Spindle Scaling with 7i77 not working

Hi Guys,

I am retrofitting a Bridgeport mill using a 7i77 board and a VFD from Hitachi (WJ200), and having some problems. If I type in M3 S2 for example, the 7i77 will output 2 volts and the spindle will spin at 20% RPM. If I enter anything above 10 as the S value, the spindle spins at maximum RPM.

I have tried every permutation that I can think of in PNCCONF to scale that so that I can enter an RPM value in the MDI screen instead of having to enter a voltage, but to no avail.

Does anyone know what I am missing? Thanks,

Mr. Technical

Typically you need to set three parameters to get the scaling and bounding right
assuming you are using analog out 5 and max spindle RPM is 6000, something like this:

setp hm2_5i25.0.7i77.0.1.analogout5-maxlim 6000
setp hm2_5i25.0.7i77.0.1.analogout5-minlim 0
setp hm2_5i25.0.7i77.0.1.analogout5-scalemax 6000

If pncconf doesn't get this right, you will probably have to edit the hal and or ini files

If you have a bipolar spindle speed control (-10V to +10V)
you probably want:

setp hm2_5i25.0.7i77.0.1.analogout5-maxlim 6000
setp hm2_5i25.0.7i77.0.1.analogout5-minlim -6000
setp hm2_5i25.0.7i77.0.1.analogout5-scalemax 6000

Thanks for the help. I ended up figuring out that I needed the output_scale at 3930.0, The output_min_limit at 10.0, and the output_max_limit at 3930.0 in the .ini file, which made the spindle operate correctly in forward, but not in reverse. It turns out that the WJ 200 VFD that I'm using cannot take negative analog input. While troubleshooting, I somehow caused the Mesa board to stop outputting 0 to 10 VDC on analog enable 5. So I'm back to zero spindle movement in either direction.

So I have two questions:
Is there a way to test that the board's output is not damaged in some way?

If it isn't damaged, is there a way to have the voltage for reverse only come out as positive? Thanks in advance for your help,

Mr. Technical

After further digging, it looks like I have damaged analog5. I switched to analog4 and am seeing voltage for both directions. Forward is positive, and reverse is negative. So at this point, I still need to know how to make the reverse direction voltage positive as well.

Instead of using the pin "motion.spindle-speed-out" (or motion.spindle-speed-out-rps) for your speed reference command, use the pin "motion.spindle-speed-out-abs) (or motion.spindle-speed-out-rps-abs). Then the command will always be positive.

Todd, that worked like a charm. Thanks very much!