Mach3 VFD control via Modbus using brain file

[A_Camera]

Thanks A!
I for one have printed this to hard copy and filed it in my Mach3 workshop folder.
Do continue,
Regards,
Nick

Thank you. I will continue as soon as I can.

I am actually pretty surprised how little interest there is in both Mach3 brains and the use of RS484 Modbus to control and monitor VFD. It is an industry standard and very common there for a reason. It is an extremely reliable way of controlling machines in generally noisy environment, suitable for many purpose, not only controlling VFDs, but it allows easy adding other type of inputs/outputs which have RS485 interface and Modbus protocol. Even in home environment, for hobby use, I think is very suitable and much better than the one wire one input/output type of solution which is widely spread. OK, as discussed elsewhere, like in every other serial communication, there is a delay introduced, but to be honest, the few milliseconds lost because of the serial communication can be ignored in this type of slow machinery. Advantages definitely overweight the disadvantage of that delay. It is pretty cool to be able to make the VFD do all the things with only two thin wires instead of several relays, using up many inputs and outputs and connecting several thicker wires, which still will NEVER allow the same kind of control and monitor as the Modbus allows. The expansion possibilities are large, adding other extra units with additional digital or analog inputs and outputs is pretty simple as well, just hanging these on the same pair of communication line, since each are addressed, so there is no conflict, each unit knows which one is asked and which one supposed to send an answer.

Reading back values like real RPM, frequency, temperature, output voltage, current, torque or whatever else you are interested to read back is impossible unless you use a communication line. OK, one digital output on my VFD is a pulse output, so I think that could be used for some of that, as well as one analog output cold be configured for another of those values, but it would be so much more complicated to read those two and would need two more wires...

Anyway, I will DEFINITELY use Modbus over RS485 as far as that is possible and see no reason not to. Until recently, I thought that the use of Modbus was out of the question for me, unless I write a plugin to Mach3, so I am pretty happy that this assumption was wrong and nothing more than some configuration and creation of brain file is needed. OK, for the additional functions, what I call "Bonus functions", there is a need for modification of Mach3 windows and some simple macro changes, but that is no big deal, anyone can do it with the free software provided by Artsoft.

[magicniner]

I am actually pretty surprised how little interest there is in both Mach3 brains and the use of RS484 Modbus to control and monitor VFD. It is an industry standard and very common there for a reason.

I suspect many people will shy away from Modbus because the documentation for the cheaper Chinese VFDs is only just adequate to support manual and, if you're lucky 0-10V speed control ;-)

- Nick

[m_c]

The bigger reason is Modbus is seen as being complicated. Which for somebody non-techy, it is. Get a single setting wrong, and it won't work, or at least not as expected, with no easy way to test why for your average home CNC'r.

Combine that with VFDs and Modbus equipped VFDs traditionally being expensive, meaning basic 0-10V DC speed controllers were far more commonplace, and you can see why 0-10V is the more commonly used method for home CNC. Plus it's easier to diagnose, as you only need a multimeter to narrow down where the problem lies.

[Clive S]

Well said it is much better with KISS as everybody is not from a techy background

[Neale]

I'm very interested in this, but then, I am a techy...

It's not because of the start/speed control aspect, as this is pretty straightforward if you have a BOB or motion controller with adequate analogue output. OK, linearity might not be absolutely spot-on but I doubt that for most practical purposes that matters. However, the idea of being able to read back VFD parameters (spindle speed, etc) to display on the PC screen sounds attractive. Personally, I would not have considered this because I had no idea what a Mach3 brain was so would have never gone looking for this kind of information. I've probably missed something obvious, but I don't find the Mach3 documentation leaps out at me. Easy enough to do the basics but you seem to be somewhat on your own if you go just a little off-piste. For example, do a Google search for "mach3 brain" and the best result seems to be a YouTube video. Personally, I would rather have a decent manual in front of me!

But maybe I've just missed some hidden site full of Mach3 docs, so if anyone can tell me where it is... In the meantime, I shall follow this thread with interest.

[Clive S]

But maybe I've just missed some hidden site full of Mach3 docs, so if anyone can tell me where it is... In the meantime, I shall follow this thread with interest

A bit of info here http://www.machsupport.com/forum/ind...ic,8211.0.html

[Neale]

Thanks, Clive - there's a pointer in there that ends up with a few Mach3 tutorial videos which gave some background. However, I also had a hunt around for something about the HY inverters and Modbus, as the HY manual mentions it in passing but gives no specific information on what you can control or monitor. Apparently, HY have used their own very non-standard interpretation of the Modbus standard and although someone has produced a Mach3 plugin which gives access to some of the HY inverter features, I have not yet found the kind of information needed to use with a Mach3 brain.

Still, it has all thrown a bit of light on the "brain" feature, and I'm now wondering if that could be used to, for example, provide a custom Mach3 facility for master/slave homing which my CSMIO-IP/M does not do. Too many distractions from actually getting on and finishing the router...

[A_Camera]

I'm very interested in this, but then, I am a techy...

It's not because of the start/speed control aspect, as this is pretty straightforward if you have a BOB or motion controller with adequate analogue output. OK, linearity might not be absolutely spot-on but I doubt that for most practical purposes that matters.

There is one HUGE disadvantage with using 0-10V, at least with the BoB's I have, is that if Mach3 is not fired up and the BoB is getting power then it will output 10V and random states for the digital outputs. This creates a dangerous situation since the spindle can start spinning when your hands are too near. This situation can never happen if you use Modbus.

However, the idea of being able to read back VFD parameters (spindle speed, etc) to display on the PC screen sounds attractive. Personally, I would not have considered this because I had no idea what a Mach3 brain was so would have never gone looking for this kind of information. I've probably missed something obvious, but I don't find the Mach3 documentation leaps out at me. Easy enough to do the basics but you seem to be somewhat on your own if you go just a little off-piste.

I agree, this is another major advantage of using Modbus, and I will cover that in my next video. I am reading parameters like Output voltage, current, torque, power, temperature, real RPM, RPM stable... and there are plenty more, but to read those and have some use for them you also need to modify Mach3 screens used, otherwise you won't be able to see those. I have just started with this, so I am no expert, but used Screen4, which can be downloaded from Mach. I find it pretty buggy, crashes fairly often, so frequent backup of the changes is really important, but it is free, so why complain? In any case, to make modifications to existing screens is pretty simple.

For example, do a Google search for "mach3 brain" and the best result seems to be a YouTube video. Personally, I would rather have a decent manual in front of me!

But maybe I've just missed some hidden site full of Mach3 docs, so if anyone can tell me where it is... In the meantime, I shall follow this thread with interest.

Yes, I would also prefer a decent manual, but that is hardly going to happen now that Mach3 is dead. The Brains territory is even less documented than the rest. I managed to gather quite a bit of documentation spread around on the Internet about Mach3 macro programming, use and parameters, as well as about some other bits and pieces, but very little about Brains, so that is not really like skiing off-piste, more like skiing off-piste uphill. Yes, the best I could find was also Youtube video, but unfortunately not enough to help me, so I made my own. I don't know if I will write some kind of user documentation later on, because it takes quite a lot of time, but at least I will document my workflow which can be use by others to figure out what to do and how to solve their problems.

[Neale]

There is one HUGE disadvantage with using 0-10V, at least with the BoB's I have, is that if Mach3 is not fired up and the BoB is getting power then it will output 10V and random states for the digital outputs. This creates a dangerous situation since the spindle can start spinning when your hands are too near. This situation can never happen if you use Modbus.

I can't disagree, although in my case I am using a CSMIO-IP/M which is held in e-stop mode by the safety relay until it is explicitly re-enabled. I think that it stays in standby until it starts communicating with Mach3 as well - I'll have to unplug the Ethernet cable while it is running and see what happens!

As I am currently using a Huanyang VFD and given its poor support for Modbus, I'm not going down that path. Still, if it blows up one day and I have to replace it, then I might well look for something that both supports the official Modbus standard and also has a usable manual!

Good luck with this project - I shall follow it with interest.

[A_Camera]

I suspect many people will shy away from Modbus because the documentation for the cheaper Chinese VFDs is only just adequate to support manual and, if you're lucky 0-10V speed control ;-)

- Nick

Perhaps you are right. However, many people use other VFDs than the cheapest ones, so in that group there should be some interest. Even most of the cheaper VFDs have Modbus support, but sure, you must have a technical interest or some knowledge to start with it.