GE Multilin C60 Breaker Protection System B-5
APPENDIX B B.2 MODBUS FUNCTION CODES
B
B.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 Sum-
mary of operation codes 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.
B.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. Setting registers are
always 16 bit (two byte) values transmitted high order byte first. 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).
Table B–5: MASTER AND SLAVE DEVICE PACKET TRANSMISSION EXAMPLE
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
Table B–6: SUMMARY OF OPERATION CODES FOR FUNCTION 05H
OPERATION
CODE (HEX)
DEFINITION DESCRIPTION
0000 NO OPERATION Does not do anything.
0001 RESET
Performs the same function as the
faceplate RESET key.
0005 CLEAR EVENT RECORDS
Performs the same function as the
faceplate 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”.
Table B–7: MASTER AND SLAVE DEVICE PACKET TRANSMISSION EXAMPLE
MASTER TRANSMISSION SLAVE RESPONSE
PACKET FORMAT EXAMPLE (HEX) PACKET FORMAT EXAMPLE (HEX)
SLAVE ADDRESS 11 SLAVE ADDRESS 11
FUNCTION CODE 06 FUNCTION CODE 06
DATA STARTING ADDRESS - high 40 DATA STARTING ADDRESS - high 40
DATA STARTING ADDRESS - low 51 DATA STARTING ADDRESS - low 51
DATA - high 00 DATA - high 00
DATA - low C8 DATA - low C8
CRC - low CE CRC - low CE
CRC - high DD CRC - high DD