Hello Guest it is August 21, 2019, 10:28:08 AM

Author Topic: Safer connection from Mach3 to X200 VFD?  (Read 6292 times)

0 Members and 1 Guest are viewing this topic.

Safer connection from Mach3 to X200 VFD?
« on: February 15, 2015, 04:43:04 PM »
I hooked up my X200 VFD (older blue one, not the new black one) into an RS485 link alongside the Ethernet Smoothstepper and built a basic Brain for it.  Speed and RPM control are ok.  RPM control is through the command bus, not PWM.

Problems I noted:

1.  The spindle RPM cannot be displayed on Mach3's RPM field.  I was told this was impossible to do because Mach3, for whatever reason, didn't allow the RPM field to be written via Brains.  Is that correct?  I tried using a Brain to write a constant number to it and no, it can't be written.

2. Mach3 cannot detect that the spindle is actually running.  Or, for that matter, that the VFD even has its breaker on.  It needs feedback for RPM and/or VFD errors I guess and throw an E-stop if it's not there.  But my first note is that is it not always an error for the VFD RPM to be 0 when the Target RPM is 10,000 RPM, because that's normal for the very first moments after the Target RPM is set.  
It also needs to stop trying to send the RS485 RPM command, because if the VFD's breaker is off and Mach3's console has the Spindle left "on"  because of operator error, I'd rather the spindle not spin up on its own when I reset the VFD's breaker.  If it threw itself into E-stop automatically when it didn't get spindle RPM, that problem should have resolved itself with an E-Stop.

3.  My greatest concern here- say Mach3 crashes.  Or the Ethernet cable to the Smoothstepper pulls out.  Or the 120v breaker pops (the VFD is on a different 208v 3ph breaker).  I don't expect the VFD to shut down, it will continue running since it was last given the RPM command and doesn't require ongoing commands to stay running.  How can I institute a hardware failsafe for this?  I have an Ethernet Smoothstepper here.  VFD control is all through the RS485 control bus on a separate link from the PC, I don't want to do with PWM throttle control for it.

4.  I did see a case where hitting Feed Hold stopped the spindle and when Resuming, it failed to restart the spindle.  Why would that happen?  Like I say, it restarted the spindle elsewhere immediately upon powering up the VFD breaker, so it's continuously sending the RS485 RPM command to the VFD.  IIRC in that case I hit Spindle Reset manually to adjust the work, but Mach3 didn't realize the spindle should be "on" again to resume, which is dangerous.






Offline BR549

*
  •  6,886 6,886
    • View Profile
Re: Safer connection from Mach3 to X200 VFD?
« Reply #1 on: February 15, 2015, 05:39:21 PM »
Bringing the VFD into Mach3 though the brains is NOT a good idea. You should use a plugin which has fulll control of Mach3 assets and functions.  As is you have a dangerous situation where Mach3 is NOT in full control of the spindle NOR is the operater protected from the spindle running when Mach3 is offline. Also it is a BAD idea to turn breakers on/off as switches UNLESS the breaker is switch rated.

All Estops should be mechanical in nature NOT controlled through software. Even if you used Mach3's failsafe IT to can fail in a PC crash leaving your spindle running.

There are some examples of VFD plugins in the plugins section you may find one that works for your application or contact the AUTHOR for help making your work with it.
Re: Safer connection from Mach3 to X200 VFD?
« Reply #2 on: February 15, 2015, 05:58:04 PM »
First... you are getting WAY over paranoid about the "What If's" especially with item #3. Years ago I had a boss that was overly paranoid and analyzed everything to death. I called it "Analysis Paralysis"... :)  

If you were using a PLC all the concerns you have could be fairly easily addressed. But now we are talking system design and integration on a much different level.

Most, if not all, VFD's have two programmable output contact (relays) that can be setup to monitor drive functions such as "drive running", "at speed", "Drive faulted", etc. and probably a couple of dozen drive parameters.... as well as programmable digital inputs. And most are Modbus compatible which expands the options. I'm not sure about the older X200 VFD but this stuff has been around since the early 80's. Nothing new here.

You could have the drive monitor the charge pump enable and Mach 3 monitor the drive status via the E-stop input wired in series with the drive relay contact... probably a half dozen ways to make it work. Just figure out the logic to make it happen.      

« Last Edit: February 15, 2015, 06:03:46 PM by geh7552 »

Offline BR549

*
  •  6,886 6,886
    • View Profile
Re: Safer connection from Mach3 to X200 VFD?
« Reply #3 on: February 15, 2015, 06:03:02 PM »
Be Careful of the Mach3 charge pump signal it CAN run with Mach3 crashed.

Just a thought, (;-) TP
Re: Safer connection from Mach3 to X200 VFD?
« Reply #4 on: February 15, 2015, 06:04:30 PM »
Good point BR549.  If this setup is being used in a commercial or industrial application then personnel safety is #1. E-stops can not be a function of a PLC or PC and must be hard wired to be fail safe to remove sources of energy. Only Siemens PLC's has recently been certified to to perform e-stop functions. Siemens fail safe logic is very complex.
 
« Last Edit: February 15, 2015, 06:17:45 PM by geh7552 »
Re: Safer connection from Mach3 to X200 VFD?
« Reply #5 on: February 15, 2015, 07:30:43 PM »
Bringing the VFD into Mach3 though the brains is NOT a good idea. You should use a plugin which has fulll control of Mach3 assets and functions.  As is you have a dangerous situation where Mach3 is NOT in full control of the spindle NOR is the operater protected from the spindle running when Mach3 is offline. Also it is a BAD idea to turn breakers on/off as switches UNLESS the breaker is switch rated.

All Estops should be mechanical in nature NOT controlled through software. Even if you used Mach3's failsafe IT to can fail in a PC crash leaving your spindle running.

There are some examples of VFD plugins in the plugins section you may find one that works for your application or contact the AUTHOR for help making your work with it.

Not sure what you're saying.  Where's this plugin?  It's a common VFD but I've never found a plugin for it. 
Yes I know a stop should be controlled by hardware.  That's what I said.  The question was how.

Offline BR549

*
  •  6,886 6,886
    • View Profile
Re: Safer connection from Mach3 to X200 VFD?
« Reply #6 on: February 15, 2015, 08:01:08 PM »
http://www.machsupport.com/forum/index.php/topic,22806.0.html

In this directory there are seveal examples of VFD plugins.

(;-0 TP
Re: Safer connection from Mach3 to X200 VFD?
« Reply #7 on: February 16, 2015, 04:21:36 AM »
http://www.machsupport.com/forum/index.php/topic,22806.0.html

In this directory there are seveal examples of VFD plugins.

(;-0 TP
But that's a compiled DLL for a Huanyang.  I don't see any way to apply that to this.

BTW I also noted that pressing STOP FIRST commands the spindle off, but the axes kept moving for a short time.  That's super-bad, it's plowing through the material with the spindle running on nothing but remaining inertia.

Offline BR549

*
  •  6,886 6,886
    • View Profile
Re: Safer connection from Mach3 to X200 VFD?
« Reply #8 on: February 17, 2015, 03:18:47 AM »
" you may find one that works for your application or contact the AUTHOR for help making yours work with it."

(;-) TP

Offline BR549

*
  •  6,886 6,886
    • View Profile
Re: Safer connection from Mach3 to X200 VFD?
« Reply #9 on: February 17, 2015, 03:22:19 AM »
Pressing STOP in Mach3 should STOP the axis dead in their tracks NO movement.

(;-)TP