PDMX 126 with AM822 drivers and relays.

[m_c]

I've just looked at the PMDX-126 manual.
The fault input should be left floating (aka unconnected) so everything gets enabled. To trigger the fault input/disable outputs, it has to be connected to 0V/Gnd.
For that to work with your drives, they need to be left in the default alarm output (active on alarm i.e. the + & - get connected on alarm), and then wired in parallel to the Fault input (all ALM+ to Fault input, and all ALM- to 0V/Gnd).

Regarding daisy chaining the Pul/Dir, I would personally do that at the BOB end, and use twisted pair/shielded wiring to minimise the risk of interference. The Enable signal is not as sensitive to noise, so I wouldn't worry about simply daisy chaining the Enable wiring across all the drives, if that was easier for wiring.

From what I understand from the manual, the Fault input once pulled low, disables everything, including the E-stop signal to the PC. The Error input doesn't disable anything, but triggers the E-stop input to the PC for 1 second, so is reliant on the PC disabling things.
The benefit of using the Error input, is if the drives allow re-enabling after a fault without needing their power supply cycled (i.e. turned off until the drives fully power down, and turned back on again), then resetting the E-stop via Mach and re-activating the drive enable signals should mean everything powers up again without the need for a power cycle. I know EM drives have the option to re-enable simply by disabling/enabling the enable input without a power cycle, but it has to be set via software.
The disadvantage being it is reliant on the PC handling the E-Srop.

[dachopper]

Ok - So I'm going to connect all ALM+ in Parallel to the Fault pin, and then all ALM- in Parallel to the GND pin next to Fault.

By my reading of the manual - the ENA + and - , is in the Enabled state by default as long as it is disconnected. ( Ie - I'm going to leave these pins not connected to anything = drive enabled )

For the Fault signal, my understanding is that Fault signal functions the same as the E-stop signal once it is active - as you mentioned. In that PDMX will disable all of it's own outputs, ( servo drivers, Relays, as well as signal to PC on PIN10 that the e-stop has been tripped). That then halts the operation on the PC and places my UCCNC software in reset active mode - which turns off the watchdog timer, which in turn backs up the PDMX in getting it to turn off outputs in the case the PDMX internal E-stop circuit fails to turn outputs off. ( In this state the AM882 drive signals should be unpowered - including the ALM+ and _ , and the PDMX has returned to Off due to watchdog timer not active? )

I then click on the software reset, which should effectively turn on the PDMX when watchdog becomes active again. Then I Home the axis to get rid of missed steps, turn on the spindle / coolant, and Run from a few lines before the fault freeze. - That's my plan. I was wanting to run the spindle power through the PDMX larger relay so that the spindle turns off, but I don't know of that's the right thing to do as it will cycle power to the inverter when the spindle is a full speed. - Maybe there is a better way like an e-stop that I can wire into the VFD. I did want to use the smaller PDMX relay to drive my spindle water pump, and also the dust extractor so that if a fault is detected, effectively everything turns off.

On a side note - is there any benefit to setting up the AM882 to run using a common PC+5V vs, the other way with the common PC-gnd? On the PDMX manual it has a pic with typical connection for leadshine, showing the Common +5V PC as the setup.Which one should I choose?

[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.

[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.