What is normal behavior for servo drive faults and reset

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ashesman
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What is normal behavior for servo drive faults and reset

Post by ashesman »

I was wondering what is normal practice for when servo drive faults occur and reset on E stop.

By default if a DYN4 drives go into fault, a fault situation is generated. This fault is not reset on cycling E stop. Instead the machine has to be shut down and power cycled. I can make the drives fault by pushing an axis as is movement without driving. Are servo drives normally reset by cycling E stop?

The spindle inverter is wired with a permanent power supply and separate high power supply switched through the same safety contactor as the servo drives. The inverter generates a fault state when the contactor is open as is the case when e stop pressed. This inverter fault persists when trying to exit fault state (cycling e stop) and prevents leaving fault state. I will need to add a bit of logic to delay checking of inverter OK state until after its contactor has been enabled and it can clear the fault.

Any thoughts or comments on fault and reset behavior?
martyscncgarage
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Re: What is normal behavior for servo drive faults and reset

Post by martyscncgarage »

Assuming Oak and DYN4
Did YOU Make up the signal cables or did you buy them from DMM already made? (MUCH preferred!)
How old are your DYN4 drives?

You cycle Estop, Oak will send a reset command to Dyn4 and should reset them them. It is pin 22 in the Oak signal cable. Pin out in the Oak Installation Appendix
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cncsnw
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Re: What is normal behavior for servo drive faults and reset

Post by cncsnw »

In my thankfully-limited experience with DMM drives, their "ARESET" input does not work to reset all faults. Some fault conditions will persist until power has been switched completely off, and left off for some minimum length of time.

If your question were "what is normal behavior for servo drive faults and reset, when Oak is used with well-engineered drives such as Yaskawa or Delta", then the answer would be simple:
1) When the drive is powered up and not in a fault condition, the drive pulls pin 19 of the Oak header down to near the 24V COM level.
2) When the drive is in a fault condition, it releases pin 19, which the Oak internally pulls up to +24V.
3) When pin 19 is open (high), the PLC program detects this and turns off its corresponding "DriveOk" memory bit (often in the range MEM16-MEM20)
4) If the PLC sees that an axis is installed and enabled, but is not okay (is in a fault condition), the PLC triggers and reports a servo drive fault.
5) Whenever emergency stop or (in many PLC programs) the VCP Reset button is pressed, the PLC program will activate (pull down) pin 22. In response, the servo drive is expected to reset its fault condition, so that it is again ready to run when emergency stop is released.

Since your question is implicitly "what is normal behavior for servo drive faults and reset, with DMM servo drives" the answer is more complicated.
1) When the green status LED on the front of the drive is lit, then the drive pulls down its "SRDY" signal (DMM pin 7, wired to Oak pin 19). The PLC program assumes this means the drive is okay.
1b) Unfortunately, the green LED is not only lit when the drive is okay. It is also lit in an over voltage fault condition, and is lit half the time in a "lost phase" fault condition (as the green LED blinks).

The blinking is not a big problem, since the PLC will latch the fault and not reset it until you press emergency stop or Reset. But the failure of the green LED and the SRDY signal to turn off in an over voltage fault is a problem. It means that you have a case where the drive is faulted and has stopped responding, but no fault is reported to the Centroid control.

Further, the function of the ARESET signal (DMM pin 14), even when it is correctly wired to Oak pin 22, is unclear. Perhaps it resets some faults, but it certainly does not reset all faults. If anyone reading this has figured out reliable guidelines for which are which, please share.
cncsnw
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Re: What is normal behavior for servo drive faults and reset

Post by cncsnw »

Regarding a spindle drive that reports an undervoltage fault while the emergency stop contactor is closed, you are correct: you need to add some logic to the PLC program.

Does your drive automatically clear its undervoltage fault condition after power is applied, or does it require a reset?

If the drive clears its fault condition automatically when power is applied, then you just need to add a timer, active whenever NoFaultOut is on, and use expiration of that timer as a condition for reporting a spindle fault. This can replace the "Initialize_T" timer condition in the typical PLC logic.
ashesman
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Re: What is normal behavior for servo drive faults and reset

Post by ashesman »

Thanks for the detailed answers. I will go through and check all the signals are wired correctly and doing what they should.

I am using the pre made DMM cables. The DYN4s have new firmware made especially for me less than a month ago so should be latest spec.
martyscncgarage
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Re: What is normal behavior for servo drive faults and reset

Post by martyscncgarage »

ashesman wrote: Wed Jun 02, 2021 3:20 pm Thanks for the detailed answers. I will go through and check all the signals are wired correctly and doing what they should.

I am using the pre made DMM cables. The DYN4s have new firmware made especially for me less than a month ago so should be latest spec.
If you continue to have reset problems, consult with DMM.
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
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ashesman
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Re: What is normal behavior for servo drive faults and reset

Post by ashesman »

So, I confirmed for sure today that the Oak is not resetting the DMM drives correctly today. I emailed DMM and they said:
When the drive faults, it sends alarm signal to the OAK and OAK throws drive fault error and stops everything and also Disables the drive. When you cycle the ESTOP in the OAK, the OAK will send RESET signal to the drive which will reset the drive and clear any faults in the drive.

Power cycle will also reset any alarms in the drive but this should not be necessary since OAK does this using an input into the drive.
Today after running the self test function I slowly started increasing my maximum speeds from the conservative values I had used. At the full speed I want to run, testing with G0 X-150, G0 X150, the drive faults with "Lost Phase". Putting aside why the drive faulted, once I cycled E-Stop the fault was not reset.

I guess I will pull the Oak to DMM cables apart tomorrow and see how they are wired. I asked DMM for a cable schematic but haven't heard back yet. I think Marty mentioned in one of his videos there was an early cable with reset problems? Maybe I have one of those? I bought it late December last year.
martyscncgarage
Posts: 8462
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Location: Mesa, AZ

Re: What is normal behavior for servo drive faults and reset

Post by martyscncgarage »

ashesman wrote: Sat Jun 05, 2021 1:24 am So, I confirmed for sure today that the Oak is not resetting the DMM drives correctly today. I emailed DMM and they said:
When the drive faults, it sends alarm signal to the OAK and OAK throws drive fault error and stops everything and also Disables the drive. When you cycle the ESTOP in the OAK, the OAK will send RESET signal to the drive which will reset the drive and clear any faults in the drive.

Power cycle will also reset any alarms in the drive but this should not be necessary since OAK does this using an input into the drive.
Today after running the self test function I slowly started increasing my maximum speeds from the conservative values I had used. At the full speed I want to run, testing with G0 X-150, G0 X150, the drive faults with "Lost Phase". Putting aside why the drive faulted, once I cycled E-Stop the fault was not reset.

I guess I will pull the Oak to DMM cables apart tomorrow and see how they are wired. I asked DMM for a cable schematic but haven't heard back yet. I think Marty mentioned in one of his videos there was an early cable with reset problems? Maybe I have one of those? I bought it late December last year.
If you bought the cable late December of 2020, it should not have any wiring issues.
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
Mesa, AZ
slodat
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Re: What is normal behavior for servo drive faults and reset

Post by slodat »

On my DYN4 systems I have a separate breaker for drive logic power. I then cycle that breaker to reset a drive fault that won’t reset as described above.
ashesman
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Re: What is normal behavior for servo drive faults and reset

Post by ashesman »

slodat wrote: Sat Jun 05, 2021 12:15 pm On my DYN4 systems I have a separate breaker for drive logic power. I then cycle that breaker to reset a drive fault that won’t reset as described above.
I hope its not the case that some faults cant be reset. It seems pointless even having a separate logic power if you have to cycle it to reset a fault! Cycling logic power would mean needing to rehome the machine as you have interrupted the encoder signal which would be a nuisance. Although less of a nuisance than a full power off and startup I guess!
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