Modbus RTU Serial Enabled/Disabled by Script

[HannPark]

Hi guys...

is there a way to activate and deactivate the Modbus RTU Serial 1 by an event script?, cuz´I want to use an object for doing this from the visualization without using the administrator account 

B.R

[admin]

What is the use case for that?

[HannPark]

Hi admin,

I'm trying to use 2 Modbus Masters writing in KNX(The LM and an external one)reading common devices but clearly not at the same time, so the master change should be done by the final user, switching between them without getting access over the LM config. That's why I want to set up a switch in user's visualization for make this change.

B.R

[Daniel]

This is not the best approach. You should make one device talking to slave and the other two masters should exchange data in another way. LM can be also modbus slave.

[HannPark]

Thanks Daniel,

But what happened if I had 2 masters reading same devices?, in Modbus that's imposible but...you can do it if you turn off one master when the other one is working, as I see.. that's like a redundant modbus network, that's the thing that I wanna get... it's easy from the admin account cuz' you just go to the modbus tab and disable RTU and it's done...but the tricky thing is to do it from the visualization...

[admin]

Use this event script to emulate a web request to enable/disable RTU. Attach it to a boolean object.

Code:

value = event.getvalue() require('uci') require('json') function getvar()   return 'config-save' end function json.data()   return { enabled = value } end dofile('/lib/genohm-scada/plugins/modbus/web.lua')

[HannPark]

Thank u so much admin, it totally works!

B.R

[Kilogica]

Sorry, tried that script but it makes this error:

Code:

/lib/genohm-scada/plugins/modbus/web:0: attempt to index global 'ngx' (a nil value) stack traceback: /lib/genohm-scada/plugins/modbus/web: in function 'restart' /lib/genohm-scada/plugins/modbus/web: in function </lib/genohm-scada/plugins/modbus/web:0> /lib/genohm-scada/plugins/modbus/web: in function </lib/genohm-scada/plugins/modbus/web:0> [C]: in function 'dofile' User script:14: in main chunk

[admin]

Add this before the dofile call:

Code:

ngx = { sleep = os.sleep }

[Kilogica]

Thanks!

[EjvindHald]

On firmware 2025.12 (20251204), disabling a Modbus RTU device — via the RTU settings checkbox, via webrequest('general','plugin',{plugin='modbus',request='config-save',data={enabled=false}}), or via the original dofile('/lib/genohm-scada/plugins/modbus/web.lua') method (which correctly invokes the plugin's internal restart function) — correctly persists the disabled state in all three cases, but the live polling process continues scanning the device regardless, generating timeout errors at the normal poll interval.

Also, pressing the 'RTU Scan' button used to give an error message (can't remember the correct wording) when all RTU's are disabled. But now it just shows a new window for selection scanning options as if the RTU were enabled.