproduction by any method or unauthorized circulation is prohibited without prior approval.

Automation Direct

Popular online automation retailer

EA1-T6CL 6” color touchscreen HMI is a good value.

Application note for controlling Applied Motion Products Modbus drives by Jeff Kordik is available at http://www.applied-motion.com/support/application-notes