GE Power Quality Meter Series, Instruction Manual

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7-10 PQM Power Quality Meter GE Power Management
7.2 MODBUS FUNCTIONS 7 MODBUS COMMUNICATIONS
7
7.2.8 FUNCTION CODE 16 – STORE MULTIPLE SETPOINTS
Modbus Implementation: Preset Multiple Registers
PQM Implementation: Store Multiple Setpoints
This function code allows multiple Setpoints to be stored into the PQM memory. Modbus "registers" are 16 bit
(two byte) values transmitted high order byte first. Thus all PQM setpoints are sent as two bytes. The maxi-
mum 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 registers to be stored. The PQM allows 60 registers to be stored in one
transmission. The PQM 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 1028 and the value 2710 to setpoint address
1029. After the transmission in this example is complete, PQM slave 11 will have the following Setpoints infor-
mation stored:
Address Data
1028 01F4
1029 2710
Table 7–7: MASTER/SLAVE PACKET FORMAT FOR FUNCTION CODE 10H
MASTER TRANSMISSION BYTES EXAMPLE DESCRIPTION
SLAVE ADDRESS 1 11 message for slave 17
FUNCTION CODE 1 10 store setpoints
DATA STARTING ADDRESS 2 10 28 setpoint address 1028
NUMBER OF SETPOINTS 2 00 02 2 setpoints = 4 bytes total
BYTE COUNT 1 04 4 bytes of data
DATA 1 2 01 F4 data for setpoint address 1028
DATA 2 2 27 10 data for setpoint address 1029
CRC 2 33 23 CRC error code
SLAVE RESPONSE BYTES EXAMPLE DESCRIPTION
SLAVE ADDRESS 1 11 message from slave 17
FUNCTION CODE 1 10 store setpoints
DATA STARTING ADDRESS 2 10 28 setpoint address 1028
NUMBER OF SETPOINTS 2 00 02 2 setpoints
CRC 2 C7 90 CRC error code