Internet PLC Forum

General => Technical support => Topic started by: GMG on September 27, 2004, 02:20:15 AM

Title: Low Frequency
Post by: GMG on September 27, 2004, 02:20:15 AM

What is the lowest possible frequency to measure with T100MD+. I am trying to make RPM meter to measure
low frequency from 0.5 Hz to 2 Hz and display the change in small stepps. I am using input # 3 and PMON 1 with
PULSEFREQUENCY(1).

Title: Re:Low Frequency
Post by: support on September 27, 2004, 12:45:28 PM

Since the PLC does not support floating point, you can use the PULSEPERIOD to measure the period in microseconds and then convert it to Hz. In that case you could use a fixed point number to represent your frequency. E.g. each unit represent 0.1Hz,  123 means 12.3 Hz.

  x10Hz = 1000000*10/(period in microsecond).