Hi, I was wondering what equipment I need to count pulses of a stepper motor, to make sure my cnc router is operating perfectly.
After reading some of the replies here I have to wonder what you are actually trying to accomplish as I was left with the impression you want to verify your CNC controllers code. As others have indicated if your goal is to mechanically verify operation you will need to do so with mechanical tools. Depending upon how far you want to go this would mean a collection of dial indicators, squares and straight edges.
I bring this up because getting a machine to run to mechanical spec is hard work and is never "perfect". Contrast this with software that needs to be as perfect as possible, software that loses counts or has off by one errors, is not acceptable. I say this as the result of working several years with a machine tool rebuilding mechanic, nothing is perfect but your work has to meet specs for that machine.
With home built machines, the builder is often limited by the tools he has available. For example if you don't have a good quality machinists squares you will have a hard time squaring up the machine. If the machine is too far out of square you will have a hard time getting your ratios right for linear movements, not to mention that everything will be slightly off as far as squareness goes.
So what I'm saying here is that you don't even worry about the CNC controls until you get the machine mechanically right. It will save you a lot of grief blaming the CNC controller when you have mechanical issues as the root problem.
Now on the flip side I can relate an instant when running a lathe in a loop helped us trace down an issue with a CNC controller loosing steps. In this case the controller was developing an error someplace in its code that resulted in a sub micron error in position that we could actually see after running the machine through many cycles. The thing here is that we would never had been able to measure that error on a sloppy axis in a reasonable time. Eventually we found that a relay inside a packaged spindle drive was causing a glitch that threw off the CNC controller a tiny bit each time the spindle was cycled. I say tiny because I don't actually know what was happening inside the controller, just that we had to run numerous cycles to even measure it with a dial indicator reading 2 microns per division. What you can take from this is that an error in the CNC controller was determined by making precise measurements on a well tuned mechanical axis. The issue was further narrowed down by running the same code with the spindle cycling eliminated. Note that at no time was there any counter used, in fact due to resolver feed back and servo drive it would have been hard to find a place to slap a counter.
So why the long reply? Simple to relate that your machine isn't perfect, there never has been such a mechanical contraption. The first limitation is your ability to measure and align. CNC controller code is an entirely different matter and there you need to rely upon the person coding the software.