325 Limit Error? <resolved>

[cncsnw]

The 327 Fault message, by itself, is generally a sign of sloppy PLC programming.

The PLC has detected a Fault condition and has set the SV_STOP system variable, which causes the job to be cancelled with the "327" message, but the PLC has neglected to trigger display of an appropriate additional message to explain the Fault condition.

The block in the PLC program that is likely to have set SV_STOP reads:

Code: Select all

IF !EStopOk || PLCFault_M || SV_STALL_ERROR || SpindleFault_M || SkinResetSet_M ||
   LubeFault_M || AxisFault_M || ProbeFault_M || OtherFault_M || DoorShutDownStop_M
   THEN SET SV_STOP

With some homework and some effort, you could locate each of those tokens (except for SV_STALL_ERROR) in the PLC program; then use the Alt-i display to see which of them is set when your 327 fault occurs. For example:

Code: Select all

DoorShutDownStop_M			  	IS MEM25
;...
;--DoorShutdown Mode
;IF in Shutdown mode and door is open, STOP and send error
IF (DoorInterlockShutdown_M && !SafetyDoorSwitchClosed_I)
	THEN SET DoorShutDownStop_M, ErrorMsg_W = WAITING_FOR_DOOR_CLOSED

So, if MEM25 turns green on the Alt-i display when your fault occurs, then you know the problem is with the door interlock logic.

In your case, since Parameter 985 = 0, we can probably assume that DoorInterlockShutdown_M is false, so it is unlikely that the door interlock logic is the issue. But you could follow similar paths to check out PLCFault_M, SpindleFault_M, SkinResetSet_M, LubeFault_M, etc..

You could also use the Source view in PLC Detective to see what tokens in the catch-all SV_STOP line are highlighted when your 327 fault occurs.

[RGSparber]

Ah, so the 327 fault is not from the CNC12 program but from the PLC inside the Acorn. That helps narrow my search for the root cause.

I have only seen this fault when the spindle motor is running. I unbolted the VFD from the wall and moved it as far away from the Acorn and PC as possible. None of its cables are now within 2 feet of any other cables. I still got the fault. I ran at half RPMs and still got the fault.

I changed the probe input (IN 6) from Probe Tripped to blank and again got the fault. I then restored IN 6 to Probe Tripped.

I took my bundle of limit switch wires and moved it away from all other wires. Still got the fault.

The time it takes to hit this fault is random and between 8 and 20 minutes.

Unless there are other suggestions, I plan to disconnect my Home wires from the Acorn to see if they are carrying the noise in.

Thanks to all for your suggestions.

Rick

[Gary Campbell]

IS your VFD cable properly grounded?

[RGSparber]

Gary,

I believe so: https://rick.sparber.org/VFD_Noise_Reduction.pdf

At the present time, Centroid hardware does not control my VFD although paths are present. They are optically isolated.

Rick

[martyscncgarage]

Did you change from Homelimit to homeok?

[RGSparber]

Yes. No joy.

Rick

[martyscncgarage]

Rick, earlier you said the spindle was off and you still got the fault. Was the VFD on or off? Is it physically connected to Acorn in any way?

Picture of your control cabinet please?

[RGSparber]

I meant to say that I have only seen the fault when the spindle was on.

Details of my hardware are at https://rick.sparber.org/ma.html#CNC.

The VFD is optically connected to the breakout board which connects to the parallel port.

I just disconnected my home sensors and turned off those inputs in Acorn. I also disconnected 24v and Com used by the sensor. powered cycled. After coming back up, I got the fault after 3 minutes. Repeated the test now. I got the fault at 24 minutes. This implies I have zero noise margin somewhere.

Rick

[martyscncgarage]

Rick,
Could you please just post a current picture of your control cabinet showing Acorn here.

So you disconnected your home sensors and the fault still occurred? What is still connected to the inputs and outputs of Acorn?
Could you please also post a current fresh report.
What kind of drives are you using? Connected to DB25 (5V logic drives) or the Acorn header terminals, 24V logic drives.

Marty

[Gary Campbell]

Have you tried a line reactor or EMI filter on the power input side of the VFD?