View Full Version : DPC spikes stalling stepper motors

Mad Professor
22-10-2011, 05:33 PM
Good day all.

I have not long ago upgraded my cnc pc, but ever since I am having nothing but problems with the stepper motors stalling.

Here are the details for my current cnc pc:
Intel Pentium 4 (640 Prescott) @ 3.2Ghz.
FoxConn NF4SLI7AA-8KRS2.
2GB (2x1GB) DDR2.
nVidia nForce 210.
60GB IDE Seagate.
Moschip MCS9865IV-AA Dual LPT Card.
Windows 7 Home Premium 32Bit SP1.

As per the title I think that my problem is related to spikes in the DPC (Deferred Procedure Call) (http://en.wikipedia.org/wiki/Deferred_Procedure_Call).

I have run the Mach3 driver test as this shows no problems or spikes.

But when I have Mach3 running and run any of the axis I will get ramdom stalls, and if I run more then one axis at a time they will stall at the same time.

I downloaded a DPC Latency Checker (http://www.thesycon.de/eng/latency_check.shtml), and I could see that eveytime that the motors stall, there was a spike in the DPC.

This cnc computer, has had a clean install of Windows 7 Home Premium 32Bit SP1, and the only other programs that are installed are Mach3, and CamBam.

Can anyone here give any advice?

Thanks for your time.

Best Regards.

22-10-2011, 05:37 PM
Can you try windows XP?

Also what kernel frequency?

Mad Professor
23-10-2011, 10:21 AM
I am using 25Khz kernel, but have tried a few other speeds but get the same.

The old system that I have just upgraded from was also running Windows 7 Home Premium 32Bit SP1, I did not have any motor stalling problem, just that the system was very slow at booting and loading programs.

I can try installing windows xp on a spare hard drive if I can find my old windows xp install cd.

I don't think this problem is a OS / Software related problem, I think it's a hardware issue with the motherboard it's self.

But anything is worth a try.

Best Regards.