GE b30 Communications Guide

CHAPTER 2: MODBUS COMMUNICATION MODBUS FUNCTION CODES
UR FAMILY – COMMUNICATIONS GUIDE 2-5
2
2.2.3 Execute operation (function code 05h)
This function code allows the master to perform various operations in the relay. Available operations are shown in the
summary table below.
The following table shows the format of the master and slave packets in Modbus RTU. Modbus TCP/IP ADUs have a MBAP
instead of slave address, and CRC is in another stack layer. The example shows a master device requesting the slave
device 11h (17 decimal) to perform a reset. The high and low code value bytes always have the values “FF” and “00”
respectively and are a remnant of the original Modbus definition of this function code.
Table 2-6: Master and slave device packet transmission example
Table 2-7: Summary of operation codes for function 05h
2.2.4 Store single setting (function code 06h)
This function code allows the master to modify the contents of a single setting register in an relay. The following table
shows the format of the master and slave packets in Modbus RTU. Modbus TCP/IP ADUs have a MBAP instead of slave
address, and CRC is in another stack layer. The example shows a master device storing the value 200 at memory map
address 4051h to slave device 11h (17 dec).
NUMBER OF REGISTERS - high 00 DATA #1 - low 28
NUMBER OF REGISTERS - low 03 DATA #2 - high 01
CRC - low A7 DATA #2 - low 2C
CRC - high 4A DATA #3 - high 00
DATA #3 - low 00
CRC - low 0D
CRC - high 60
Master transmission Slave response
Packet format Example (Hex) Packet format Example (Hex)
SLAVE ADDRESS 11 SLAVE ADDRESS 11
FUNCTION CODE 05 FUNCTION CODE 05
OPERATION CODE - high 00 OPERATION CODE - high 00
OPERATION CODE - low 01 OPERATION CODE - low 01
CODE VALUE - high FF CODE VALUE - high FF
CODE VALUE - low 00 CODE VALUE - low 00
CRC - low DF CRC - low DF
CRC - high 6A CRC - high 6A
Operation code
(Hex)
Definition Description
0000 NO OPERATION Does not do anything
0001 RESET Performs the same function as the
front panel RESET key
0005 CLEAR EVENT RECORDS Performs the same function as the
front panel CLEAR EVENT RECORDS menu
command
0006 CLEAR OSCILLOGRAPHY Clears all oscillography records
1000 to 103F VIRTUAL IN 1 to 64 ON/OFF Sets the states of Virtual Inputs 1 to 64 either “ON” or “OFF”
Master transmission Slave response
Packet format Example (Hex) Packet format Example (Hex)

GE b30 Specifications

General

Brand	GE
Model	b30
Category	Relays
Language	English