PMDX Configuration with G540 and VFD

[j2mariashop]

I reopened Mach3 and measured Pin 7 and Pin 8 voltage at varying rpms as follows:

RPM

[j2mariashop]

I reopened Mach3 and measured voltage across Pins 7 & 8 as follows:

RPM     V

100      1.5
300      2.4
500      3.8
700      5.3
900      6.7
1100    8.1
1300    9.5
1500    10.8

I assume this is what one would expect. Under manual control varying the Hz changes rpm proportionally. It looks like only under Mach4 the voltage is a constant 6.6v. There is one thing I noticed in Mach3 (not having run it for a month or so). Spindle acceleration is very slow; on a new S command, rpm drops around 50% before it slowly climbs back up to the commanded rpm. However, it does reach this rpm. Not sure if this has anything to do with Mach4 not recognizing S commands.

Joe

[12strings]

That kind of voltage response is what I would expect.  I presume that is Mach3 with a parallel port connected to the G540, right?

It is very interesting that with the PMDX-411 you always get 6.63V.  I would have expected something close to 0V if the PWM from the 411 weren't working at all.  6.63V is mighty close to 1/2 scale, and is what I would expect if, say, the charge pump signal were actually being output on the PWM pin (even though the charge pump frequency is MUCH higher than the 50Hz recommended PWM frequency).

Do you have the "charge pump" switch on the G540 set to "On" or "Off"?

With Mach4 "disabled", what voltage do you see between G540 terminals 7 and 6?

 Please post  your revised profile (create a new profile package).  I don't have a PMDX-411, but I can try this on my 422 and see what it does with the PWM.

[j2mariashop]

Hi

This is a message from Steve Stallings at PMDX. Steve reproduced the problem on one of their lathes. It looks like the spindle runs fine for Mill but not for Lathe.


Hello Joe,
 
I have reproduced your problem on a system here.
 
Everything works properly on a Mill configuration using a G540 config
with PWM on pin 14.
 
When I run a Lathe configuration, I see symptoms similar to what
you described.
 
This is going to take more work to figure out where the problem is
happening.
 
Regards,
Steve Stallings
PMDX

[j2mariashop]

Here's an update on the lathe spindle speed issue:

Steve Stallings of PMDX recreated the same issue on their lathe. Here is his reply:


>>>I have reproduced your problem on a system here.
 
>>>Everything works properly on a Mill configuration using a G540 config
>>>with PWM on pin 14.
 
>>>When I run a Lathe configuration, I see symptoms similar to what
>>>you described.

>>>W>hen I take our sample Mill profile and set it to Lathe Diameter mode
>>>>it does seem to work. Something is fishy here.....

A few days later Steve came back with the following work around:

>>>>Open the page at   Config > Mach and it will default to the General tab.
 
>>>>In the second column of options at the bottom is a block called Spindle Mode.
 
>>>>Click on Constant RPM and the Apply.
 
>>>>This should make it possible to control your spindle speed. It does not
>>>>solve the issue of how to actually do Constant Surface Speed. I am looking
>>>>into how that works. Seems very few people know and I need to talk to the
>>>>right guy at MachSupport.

So, here I am on MachSupport!

I am running March 4 Build #3481 with a PMDX411 SmartBob [Rev A PCB] with SmartBob USB PlugIn version 0.52.254,  SmartBob USB Bootloader version 1.13.73, and SmartBob USB Firmware version 0.58.205.

Any ideas, anyone?

Joe

[12strings]

So, here I am on MachSupport!

Actually, this is the PMDX support forums.  Machsupport (for Mach4) is here:
https://www.machsupport.com/forum/index.php?board=94.0

Or wait for Steve to go back channel to them and get the answer.

[MichaelSmith]

Very helpful thread I found here. Very detailed explanation and simple to follow. Thanks for this.

[Surfmaster]

Thanks for starting this thread, I learned a lot from it.