IoDrvModbusTCP - Programmatically change Unit ID

2022-09-26T16:41:35.659000Z

Hi i-campbell, I tried adding the 'slave COM port' under the TCP Slave - however there was no SlaveAddress - the only thing was an output showing the usiUnitID - however there didn't appear to be a way to set this in the code.

IoDrvModbusTCP - Programmatically change Unit ID

2022-09-24T08:52:51.957000Z

The solution I suugested was for tcp. Take a look at the red circled 3 in the link.
If it has more than one unit ID, the TCP slave is acting as a gateway, and you add the unit IDs as serial com devices beneath the tcp slave. A bit counterintuitive for sure.

IoDrvModbusTCP - Programmatically change Unit ID

2022-09-23T14:03:29.977000Z

Thanks for the suggestion, unfortunately it is Modbus TCP, the SlaveAddress is for Modbus RTU and isn't present on the communication settings for Modbus TCP.

IoDrvModbusTCP - Programmatically change Unit ID

2022-09-23T13:35:21.322000Z

so if you have your device tree lain out like the red circle with the three in it here: https://content.helpme-codesys.com/en/CODESYS%20Modbus/_mod_general.html

Then you could access it like:
change it with RTU_Slave1.SlaveAddress:=2;

Not sure if you need to set RTU_Slave1.Enable to false first or not to be allowed to change it.

IoDrvModbusTCP - Programmatically change Unit ID

2022-09-23T13:14:11.473000Z

Hello,

I have a project with a package controller fitted to a machine - it has a feature where the overall package parameters are available via Unit ID 100 - this is static. The machine specific details are then available via a different Unit ID.
When several machines are plugged into each other, these IDs will increment - so the package controller (an IPC) will respond for the entire package via Unit ID 100, but if I want to check details for machine 1, it will be Unit ID 1, for machine 2 it would be Unit ID 2 etc.

The PLC I am putting together will allow control over the package, there is also a HMI - I want the user to be able to change the ID number so they can view individual machines as well - without having to add lots of individual IoDrvModbusTCP devices with the Unit ID set on each one.

I have looked at the library but can't see a way to change the Unit ID programmatically - so thought I would check and see if I am missing something and there is another way possibly?

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