Design question MODBUS DI and connected push button

I could need some help with my modus DI/DO device. I got it to work with modbus 2.0 binding. All DI and DO contacts are connected to OH contacts or switch items. Works perfect. I get all the status changes.

But on some of the DI-ports I connected push buttons. At the moment the poll interval of my modbus config is 500ms. If I press and release the push button to fast, I cannot catch the signal. I think this is due the to high poll interval. But I think to lower it to 200ms will cause too much traffic and workload?

And idea to fix this.

Is your modbus device a plc? If it is then you could program somekind of delay that when you momentarily push a button it holds the “on” state for example one second. Or would latching relay mechanism do the job. One push of a button would turn on and second push off?

“it depends”. I’d say try it and see. Remember that with v2 modbus binding you don’t have to poll everything at the same rate, so only set up poller Things includng pushbuttons for faster polls.

You’re trying to fix a problem inherent in polled technology. If your modbus slave is just a simple i/o device, there are limitations. You might be able to apply a hardware solution - perhaps just a big capacitor across the pushbutton will give you some pulse stretching.