Function Code 16: Store Multiple Setpoints - GE 489 Instruction Manual

6 COMMUNICATIONS
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:
SLAVE ADDRESS
FUNCTION CODE
DATA STARTING ADDRESS
NUMBER OF SETPOINTS
BYTE COUNT
DATA 1
DATA 2
CRC
SLAVE RESPONSE:
SLAVE ADDRESS
FUNCTION CODE
DATA STARTING ADDRESS
NUMBER OF SETPOINTS
CRC
GE Power Management

6.2.7 FUNCTION CODE 16: STORE MULTIPLE SETPOINTS

BYTES EXAMPLE (hex):
1 0B message for slave 11
1 10 store setpoints
2 11 80 data starting at 1180
2 00 02 2 setpoints (4 bytes total)
1 04 2 registers = 4 bytes
2 01 F4 data for address 1180
2 00 01 data for address 1181
2 9B 89 CRC calculated by the master
BYTES EXAMPLE (hex):
1 0B response message from slave 11
1 10 store setpoints
2 11 80 data starting at 1180
2 00 02 2 setpoints (4 bytes total)
2 45 B6 CRC calculated by the slave
489 Generator Management Relay
6.2 SUPPORTED MODBUS FUNCTIONS
6
6-7