Fairford agility Series, User Manual, Page: 42 / 127

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agility TM Series Soft Start User Manual
MAN-AGY-001. Version 04. 21/09/2018
CRC
The used method is the CRC-16 (Cyclic Redundancy Check). This field is formed by two bytes; where first
the least significant byte is transmitted (CRC-), and then the most significant (CRC+). The CRC calculation
form is described in the Modbus RTU protocol specification.
Supported Functions
Modbus RTU specification defines the functions used to access different types of data.
• agility
TM
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 agility
TM
Modbus addressing starts at zero; not 1 as some devices do.
• agility
TM
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 example
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
Write Single Register
Description: writing in a single register of the holding type.
• Function code: 06 example
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
Data Hi 00 Data Hi 00
Data Lo 09 Data Lo 09
CRC Lo 48 CRC Lo 88
CRC Hi 0C CRC Hi 77
Communication (continued)