Automation Direct Stellar SR55 Series User Manual

Chapter 5: Communications
Page 5–5Stellar
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SR55 Series Soft Starter User Manual – 1st Ed, Rev F – 09/18/2019
modbus serial CommuniCaTions (ConTinued)
supporTed funCTions
Modbus RTU specification defines the functions used to access different types of data.
• SR55 parameters are defined as holding type registers.
• For Modbus RTU/TCP Client devices that use Modicon style addressing, place a 4 as the high
digit followed by the Modbus address defined in the parameter mapping table. Note that
SR55 Modbus addressing starts at zero; not 1 as some devices do.
• SR55 32-bit parameters are High Word / Low Word in Modbus format.
The following services are available:
read holding regisTers
Description: reading register blocks of holding register type (block R/W limited to 8 registers).
• Function code: 03
Modbus Function 03 Transaction Table
Query Response
Field Hex Byte Field Hex Byte
Slave address 01 Slave address 01
Function 03 Function 03
Start address Hi 00 Byte count 02
Start address Lo 01 Data Hi 01
No of registers Hi 00 Data Lo 2C
No of registers Lo 01 CRC Lo B8
CRC Lo D5 CRC Hi 09
CRC Hi CA
Before writing to the SR55, initiate several Modbus Reads to ensure that the master’s
addressing and configuration are correct.
WriTe single regisTer
Description: writing in a single register of the holding type.
• Function code: 06
Modbus Function 06 Transaction Table
Query Response
Field Hex Byte Field Hex Byte
Slave address 01 Slave address 01
Function 06 Function 06
Address Hi 00 Address Hi 02
Address Lo 0C Address Lo 0C
Force data Hi 00 Force data Hi 00
Force data Lo 09 Force data Lo 09
CRC Lo 48 CRC Lo 88
CRC Hi 0C CRC Hi 77

Automation Direct Stellar SR55 Series Specifications

General

Brand	Automation Direct
Model	Stellar SR55 Series
Category	Controller
Language	English