[Codythecreator]

Hey guys. So I’ve been using mach 4 for about a year now, and it’s been doing fine. But one thing I want to fix is not having an accurate way to determine rpm. I installed a Hall effect sensor back when I started using Mach, but could never get a “True RPM” DRO displayed on the screen.

What are the steps one would have to do to achieve this ? Any help would be awesome. Thanks

[maxspongebob]

Show us a screen capture of your M4 system. Both the mill and lathe screens have a RPM DRO right there. Are you not seeing the indicator or is it showing incorrect data?

[joeavaerage]

Hi,
what motion control are you using?.

It all starts there. This is how the ESS works: it resets a counter when it detects a index pulse, and then starts counting at 4Mhz, until another index pulse is detected. It latches the count into a register, resets the counter and
starts counting again. Thus the register contains the number of counts between two index pulses. The ESS reports to Mach about every 25ms (default) including the current value of the register.

Mach does the calculation to get the rpm from that value and uses that to populate the Spindle Speed DRO..

There are several things that can go wrong. For instance if the motion controller 'cannot see the index pulse' , say something like heavy low pass filtering on the breakout board inputs or insufficient index pulse width.


There is another possibility: Mach can only display the acutal current rpm if its being fed with data. What happens if its not? Most installations don't have an index pulse generator so the motion controller will
NEVER feed Mach with the required data. In that case Mach will populate the DRO with the commanded speed, it is after all the best estimate its got...so it uses it.

May I suggest check the setting within Mach such that it shows the actual spindle speed. If its not getting data it will probably display zero, but at least it will be displaying the result of its calculation.
The second thing is to ensure that your motion board is set up to count index pulse, this is after all how it works.

Craig