7–8 PQM POWER QUALITY METER – INSTRUCTION MANUAL
MODBUS FUNCTIONS CHAPTER 7: MODBUS COMMUNICATIONS
7.2.4 Function Code
05 – Broadcast
Command
Modbus Implementation: Force Single Coil
PQM Implementation: Execute Operation
This function code allows the master to request all PQMs on a particular communications
link to Clear All Demand Data. The PQM will recognize a packet as being a broadcast
command if the SLAVE ADDRESS is transmitted as 0. Below is an example of the Broadcast
Command to Clear All Demand Data.
MESSAGE FORMAT AND EXAMPLE:
Clear All Demand Data on all PQMs (operation code 34).
Table 7–3: Master/Slave Packet Format for Broadcast Command
MASTER TRANSMISSION BYTES EXAMPLE DESCRIPTION
SLAVE ADDRESS 1 00
broadcast command
(address = 0)
FUNCTION CODE 1 05 execute operation
OPERATION CODE 2 00 22
clear all demand data
(operation code 34)
CODE VALUE 2 FF 00 perform function
CRC 2 2D E1 CRC error code
SLAVE RESPONSE BYTES EXAMPLE DESCRIPTION
Slave does not respond back to the master.
Courtesy of NationalSwitchgear.com
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