Internet PLC Forum

Ok, I understand your explanation. Our application requieres the two HSC channels to be exposed to that frequency range. By now we can reduce the pulse frequency, and we can work out of the problematic frequency range.

Thanks,
Juan C Peris

I have running problems when the PLC gets pulse data from high speed counters inputs or from pulse measurement inputs. The PLC slows or even stops the ladder-logic program. When input pulses stop, then execution continues normally. And this problem is only at pulse frequencies between 450 Hz and 1250 Hz, aproximately. Outside this range PLC works fine, even with frequencies greater than 1250 Hz.

I am using a FMD88-10 PLC and I detected the problem when I configured two high speed counters inputs to get pulses from two rotatory encoders with 2000 pulses per revolution. Rotatory speeds are very low, between 15-100rpm. Then I tested to read pulses using pulse measurement inputs, and I got the same problem.

We have looked for noise problems, but is all ok. We have also made tests with ladder-logic programs wiht only the minimum lines to configure the high speed counters and/or pulse measurement.

Thanks,
Juan C Peris