GE 489 - Manual (Page 168)

6-6 489 Generator Management Relay GE Multilin
6.2 MODBUS FUNCTIONS 6 COMMUNICATIONS
6
6.2.7 FUNCTION CODE 16: STORE MULTIPLE SETPOINTS
Modbus Implementation: Preset Multiple Registers
489 Implementation:
Store Multiple Setpoints
This function code allows multiple Setpoints to be stored into the 489 memory. Modbus "registers" are 16-bit (two byte) val-
ues transmitted high order byte first. Thus all 489 setpoints are sent as two bytes. The maximum number of Setpoints that
can be stored in one transmission is dependent on the slave device. Modbus allows up to a maximum of 60 holding regis-
ters to be stored. The 489 response to this function code is to echo the slave address, function code, starting address, the
number of Setpoints stored, and the CRC.
MESSAGE FORMAT AND EXAMPLE
Request slave 11 to store the value 01F4 to Setpoint address 1180 and the value 0001 to setpoint address 1181. After the
transmission in this example is complete, 489 slave 11 will have the following setpoints information stored:
ADDRESS DATA
1180 01F4
1181 0001
MASTER TRANSMISSION: BYTES EXAMPLE (hex):
SLAVE ADDRESS 1 0B message for slave 11
FUNCTION CODE 1 10 store setpoints
DATA STARTING ADDRESS 2 11 80 data starting at 1180
NUMBER OF SETPOINTS 2 00 02 2 setpoints (4 bytes total)
BYTE COUNT 1 04 2 registers = 4 bytes
DATA 1 2 01 F4 data for address 1180
DATA 2 2 00 01 data for address 1181
CRC 2 9B 89 CRC calculated by the master
SLAVE RESPONSE: BYTES EXAMPLE (hex):
SLAVE ADDRESS 1 0B response message from slave 11
FUNCTION CODE 1 10 store setpoints
DATA STARTING ADDRESS 2 11 80 data starting at 1180
NUMBER OF SETPOINTS 2 00 02 2 setpoints (4 bytes total)
CRC 2 45 B6 CRC calculated by the slave