Gantry oxyfuel / plasma type machine from scratch

Hello all, I am rebuilding an old gantry type machine which I plan to use for cutting mostly with oxyfuel and eventually for thinner plates with the plasma source.  The machine is 10m long on Y (longitudinal axis) and about 5m wide on X (transversal axis).
I would like to use linuxcnc and I have bought many years ago the servo motors and drives from DMM Tech, more precisely the DYN4 
series. I have 2 motors for the Y axis which I plan to use in parallel (1kW each motor) and a smaller motor to move the torches on the X
axis (a 750W one). All motors have a single turn absolute encoder.

Now recently I have visited some exhibition and I saw today most of industrial things are on EtherCAT. I saw that LinuxCNC supports it 
in the latest versions, but since I have no experience with EtherCAT I would like to ask if I have to pay some special attention to certain things or there are no troubles at all with the compatibility ?

My plan is to make linuxcnc act as an master node, and send signals to the motion controller which will then through some adapters transform the signal to pulse/dir and send to the drives.

This is the general idea on how this should be working. 

Can I hear some comments from you guys , anybody have a similar setup , should I go some other way around the thing ?
Thanks for the time.

Welcome. Have a look in the ethercat section. There are a couple of stickies. There is a seperate Ethercat master application that runs on the Linuxcnc  PC and there is another driver that connects Linuxcnc to the Ethercat master which in turn talks to all your slaves. You should be able to use a Beckhoff analog input (0-10 volts) to read the divided torch voltage. Other than that, it will be similar to what Tommy described for Mesa hardware. The Beckhoff modules are rated for over voltage of 500 volts, same as the Mesa THCAD. I'm uncertain that other brands of analog inputs have this protection. I can't help with oxy.

I recently bought an old plasma + oxyfuel machine to retrofit and resell. I awaits me first finishing some other projects. I plan to connect ethercat servos directly to a linuxcnc pc. I have not yet studied the serial interface for the big XPR plasma power unit that came with it. On a previous project I used mesa + THCAD, never heard any complaints from that one.

In an Ethercat world, I think you can use a Beckhoff 0-10 volt analog interface as it has similar over voltage specs as the THCAD. People have cracked the Hypertherm Ethercat machines here. But do use industrial Ethercat cables in a HF world

Hello Tommylight, many thanks for answering. So if I understand well I should not bother with EtherCAT at all for this. I was looking at the Mesa board and seems reasonable to me.

Right now I have a doubt on the encoders signal feedback. I see the board has only one input for the encoder feedback. But I have 3 drives, so should I leave the encoders
signals from the drive to linuxcnc out ? Or there is a way to connect all 3 encoders to the board ?

Also has LinuxCNC some settings to make the preheat , and open the various gasses vales at ceartain time already in or should I be doing this from zero up ?

Hi RodW, many thanks for answering. Seems you are telling me to use an EtherCAT Beckhoff module for the THC ?

Should I be using only Beckhoff modules or can I go with any other producer, there is a lot of stuff out there. I was evaluating Triomotion modules for motion controll, IO and Analog IO. The Flexslice series (www.triomotion.com/public/products/flexsliceExpansion.php). Seems they should work with LinuxCNC.

Hi NWE, thanks for commenting. Can you share more details on what are you looking for to use for the retrofit ?

Ethercat is very good for motors, but for slow I/O is only expensive and modbus may be better choice...