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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.