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Author Topic: dspMC Device disarmed PID loops unexpectedly  (Read 19921 times)

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dspMC Device disarmed PID loops unexpectedly
« on: November 13, 2014, 02:01:09 PM »
Hi

I have run into a problem with my CNC upgrade project.

Everything seems to work fine, I can move the axes around, activate outputs, select tools and so forth but when I try to activate the spindle things go south.

When the spindle starts it doesn't take long before the dspMC stops and returns the following error; "dspMC Device disarmed PID loops unexpectedly"

I've struggled with the spindle quite a bit now. It's controlled by a Frenic 500G9S inverter. At first I tried to use the 0-10V analog signal to controll the RPM but then the dspMC stoped within seconds, with the same error. The faster I set the spindle RPM the faster the dspMC stopped. After a while I gave up and connected a potentiometer to the VFD instead to control the RPM. Now everything runs for a minute or so before the dspMC stops.

If i leave the spinlde off it seems to keep running without stopping.

Anyone got any idea on what could be going on?
Re: dspMC Device disarmed PID loops unexpectedly
« Reply #1 on: November 13, 2014, 02:19:04 PM »
Looks like the electrical noise from the spindle is causing the Disarm problem.  you will need to connect good earth ground to multiple places on the 0v wires, ie, make sure the signal ground on the VFD is earth grounded.  also the -ve of the power supply feeding DSPMC should be earth grounded.  in addition, multiple ground(return) terminals on J2 on dspmc should also be earth grounded.

you may also move the high power motors and spindle cables away from the DSPMC.

This is a very common problem with VFDs.

hope this helps.

Rufi
VSI






Re: dspMC Device disarmed PID loops unexpectedly
« Reply #2 on: November 14, 2014, 04:38:02 PM »
Well, I've figured out one thing. The Italians didn't really care much about electrical noise back in the 90's.
The high power lines to all spindles and motors are bundled together with the signal cables and no one of them are shielded!

Anyway, connecting ground to the J2 breakout board and that did solve the issue with the dspMC quitting on me. I've already made care so that all other signals are optically separated except the analog output controlling the RPM of the spindle.

But now I've encountered another problem (this CNC just don't want to cooperate!). The output voltage can only be set to about a third (~3V), if it's raised any higher the voltage drops under 1V and stays there until the output is lowered. Then it can be raised it again to 3V and it seems stable at 3V.

My guess would be that there is to much amperage flowing but how do I confirm this? And more importantly, how do I prevent it? Or am I wrong?

//Jonas
Re: dspMC Device disarmed PID loops unexpectedly
« Reply #3 on: November 14, 2014, 04:38:41 PM »
And thanks for the quick reply yesterday :)

//Jonas
Re: dspMC Device disarmed PID loops unexpectedly
« Reply #4 on: November 14, 2014, 10:33:36 PM »
>But now I've encountered another problem ....The output voltage can only be set to about  (~3V)

Where are you measuring the 3v?  Are u talking about vfd command input?  kind of lost on what problem you are talking about.

Rgds
Rufi
Re: dspMC Device disarmed PID loops unexpectedly
« Reply #5 on: November 15, 2014, 08:45:03 AM »
I'm trying to use one of the analog 0-10V outputs to control the VFD that powers the spindle. I'm measuring at the J2 breakout board over pin 19 and ground.