Random E-Stop events in Mach3 via ESS even though there E-Stop LED on PMD

[EricMack]

I recently replaced my CNC4PC C32 BOB with a PMDX-126 board. While I am still learning, I find the PMDX-126 board well designed and a delight to use.

MY CONFIGURATION
ESS -->> PMDX-126 -->> MACH3
I also have the PMDX-107 and PMDX-179

PROBLEM:  I'm getting random E-Stop into Mach3 via ESS even though there E-Stop LED on PMDX-126 is OFF

I'm not sure the PMDX-126 is actually the source of the problem. I just want to know if there are some standard things to look for.

Apart from a possible issue with the PMDX-126 (unlikely) I think this could well be a (self-inflicted) problem in how I have shared the E-Stop signal and ground with my KBIC Controller and my PMDX-126 (See this post: http://www.pmdx.com/PMDX-Forums/index.php?topic=332.msg1386#msg1386 )

Here's what that looks like:

E-STOP SIGNAL  ---+-->> PMDX-126
                                        |
                                        +-->> KBIC "ENABLE" input

E-Stop, PMDX-126 and KBIC share common signal ground.


One thought I had was to disconnect the shared E-Stop and Ground wires between the PMDX-126 and SIGM/KBIC driver and see what that does, but before I make any more changes I thought I would seek your guidance on common ways to troubleshoot random E-Stop signals into my ESS even though the PMDX-126 E-Stop LED does not show an E-Stop condition.

Thanks.

Eric

[Bob at PMDX]

If you don't see the red EStop LED on the PMDX-126 turn on, then the electronics on the PMDX-126 are not generating the EStop.  The PMDX-126 has an EStop pulse stretcher on it.  The PMDX-126 will *always* output an EStop pulse that is at least 1 second wide, even if there is a very narrow pulse on the EStop input.

We have seen instances where noise couples into the EStop signal between the PMDX-126 and the PC's parallel port.  I can't recall if we've seen this when using a SmoothStepper.  It sounds like this may be the issue in your case.

The usual suggestions are to get the electrically noisy devices as far away from the PMDX-126/ESS as you can (i.e. VFDs or spindle controllers are the usual culprit).  I believe you can also add filtering on the EStop signal (port 1 pin 10) in the ESS plug-in configuration. If so, you can try that and see if it helps.

How long are the ribbon cable(s) between the PMDX-126 and the ESS?  Do you have the ESS mounted on the PMDX-126 using the 6" cables that we sell (or like the ones we sell)?

Bob

[EricMack]

Hi Bob,
- The ESS is mounted ON the PMDX-126 using the 6" cables purchased from PMDX
- Makes sense that this would be outside of the PMDX-126.
- I will explore adding filtering on Port 1, Pin 10 in the ESS Config.

Do you have any concern that the E-Stop signal into the PMDX-126 is also connected to the SIGM/KBIC ENABLE pin and the SIGM/KBIC COM (Ground) is connected to the PMDX-126 Ground?

When this KBIC was used for AhHa the ENABLE was hard jumpered to COM at the SIGM/KBIC but I decided to connect it to the shared E-Stop going to the PMDX-126.

Any thoughts are welcome.

Eric
 

[Bob at PMDX]

It should be OK as long as the KBIC "Enable" input doesn't load down the PMDX-126's EStop input.  Is there a minimum voltage that needs to be present on the KBIC's "Enable" input in order to disable the drive?  Or is it simply "connect to GND to enable, disconnect from GND to disable"?

If you press the EStop switch, thereby opening the connection between EStop to GND, does the PMDX-126 recognize this as turn on the red EStop LED?  And does that also disable the KBIC?

If you have a volt meter, try this:
(1) With the KBIC's "Enable" input connected to the PMDX-126's EStop terminal (and KBIC GND to EStop GND), press the EStop switch to open the contacts to the PMDX-126.  Measure the voltage between the PMDX-126's EStop terminal and the adjacent GND terminal.

(2) No disconnect the KBIC's "Enable" terminal from the PMDX-126's EStop terminal.  Again, measure the voltage between the PMDX-126's EStop terminal and the adjacent GND terminal.

Let me know what the two voltage readings are.

Bob

[Bob at PMDX]

Oh, one more thing: how are you supplying power to the ESS?  Do you have an external +5V power supply (I hope so)?  Or are you supplying +5V from the PMDX-126 by setting JP3 to "On" (hint: don't do that)?

Bob

[EricMack]

Hi Bob Here are the answers to your questions:

1. The KBIC's "Enable" input is simply "connect to GND to enable, disconnect from GND to disable"
2. When I press the EStop switch, thereby opening the connection between EStop to GND, the PMDX-126 DOES recognize this as turn on the red EStop LED. And, it DOES also disable the KBIC,
3. I am supplying power to the ESS via a dedicated external +5V 1 Amp power supply. That is what your manual recommends when I am using the PMDX-126 to supply power to the PMDX-107.

Test results:
(1) With the KBIC's "Enable" input connected to the PMDX-126's EStop terminal (and KBIC GND to EStop GND), press the EStop switch to open the contacts to the PMDX-126.  Measure the voltage between the PMDX-126's EStop terminal and the adjacent GND terminal.
VOLTAGE IS 16.2 VDC

(2) No disconnect the KBIC's "Enable" terminal from the PMDX-126's EStop terminal.  Again, measure the voltage between the PMDX-126's EStop terminal and the adjacent GND terminal. Let me know what the two voltage readings are.
VOLTAGE IS 19.77 VDC. (It would appear that the KBIC provides a 3.5 volt drop when the KBIC Enable line is connected to the PMDX-126 E-Stop.. NOTE: I had my G540 removed from the circuit for this test. The G540 was also tied to the PMDX-126 E-Stop Input)

I hope this information helps provide a clearer picture and I look forward to your next instruction.

[Bob at PMDX]

If you are seeing 16V to 19V between the PMDX-126's EStop terminal and the adjacent GND terminal then you have something connected to the EStop that is supplying that voltage.  This is not necessarily a bad thing, just unexpected.

From your earlier post I presumed that you had a "normally closed" set of contacts on your EStop switch wired to the PMDX-126's EStop and GND terminals, and also to the KBIC "Enable" and "GND" terminals.  Do you have anything else connected to the EStop terminal?

Disconnect EVERYTHING from the PMDX-126's EStop terminal.  Then close the screw clamp (makes for better measurements).  Now measure the voltage from the EStop terminal to the adjacent GND terminal.  You should see something around 3.6V.

Back to your original question - it should be fine with the KBIC enable connected to the EStop input.

Bob