Too fast for CLICK PLC?
Too fast for CLICK PLC?
(OP)
I have a simple timing application that the customer wants to solve with an Automation Direct CLICK PLC. I need to "measure" the time difference of two different discrete inputs. The expected time gap will be from 0 to 60ms. I know that resolution will be a function of scan time, since there is no high-speed timer module, so I'll be essentially counting scans between the two inputs. If I can get 10 counts in 60 ms, that will be enough resolution. It will be a very small program, so do you feel that I can rely on 6ms scan times or faster from this PLC? Or should I punt and suggest some other hardware?





RE: Too fast for CLICK PLC?
For you to sample correctly the scan time needs to be 1/2 of the input time. So you scan time needs to be 3msec to pick up the input correctly without missing it.
you need a high speed counter input.
RE: Too fast for CLICK PLC?
your looking for a change in 60msec? Just as long as the input changes at 2x in that time you ok. then the scan time needs to be 15msec to be safe. Or at the longest 25-30msec. Scan time is for continuous scan is based on the processor and how many instructions you execute. Each instruction eats up so much scan time to execute.
RE: Too fast for CLICK PLC?
RE: Too fast for CLICK PLC?