I am using a Micrologix 1400 high speed counter to monitor an encoder on a rotating shaft. I have an STI running every 2ms which takes the encoder accumulated count, subtracts the previous count and then calculates the shaft speed. My problem is that at a constant shaft speed the difference between current and previous counts on successive scans fluctuates by as much as 20%.
I guess that this relates to the timing of the HSC count update within the PLC scan.
Does anyone know of a method to force an immediate update of the HSC accumulated value ?
I guess that this relates to the timing of the HSC count update within the PLC scan.
Does anyone know of a method to force an immediate update of the HSC accumulated value ?