PDMX 126 with AM822 drivers and relays.

[m_c]

I'm assuming disabling the outputs will also cut power to the stepper drives?
If it doesn't, the drives will remain in fault until the power is disabled.

VFD wise, cutting power is fine, provided the power is cut cleanly, however the spindle could still continue to run for a few seconds afterwards depending on how quickly the internal capacitors discharge to the point the VFD faults out due to under voltage. The easiest option is to have the forward/reverse/run disconnect instantly, which they should do if they're wired to PMDX outputs, but also have the input power cut at the same time. That way the VFD should have things stopped, before it runs out of power.

From a practical point, there should be no noticeable difference between using a common +5V or common 0V/Gnd.
The main thing is to use suitable wiring to eliminate/minimise noise, which could cause lost/gained steps.

[dachopper]

When you say "cut power" to the drives, I was going to wire the motor power supply direct to the stepper motors meaning only the step/dir inputs from the PDMX would be cut. The main stepper motor power would still be connected. Is there a problem leaving the drivers in fault mode? or are people removing the power to stepper motors also?

[JAZZCNC]

Think you should knock up schematic which will help you and us understand better exactly what you have in mind.
Like MC says if you don't clear the fault the PMDX will never come out of fault so you'll be stuck in a loop. This means you'll need to Kill power to the drives or use the Enable/reset option on the drives.but this may not suit your plans or the PMDX but without seeing schematic it's not so easy to see what your intending regards E-stop etc.

[dachopper]

I read in the PDMX manual, if the charge pump signal is disabled, then it will disable the PMDX-126 and all motor drivers. If the drivers are disabled, then they cannot be in fault mode right?

The UCCNC software, can be set to de-activate the charge pump signal, whenever the software is in reset - ( which occurs when passed an E-stop or Fault signal for example )

So in summary Am882 Drivers detect fault. PDMX detects the 882 fault signal and passes to UCCNC. UCCNC goes into reset, which disables charge pump. PDMX now disabled ( powered down ) as charge pump off.

Click on UCCNC reset button now powers up PDMX, which powers up motors ( fault signal effectively reset ), Continue job.

Am I missing something regarding the fault loop? or does this sound like it will work?

Attached, schematic of rough config
Attachment 21408

[Clive S]

Attached, schematic of rough config
Attachment 21408

This is showing an invalid attachment at my end.

[dachopper]

try again

[JAZZCNC]

I read in the PDMX manual, if the charge pump signal is disabled, then it will disable the PMDX-126 and all motor drivers. If the drivers are disabled, then they cannot be in fault mode, right?


Am I missing something regarding the fault loop? or does this sound like it will work?

Yes, you are missing the fact the Drives will still be OUTPUT a fault signal unless the fault is cleared inside the drives. The PMDX only disables its OWN OUTPUTS it cannot control the Drives OUTPUTS and because you're watching these OUTPUTS with the PMDX INPUTS then the fault signal going to the PMDX will Never be cleared.

Also, think your misunderstanding the Charge Pump. The function of the Charge pump is to disable the PMDX outputs if the connection to the PC is lost. Shouldn't be used for E-stop or to control drives etc.

The drives could be reset using the Enable signal but not a good solution IMO because it's relying on software.

[dachopper]

I see, I just read this from 882 manual "Reset the drive by repowering it to make it function properly after removing above problems" so, if I have one of the pdmx relays controlling the driver voltage, so it cuts driver voltage on fault, this should accomplish the job, or I can manually cycle 882 drive power to clear ?

If I'm using the relay, should it be cutting power on the DC side, or AC side of my power supply?

Nick.

[m_c]

I see, I just read this from 882 manual "Reset the drive by repowering it to make it function properly after removing above problems" so, if I have one of the pdmx relays controlling the driver voltage, so it cuts driver voltage on fault, this should accomplish the job, or I can manually cycle 882 drive power to clear ?

If I'm using the relay, should it be cutting power on the DC side, or AC side of my power supply?

Nick.

Always cut the ac side. Cutting the dc side risks blowing up the drives.