Author Topic: PMDX Support Required  (Read 1192 times)


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PMDX Support Required
« on: August 30, 2020, 04:21:57 PM »
Hello All,
I am trying the forum posting as an alternate method to contact PMDX for support. I have sent two emails and phoned. No answer received. Below is a copy of my request. Please let me know how to proceed.

*****************  Copy of emails   ******************
I purchased some of your products a good while ago. Due to many circumstances I have not been able to install and test the system until recently. I did the testing following your procedure (yes, I read the "Quick Start Guide").  My results have not been good, and I need your help.
First testing - a few months ago:

    The PMDX424 booted, and I was able to communicate with it via USB from my laptop (Win 10). The E-STOP switch worked, but nothing else. No sensors, no motors.
    I took voltage readings on some of the sensors and saw only a change from 0.0V to 0.5V. I think the problem is the Omron sensors EE-SX772. They are powered by the PMDX424 with the open collector output connected to the sensor input. My suspicion is that the leakage current is too high as the output is specified at 0.5 mA max.
    The other sensors were my design error. I used some modules that included an LM339 on the board. I messed up and powered these from the 12V supply on the PMDX424. The 5V IC did what is expected and failed - permanently. I am working to replace those with either a switch or an appropriate 12V sensor.
    I moved on to testing the motors and could not get a response. Two of the motors are Clearpath SDSK series motors from Teknic. I did not get any reaction to jogging the motors. The motors function correctly when using the set-up program from Teknic.
    The other two motors are stepper motors from Automation Direct and Applied Motion Systems. Given the status of my efforts so far I did not move on to testing them.
    I did not have a scope in the shop at the time. I do now.

Second Testing - yesterday

    Installed and licensed MACH4 on a dedicated desk-top PC running Win 10. All appears correct.
    Installed the drivers from your website. All seems normal.
    Powered the PMDX424 - nothing. The orange power light is on and there is no other activity from the board.
    Hoping there was a minor problem I connected the USB to the PC. Nothing.

Products purchased from you: PMDX424, PMDX407, MACH4

How can I proceed from here? I tried your phone bu received no answer after 20 or so rings.

Is there something I can try to re-boot the PMDX424? Can I do some troubleshooting? Can we arrange a time for phone discussion/support?

I anxiously await your return contact. I am a retired electronics engineer so can be available most any time. I am in the Central Time zone (Texas).


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Re: PMDX Support Required
« Reply #1 on: July 15, 2021, 12:42:26 PM »
An update:
After this posting I was contacted by Steve. He was helpful and pointed out that the PMDX-424 manual statement of when the light should be blinking has not been updated. There was not communication issue.

I got the communication working fine. The sensor problems were a combination of several things:
   1) My wiring errors - corrected. Now each individual sensor works fine.
   2) The LM339 based sensors I was using are designed for 5V. All of the components work fine at the 12V level BUT the LED series resistors caused a relatively high current load. After looking up the specifications for the DC-DC converter I found that the current draw when all of the sensors were connected was too high for the module. I replaced the sensors with more appropriate ones and all worked well.
   3) For convenience of wiring I used the SENSOR +12V as the enable for my motor drivers. Any one motor, with no sensors connected, worked. All 4 connected overloaded the module (see above). I re-wired the enables to a different source - issue resolved.
« Last Edit: July 15, 2021, 12:53:32 PM by KenWurtzel »