Hor to programmm AC800M Modbus MBWrite command so command only goes on data change
Hi,
We have RTU560 which does not support Function code 15 for multiple coil write, it only support function code 5- which required MBWrite for every Digital commands.
We have total 200 Digital command in one RTU, 200 MBWrite blocks will increase the system load.
can you please help us how to configure AC800M program so that the write command , will be issues to digital outputs which signals are getting changed.
Regards
Rajeesh
We have RTU560 which does not support Function code 15 for multiple coil write, it only support function code 5- which required MBWrite for every Digital commands.
We have total 200 Digital command in one RTU, 200 MBWrite blocks will increase the system load.
can you please help us how to configure AC800M program so that the write command , will be issues to digital outputs which signals are getting changed.
Regards
Rajeesh
Asked 2 months ago
Answers
0
The MBWrite Function Block is edge triggered and the address can be changed dynamically. You only need one MBWrite. Set the start address and then trigger the Write command.
However, something seems wrong about only being able to write one coil. Single shot write commands is not really how Modbus is supposed to work. Remember that you can write multiple "coils" by writing Registers to the same address.
However, something seems wrong about only being able to write one coil. Single shot write commands is not really how Modbus is supposed to work. Remember that you can write multiple "coils" by writing Registers to the same address.
0
We can reduce load / no of blocks by writing the logic in ST.
Refer the below link in which Modbus codes are written in ST code
https://forum-controlsystems.abb.com/...
Refer the below link in which Modbus codes are written in ST code
https://forum-controlsystems.abb.com/...
Answered 2 months ago
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