Programming Help

I must have not put enough information into my first question. Like I said before Im using and old 1747-l20c plc. my encoder will be hooked up to the internal high speed counter. The problem that I'm having is in the rslogix program the high speed counter is an actual counter. This throws me a curve ball because I need to subtract from the amount of counters that the counter is counting. I need to do this because im using a VFD with ramp to stop . So lets say that when the counts get to 2000 is shuts off an output turning the VFD off and lets the VFD ramp to stop

heckpalm76 said:

I need to subtract from the amount of counters that the counter is counting.

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HUH??? That really confused me...

You can acced the value in the HSC just like any other counter. You can (for example) MOV HSC:0.ACC to N7:0 and then do any sort of math on N7:0 you want. So you can take your starting point and move that into an N7:0 and then evey scan, move the value into N7:1. when N7:1 - N7:0 > 2000, toggle your output.

Hope that helps.

Greg

Thanks for you help Gosenbach that is exactly what is was looking for

No problem.

also keep in mind that you are going to want to reset the HSC every once in a while. In you example, after you turn off your VFD, reset the HSC. It gets difficult to manage if your values start getting extremely large over time.