Hi @Tom@Pton (Customer)​,

This is easily done with the Click PLC.

This is available on all of the Ethernet units that have DC inputs. There are seven (7) different modes of operation for the high-speed counter available so adaption to your automation solution is easy. The input can count Up, Down, Up/Down, Pulse/Direction, or Quadrature (with Z). The maximum speed on the high-speed counter inputs is 100 kHz. That is 100,000 pulses per second.

https://accautomation.ca/click-plc-high-speed-counting-part-1/

https://accautomation.ca/click-plc-high-speed-counting-part-2/

Depending on the model of C-More (EA9) you could add the Click to this in the same system.

Regards,

Garry

https://accautomation.ca/series/click-plc/

Absolute encoder was my thoughts. Single turn. Rotary.

I've managed to get to the link ADC gave, then watched a few more from other sources. Good info.

Of 6 possible positions in the 180 degree of travel, I only need 3, at the moment. Speed is not an issue. Maybe a minimum of 5 seconds between adjacent positions.

(Now thinking a linear will be better) More research on my part.

Thanks again

If you are looking to get a cheap PLC to add an encoder to your existing system, I think Click is a good way to go if you want an incremental encoder. However, if you were looking at an absolute encoder then a P1000 is much better. There is a built-in instruction for getting a position value from any gray code or binary ABS encoder and the ease of use on the absolute encoder types is easily worth the extra price over a Click for this specific purpose IMO.

 You could use a 360 count encoder for your application since you only want to move 180 degrees. A 360 encoder would make each degree be 1 count, so it is easy to think of and do the math in your head. Or if you need more resolution, a 720 count encoder would give you a count every half degree. You can then use a "scale" instruction and scale the position tag with 720 counts maximum into a new tag with a 360 count max, and use floating-point data type. This would allow you to still have everything go from 0 to 360 degrees but would increment every half-degree instead. You can do this with higher count encoders as well, but the maximum count Automation Direct sells is a 4096 count ABS encoder, and personally, I just prefer using count values divisible by my end target (like 360 or 720).

If you do go linear position sensor, most of those use an analog output of one sort of another. These can be thought of as "absolute" positioning in that they will retain a value on startup depending on where they are and will not start at "0" like an incremental encoder would. You just have to scale the analog input counts to a unit of measure that makes sense for you, which any of the PLCs will do. You would most likely want a Click for this type of measurement as well, since you can buy a Click with analog IO already in it, so it is cheaper than a P1k by a good margin.