I have a PCI-6251M Series and SC-2345 with SCC-DI01 installed. The input signal is a TTL pulse train from an encoder (360 pulses/revolution). I am trying to measure the frequency of this signal and convert it into an RPM measurement. All the examples I have found regarding frequency measurement use the built in counter which does not allow me to choose the input signal (di0) from the SCC-DI01 (must be a physcial channel...) I have connected the TTL input into CTR0, and using some of the examples I could get a frequency reading. Why can't I do the same using the SCC-DI01? Because the SCC-DI01 is optically isolated I feel more comfortable usign it than having inputs wired directly to the 6251 CTR input.
Using DAQ assistant, I have the data from SCC-DI01 di0 (boolean) signal manipulated (DDT) into a binary stream (0 and 1 output). Using the Signal Timing and Measurement function results in an "inf" frequency reading.
I'm sure I'm missing something very trivial, but thus far have not been able to find a solution. NI support helped getting the frequency measurement through the counterCTR0, but not through the SCC-DI01. I'm using LabView 7.1 (have not installed 8.2 on new PC yet), and relatively new to LabView. Thanks in advance for any help.
