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GeoBrick LV amp fault when using step/direction output


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We have two GeoBrick LVs where we are using one channel on each for step/direction output.


On each of these, when I command an output on the channel configured for step/direction, I get amplifier faults on some other channels of the controller that are using the GeoBrick amplifiers.



- Channel 6 is configured for step/direction

- #6o10

- Channel 6 moves as expected

- Amp fault status immediately reports 6C error code

- #6k

- Amp fault now also reports 1C and 8C error codes, in addition to 6C

- Motors on channels 1 and 8 cannot be moved. PeWinPro reports Amplifier Fault.

- Clear amplifier faults (enabling startup PLC)

- Motors on channels 1 and 8 can now be moved normally.


The configuration for Channel 6 for step/direction is as follows:

- PFM enabled on encoder connector (5V->Pin 8)

- I600=1 (enable channel)

- I601=0 (disable commutation)

- I602=$7810C (use output C)

- I624=$100401 (amp fault ignored)

- I669=200 (limit output frequency to ~2 kHz)

- I7100=1473

- I7103=1778 (clock divider to allow 2 kHz PFM)

- I7104=20 (to get desired pulse width)

- I7126=3 (PFM on output C)


A few questions:

- Should Bit 16 of I624 be set to 1? We are not using the amp enable output in this application. Or does the setting of this bit not matter?

- Does Bit 10 setting in I624 matter?

- Are there any settings on the other channels that should change?

- Does the value in I7104 have any bearing on the other amp channels?

- Is there anything else that I've missed?

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I think that I7104=20 is the problem. Unfortunately, in addition to setting the PFM pulse width, it sets PWM deadtime. The setting would have to work with other channels on the IC that use PWM control.


What about the pulse and direction output on the Handwheel port? Is that already used?

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Thanks for the response. The I7104 setting is one of the ones I was going to experiment with. I will return it to its original value and see if the pulse width is sufficient for the external motor drive.


We have a repackaged version of the GeoBrick LV where we do not have the handwheel port available externally.

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Some followup on our findings:


- changing I7104 to 3 (our default setting) did not change the amplifier fault behaviour

- changing the startup PLC to change Channel 6 to 'no amplifier' (issue COMMAND"wx$78114, $F9CCFE", do not issue COMMAND"wx$78114, $F94DFE") in our amp config startup PLC resolve the amp fault problem on Channel 6, but the faults remain on the other channel.


Some other notes:


- amp faults are not isolated to the Channel 5-8 range, so it appears to not be related specifically to the ASIC

- we have an expansion board in this GeoBrick-LV with absolute encoders (BiSS-C) configured. The channel we are using for step/direction output is not set up for an absolute encoder input. We are using absolute encoders on encoder inputs 4 and 7.

- we see the following amp faults on the status display: 3C5C7C8C. These appear only after channel 6 output is killed.

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You said that your default setting for I7104 is 3...do you have another configuration that generally works on these systems? If so, would you be able to send both it and the current configuration to support at deltatau dot com so that we could compare the two to look for anything that may be relevant?


If not, the default value is normally 15.

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  • 7 months later...

Hi Wayne


If you think it is unrelated to the servo IC then we found that newer versions of the GBLV amp firmware were more prone to nC faults than previously. Careful setting of Ixx69 ( as small as practical) mitigated against these faults on respective axes.


This problem was not seen in early GBLV set up files when the ECT threw away everal significant bits of integrated torque demand, but is more apparent in the newer set up's where all the bits are read.


We now normally use 10,000 step per rev ( Ix71=6400) so only need Ix69 of 5 or 10. We only need to increase Ixx69 when we need to go to the high resolution microstepping ( ix71=64000 giving 100000 step per rev from 1.8° motor).


Having low Ixx30 and relatively high Ixx32 also helps.

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  • 11 months later...

Hi All

we are having the exact same problem as reported by WLewis. Unable to utilize pulse and direction without causing amplifier fault errors. This happens even with bus power turned off. Tried all the suggestions in previous replies with no effect. Unable to mix pulse and direction channels with stepping motor channels due to these errors.


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