B-6 C70 Capacitor Bank Protection and Control System GE MultilinB.2 MODBUS FUNCTION CODES APPENDIX BBB.2.5 STORE MULTIPLE SETTINGS (FUNCTION CODE 10H)This function code allows the master to modify the contents of a one or more consecutive setting registers in a relay. Settingregisters are 16-bit (two byte) values transmitted high order byte first. The maximum number of setting registers that can bestored in a single packet is 60. The following table shows the format of the master and slave packets in Modbus RTU. Mod-bus TCP/IP ADUs have a MBAP instead of slave address, and CRC is in another stack layer. The example shows a masterdevice storing the value 200 at memory map address 4051h, and the value 1 at memory map address 4052h to slavedevice 11h (17 decimal).B.2.6 EXCEPTION RESPONSESProgramming or operation errors usually happen because of illegal data in a packet. These errors result in an exceptionresponse from the slave. The slave detecting one of these errors sends a response packet to the master with the high orderbit of the function code set to 1.The following table shows the format of the master and slave packets in Modbus RTU. Modbus TCP/IP ADUs have aMBAP instead of slave address, and CRC is in another stack layer. The example shows a master device sending theunsupported function code 39h to slave device 11h.Table B–8: MASTER AND SLAVE DEVICE PACKET TRANSMISSION EXAMPLEMASTER TRANSMISSION SLAVE RESPONSEPACKET FORMAT EXAMPLE (HEX) PACKET FORMAT EXAMPLE (HEX)SLAVE ADDRESS 11 SLAVE ADDRESS 11FUNCTION CODE 10 FUNCTION CODE 10DATA STARTING ADDRESS - hi 40 DATA STARTING ADDRESS - hi 40DATA STARTING ADDRESS - lo 51 DATA STARTING ADDRESS - lo 51NUMBER OF SETTINGS - hi 00 NUMBER OF SETTINGS - hi 00NUMBER OF SETTINGS - lo 02 NUMBER OF SETTINGS - lo 02BYTE COUNT 04 CRC - lo 07DATA #1 - high order byte 00 CRC - hi 64DATA #1 - low order byte C8DATA #2 - high order byte 00DATA #2 - low order byte 01CRC - low order byte 12CRC - high order byte 62Table B–9: MASTER AND SLAVE DEVICE PACKET TRANSMISSION EXAMPLEMASTER TRANSMISSION SLAVE RESPONSEPACKET FORMAT EXAMPLE (HEX) PACKET FORMAT EXAMPLE (HEX)SLAVE ADDRESS 11 SLAVE ADDRESS 11FUNCTION CODE 39 FUNCTION CODE B9CRC - low order byte CD ERROR CODE 01CRC - high order byte F2 CRC - low order byte 93CRC - high order byte 95
