2 function code 05h - execute operation, 2 function code 05h – execute operation – GE Industrial Solutions Entellisys 4.0 Integrator's Guide User Manual

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Modbus® protocol implementation

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2.5.2 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

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

SLAVE RESPONSE

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