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Offline stirling

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multiple serial modbus slaves
« on: December 06, 2011, 08:25:08 AM »
In his vid, Art alludes that Mach can communicate with 2 or possibly 4 serial modbus slaves at a time. However I can't see anywhere in either brains or macros or in setup how you would do this. For example in a brain there's nowhere I can see where you specify the slave address. The slave address used by brains seems to be set only in the modbus config dialog and that only allows one. i.e. you don't appear to be able to say slave 1 has these regs and slave 2 has these etc. Does anyone know how to address more than one slave?

Thanks

Ian

Offline stirling

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Re: multiple serial modbus slaves
« Reply #1 on: December 13, 2011, 04:06:02 AM »
No one ever used more than one serial slave?

Offline BR549

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Re: multiple serial modbus slaves
« Reply #2 on: December 13, 2011, 10:01:05 AM »
Ian the Plugin version I believe was suppose to do it BUT last I heard it was broken and it seems the plugin was abandoned and is now an orphin.

(;-) TP

Offline stirling

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Re: multiple serial modbus slaves
« Reply #3 on: December 13, 2011, 10:58:25 AM »
OK Terry - thanks - so with serial modbus it's one slave's your lot - is that right? Makes me think perhaps that event driven serial might be the preferred choice for the THC then for those that already have modbus (pendants for example).

Ian

Offline BR549

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Re: multiple serial modbus slaves
« Reply #4 on: December 13, 2011, 05:38:46 PM »
IAN Let me do some snooping to verify that. I would guess the IMPORTANT question IS can Mach3 handle more than 1 serial port at a time????


(;-) TP
« Last Edit: December 13, 2011, 05:40:38 PM by BR549 »

Offline BR549

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Re: multiple serial modbus slaves
« Reply #5 on: December 13, 2011, 07:57:09 PM »

Offline stirling

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Re: multiple serial modbus slaves
« Reply #6 on: December 14, 2011, 05:49:24 AM »
IAN Let me do some snooping to verify that. I would guess the IMPORTANT question IS can Mach3 handle more than 1 serial port at a time????
I had it in mind that perhaps it actually could be implemented as a BUS topology (as in modBUS  ???), so ONE serial port would do it from the harware perspective. Of course if the (Mach) software can't address more than 1 slave then that's not going to help much.

From your link it looks like it can't be done which is a shame.

Ian
« Last Edit: December 14, 2011, 05:58:55 AM by stirling »

Offline BR549

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Re: multiple serial modbus slaves
« Reply #7 on: December 14, 2011, 10:42:43 AM »
HI Ian , Still not totally sure whether you can or can't. By the looks of the plugin you should be able to address multiple slaves. BUT that may be going through another Modbus unit and then out to more Units indirectly.

I have read where it may be possible thru the Brains side , But brains can be very limiting themselves.

Probably the person to ask would be Peter Homann as he is the supporter of Modbus in the Mach3 world.

I'll give him a shout to make absolutly sure(maybe) , (;-) TP



« Last Edit: December 14, 2011, 10:44:50 AM by BR549 »
Re: multiple serial modbus slaves
« Reply #8 on: December 19, 2011, 08:19:12 PM »
Hi Ian,

I'm a bit late on this one.

Mach3 can handle multiple Modbus devices from a single serial port. To do this you need to have a RS232 to Rs485 converter as multiple devices will need to be on a RS485 bus.

The ModIO I developed has an inbuilt RS232 to RS485 converter. This way you don't need an additional piece of hardware.
http://www.homanndesigns.com/store/index.php?main_page=product_info&cPath=2&products_id=4

If you look at the following engineering note, it shows how to set up multiple ModIOs on a RS485 4 wire bus. You could also use other Modbus devices such as VFDs, PLC etc.
http://www.homanndesigns.com/pdfs/EN007-MC01R1.pdf


I have a plugin that was not written by me that allowed for multiple ModIOs to be set up. Unfortunately, something in Mach3 has changed that has broken the plugin when setting up more than one ModIO.

That said, it is not necessary to use the plugin, as Mach3 has its "Brains" that allow you to communicate with the ModIOs.

Have a look at the following article I wrote on using Mach3 with Modbus. It should explain quite a bit.

http://www.homanndesigns.com/pdfs/Using%20Modbus%20with%20Mach3.pdf

Other than that, ask questions. :)

Cheers,

Peter.

----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com

Offline stirling

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Re: multiple serial modbus slaves
« Reply #9 on: December 20, 2011, 05:10:22 AM »
Hi Peter - thanks for your reply and the docs.

Now I understand the hardware side of things but I'm still not sure about the software side because...

I have a plugin that was not written by me that allowed for multiple ModIOs to be set up. Unfortunately, something in Mach3 has changed that has broken the plugin when setting up more than one ModIO.

That said, it is not necessary to use the plugin, as Mach3 has its "Brains" that allow you to communicate with the ModIOs.

I've used Brains quite a bit with Modbus but I still don't see anywhere in the Brains interface to address a particular slave. When I first started playing with modbus brains I thought it was the (IMHO) rather poorly named field "Enter Modbus address to use" but that's actually the register number - not the slave address. I see the CFG# field but doesn't that refer to a configuration line in the plugin interface? I can see that would allow you to address multiple slaves via different CFG#'s but that's via the plugin - which you say is a) broken and b) you don't need.

Still confused...

Ian