GE Industrial Solutions Entellisys Integrator’s Guide - Manual (Page 11)

Modbus ® protocol implementation 11
1.1.5.2 Function Code 05H – Execute Operation
This function code allows the master to perform various operations in the CPU.
The following table shows the format of the master and slave packets. The example shows a
master device requesting the slave device 11H (17 dec) to perform a reset. The hi and lo CODE
VALUE bytes always have the values ‘FF’ and ‘00’ respectively and are a remnant of the original
Modbus definition of this function code.
Master and Slave Device Packet Transmission Example
SLAVE RESPONSE
PACKET FORMAT EXAMPLE (HEX)
SLAVE ADDRESS 11
FUNCTION CODE 04
BYTE COUNT 06
DATA #1 - hi 00
DATA #1 - lo 28
DATA #2 - hi 01
DATA #2 - lo 2C
DATA #3 - hi 00
DATA #3 - lo 00
CRC - lo 0D
CRC - hi 60
MASTER TRANSMISSION
PACKET FORMAT EXAMPLE (HEX)
SLAVE ADDRESS 11
FUNCTION CODE 05
OPERATION CODE - hi 00
OPERATION CODE - lo 01
CODE VALUE - hi FF
CODE VALUE - lo 00
CRC - lo DF
CRC - hi 6A