for standard A/B encoer (slow enought for normal DIs)

Edge on A (rising when B=0 or falling when B=1) changes UP

Edge on B (rising when A=0 or falling when A=1) changes DOWN

Sketch

NW1: UP

I_CH_A             FPN_CH_A      I_CH_B
------||-----------------|\|---------------|\|---------------------------|ADD|
                                                                        |
I_CH_A             FPN_CH_A      I_CH_B          |
------|\|-----------------| |---------------| |---------------

NW2: DOWN

I_CH_B             FPN_CH_B      I_CH_A
------||-----------------|\|---------------|\|---------------------------|SUB|
                                                                         |
I_CH_B             FPN_CH_B      I_CH_A          |
------|\|-----------------| |---------------| |---------------

NW3: Update previous value for edge detection - channel A
I_CH_A             FPN_CH_A
------||-----------------()

NW4: Update previous value for edge detection - channel B
I_CH_B             FPN_CH_B
------||-----------------()

When I have no HSC input available, I choose what I call an F/V (F to V) signal conditioner.  Converts frequency (pulses) to a voltage.  You basically get the speed of the knob in your specific situation.

You could take it to a pulse count -> voltage signal conditioner, but those are tougher to find except when you choose one of those signal conditioners that converts nearly everything to nearly everything else (highly configurable signal conditioners).

However, you could choose an Arduino (or similarly programmed) µController IoT based device that converts the pulses to analog and accept the signal as analog input to your ET200.

jasponp128

I have an analogue speed pot on a control cabinet we want to change to a digital encoder dial.

Trouble is no HSC counter available as its a Et200SP input module.

I have managed to get it to work- but had to make a clunky program 50ms pulse timers - see screenshot.

Surely there is a more elegant  way to do this?

jasponp128

I have managed to get it to work- but had to make a clunky program 50ms pulse timers - see screenshot.

The code seems fine. Except timers. Find attached a quadrature decoder for reference. Maybe it can be coded more brilliantly but I'm not LAD guy.

Please check if variables used for |P| and |N| are not used elsewhere and are STATIC or DB or M, NOT Temp!

              I_Input_1                                    Pulse
--------------|P|----------------------------------()
              FP_I_Input_1

in the above example FP_I_Input_1 must be STAT or DB or M and must not be written by any other part of the program.