GE Power Quality Meter Series, Instruction Manual

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GE Power Management PQM Power Quality Meter 7-11
7 MODBUS COMMUNICATIONS 7.2 MODBUS FUNCTIONS
7
7.2.9 FUNCTION CODE 16 - PERFORMING COMMANDS
Some PLCs may not support execution of commands using function code 5 but do support storing multiple set-
points using function code 16. To perform this operation using function code 16 (10H), a certain sequence of
commands must be written at the same time to the PQM. The sequence consists of: Command Function regis-
ter, Command operation register and Command Data (if required). The Command Function register must be
written with the value of 5 indicating an execute operation is requested. The Command Operation register must
then be written with a valid command operation number from the list of commands shown in the memory map.
The Command Data registers must be written with valid data if the command operation requires data. The
selected command will be executed immediately upon receipt of a valid transmission.
MESSAGE FORMAT AND EXAMPLE:
Perform a reset on PQM (operation code 1).
Table 7–8: MASTER/SLAVE PACKET FORMAT FOR PERFORMING COMMANDS
MASTER TRANSMISSION BYTES EXAMPLE DESCRIPTION
SLAVE ADDRESS 1 11 message for slave 17
FUNCTION CODE 1 10 store multiple setpoints
DATA STARTING ADDRESS 2 00 80 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 00 05 data for address 0080
DATA 2 2 00 01 data for address 0081
CRC 2 B0 D6 CRC error code
SLAVE RESPONSE BYTES EXAMPLE DESCRIPTION
SLAVE ADDRESS 1 11 message from slave 17
FUNCTION CODE 1 10 store multiple setpoints
DATA STARTING ADDRESS 2 00 80 setpoint address 00 80
NUMBER OF SETPOINTS 2 00 02 2 setpoints
CRC 2 46 7A CRC error code