moving average vs. low pass filter

Hi,

I'm somewhat weak on filtering theory.

We're having a discussion in the office about using a moving average filter versus a low pass filter in RSLogix for an I/O input measuring pH.

If I run tests in the PLC I can see some of the differences in the results, but I don't know where/how to start when it comes to the language/math of comparing the two methods.

I also don't understand where one would use moving averages or low/high/band pass filters in an industrial application.

Thank you,
Chris

Moving average is a low pass filter, it is FIR (finite impulse response). You can designe either FIR or IIR low pass filters.
Moving average filter can suite your needs, but that depends on actual application. Usually, moving average filter doesn't have very steep characteristic, which can be considered as a disadvantage.
Usually you can get better frequency response (steeper pass band curve) with IIR, but again, that depends on the actual application and type of filter. There are many windowing methods for designing FIR filters with very good responses. Your question is just too general. I suggest you to do a little research on this topic. You can found a lot on wikipedia, for example.

Cheers