Hi,

I am using a drive for closed loop speed control. The drive monitors the frequency from an encoder, and adjusts the output to a motor so that motor speed is controlled at setpoint.

As a way to test and document the performance of this drive system, I would like to find a data recording instrument that would be able to log/record the frequency of the encoder signal over a period of time. Currently, I have a 240 PPR encoder and my motor speed range is 0-1750 RPM, so my frequency range is 0-7000 Hz. Ideally, I would like to be able to record frequencies as accurately as possible at 0.1 second intervals.

If anyone could recommend an instrument that would have this capability, I would greatly appreciate it.

Thanks in advance,
Paul

 

Most paperless recorders can do 10 updates per second; Honeywell, Yokogawa, Eurotherm, ABB.

Recorders take generic DC signals, like 0-1Vdc or 0-5Vdc. So you'd need a frequency to DC converter. If the frequency signal voltage is in the range of 25mV to 2.5V Dc, then something like this:
http://api-usa.com/pdf/api/api7580g.pdf

accuracy: If the max frequency is 7000 Hz, not 1750 Hz (different in subject line vs the msg body); the 0-8000Hz range over 10Vdc is a resolution of 1.25mV per Hz resolution. That module's accuracy is 0.2% of span accuracy, or 20mV, which is 16 times more than a resolved 1 Hz. But Google is your friend, there are many freq-to-DC converters to choose from.

 

Instead of changing frequency to analog Voltage there must be a way of reading the output of a frequency meter directly and recording it into a file.

I'm sure a lot of bench top instruments have a digital output.