Hello Vital System Team
I have noticed a little issue with Mach4, Hicon7766 and backlash compensation. It is not adding backlash comp to .0001inch moves while jogging, Not sure if it is a Mach4, but assume it is a hicon issue because that is where the backlash is entered in the system. .001 and .01inch moves backlash works on most of the time every now and again it does not apply backlash
Mach4 version 2.0.3233 and the latest test version both have been used
Hicon 7766, FW:3.46 FPGA:7E7C
5mm Per revolution ballscrews
10000PPR Servo motors using encoder feedback to the Hicon Closed Loop from motor encoder direct drive to the screw
50800 steps per inch in the motor setup units
velocity set at 175
acceleration 50
backlash entered was .0009 Hicon calculated tp .00088583
This was tested with MDI, MPG pendant plugged into Hicon MPG port, a Modbus MPG pendant that is being worked on, and with incremental jog controls From the Mach4 screen.
First Thing that was noted is backlash comp will not be added to .0001 moves using jog controls or MDI. The Machine is capable of the move and it does when going one direction. as soon as you reverse direction at .0001 increments the DRO on the mach screen will show the axis moving the backlash amount before it shows movement on the indicator. If the increments are set to .001 it works fine most of the time.
Second thing that was noted is testing backlash on a machine using a part program and not a jog move. The program moves to point where the indicator was zeroed, off the block past zero by a inch then back to the Zero point. if the indicator shows that it is loaded then comp is added by the loaded amount, If the indicator shows that it is light then the comp is too much and need to be reduced.
here is the program that is used for Y axis.
G01 X0.0000 Y-1.0000 F10
G01 X0.0000 Y0.0000 F10 (Part Zero)
M01
G01 X0.5000 Y0.0000 F10
G01 X0.5000 Y1.0000 F40
G01 X0.5000 Y 0.0000 F40
G01 X0.0000 Y0.0000 F10 (return to Part Zero)
M01
M30
The program is one that is run several times before it is determined the the backlash comp Value good. The reason I do this is if you over comp the machine by .00005 it will cause the Zero to walk. When testing our machines at work we do it at least 3 times knowing that the indicator we use is only accurate to .0001 we allow .0001 of error. but If we see the indicator start moving a little when we go back to zero each time we will run it 10 time in a row to look for over comp.
I was doing this and noticed on the 9th run of the program that compensation was not applies at all. Opened up the diagnostics screen and started watch the encoder counts for first touch of zero count and second touch of zero count.
when the backlash is being compensated for the first touch of Zero was 238386, Return to Zero was 238343
when backlash comp was skipped first touch of zero was 238386, return to zero was 238386. This was also reflected on the indicator showing about .0009 loaded
ran the program 21 times and 5 time it did not apply the backlash compensation
commanded position for each run for first touch of zero and return to zero was 238364 if backlash move was applied or if it was skipped.
Ran the motion planner from the diagnostics page it look like it just shows the encoder position or step generator of what ever axis you select but does not show commanded to compare it to.
Is there any thing I can provide to help with this issue or help diagnose the issue I seem to be having.
I would swear the not comping backlash for a .0001 jog move worked several plugins ago, But i can not be for sure will the early 2016 plugins, FW and FPGA still work with the latest revision of Mach4? I would go back and try them out.
Thank you
Robert