Topics

1

SmartBOB controllers and dedicated accessories / PMDX 424 E-Stop & Fault actions... similar to PMDX 126?

« on: April 04, 2017, 08:36:05 PM »

Drinking in Manuals and Forum posts! The PMDX 126 BOB manual provides some great detail on input actions and filtering in section 6 that I can't seem to find in the 4xx SmartBOB manuals. I'm wondering if the 424 acts similarly, particularly on E-Stop and Fault.  Please point me elsewhere if I'm missing something! 

A couple specific questions on the 424:
 
  1. Is Fault filtered and captured after ~50ms as with the 126, and is that when all outputs (incl. motor enables) are disabled AND Mach4 gets the report?
  2. Are (a) outputs re-enabled on-board if Fault is de-asserted, or (b) does the 424 wait for Mach4 to restart things?
  3. If 2(a) is true, is there any concern about, say, an unintended spindle restart or axis movement, independent of Mach?

Thanks in advance... This will help me design the interface between the PMD 424 Fault input and my 3 servo Fault Outputs.

Ray

2

General Discussion / Connecting ClearPath Servo HLFB signal to PMDX 424

« on: March 27, 2017, 12:10:20 AM »

ClearPath servos will connect directly to a PMDX controller for step, direction, and enable outputs.  The problem is the HLFB signal from the motor is active (on) when a motor is happy, and off when it faults.  The /FAULT input on the PMDX 424 (or 416) needs to connected to the isolated ground to indicate a fault, just the opposite of the HLFB output. Steve Stallings suggested possible solutions in this forum last fall... a relay might work, but the ClearPath HLFB is limited to 30v and 9ma, and that is non-inductive. Plus, you've probably got 3 or more HFLB signals to connect to /FAULT. Has anybody done this?

I've been checking out solid-state solutions, and it looks like the TC4404 driver chip might be a good choice. It's an inverting open-drain MOSFET driver, and you get two of them in an 8-pin IC for about $3 from Digikey, Mouser, etc.  Two of them plus 4 resistors will handle 4 motors. I haven't tried it yet, but I think the hookup shown below will do the job.

I'd appreciate thoughts from Steve and anybody else on this approach... and any problems with the design.

Ray