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Author Topic: Connecting a VFD to Mach4 through Modbus (RS485)  (Read 818 times)

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Re: Connecting a VFD to Mach4 through Modbus (RS485)
« Reply #10 on: April 20, 2019, 12:26:21 PM »
Does this address all the issues discussed in topic=34023.0 i.e. Estop, speed overide, ...? If Mach4 supports modbus, I think it should be documented and the software setup to handle typical spindle functions as a minimum. Browsing the forum and piecing together various experiments (great stuff there and thanks for that) to get something working seems like a poor way to support a significant capability.
Re: Connecting a VFD to Mach4 through Modbus (RS485)
« Reply #11 on: April 20, 2019, 03:35:37 PM »
Hi,
there are a couple of ways that an Estop event can be handled.

The traditional manner and still is the norm in industrial machines is that an Estop (or limit switch event) depowers
the entire machine by causing the main supply contactor to drop out.

Another way more common on hobbyists machines is that when an Estop occurs then Mach will turn the spindle off.

The objection to this later method is that it relies on Mach (a computer program) to do its thing, should the program
prove to be buggy the machine might not shut down. In many countries that would (legally) be considered unsafe.

I participated quite heavily in:
https://www.machsupport.com/forum/index.php?topic=34023
Zuxtah had relay to depower the VFD in the manner common in industrial practice. He could also have chosen to add
a line or two of code to cause Mach to command the VFD off in response to an Estop.

Speed override is a Mach function. Thus if you override the speed then Mach will increase the commanded frequency
of the VFD and the spindle would speed up. The code to do that was discussed quite extensively.

Quote
If Mach4 supports modbus, I think it should be documented and the software setup to handle typical spindle functions as a minimum. Browsing the forum and piecing together various experiments (great stuff there and thanks for that) to get something working seems like a poor way to support a significant capability.

One of the perennial complaints about Mach4, and to a certain extent Mach3 which preceded it, is that the documentation
is not up to it. The reality is that NFS is a very small company and does not have the resources to employ technical document
writers. Any documentation has to be written by the person who has just developed the 'new' feature and simply put their time
and energy is best devoted to development.....rather than prosaic documentation.

This is why the forum is so important to Mach....we the users sort of document it as we go.

Craig
My wife left with my best friend...
     and I miss him!