Gantry oxyfuel / plasma type machine from scratch

saxa wrote:

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.

Linux-CNC is the Ethercat master. You just need ethercat slaves. Have a look at the Beckhoff EK1100 and the many various modules that attach to it. Many of these modules have native support in LinuxCNC. There may be other brands of modules available but you would need to write the driver and you'd need to be sure they have 500v or so over voltage protection in case something goes wrong. Beckhoff and Mesa have that.

saxa wrote:

Can you share more details on what are you looking for to use for the retrofit ?
 

I have not yet started shopping for servos for my machine, but I plan to use ethercat servo drives. I'm thinking likely Stepperonline or Lichuan or Delta brand. For I/O I expect to use Mesa or Beckhoff EK1100 with EL1809 and EL2409. I've used both in multiple projects without any problems that I can remember.
If connecting multiple encoders I nearly always use Mesa because Beckhoff encoder counters are so much more expensive.

For slow cheap I/O I used to not like modbus, but tried it some more recently and am pleased how it is performing. This would not do for limit or homing switches, for those you'll want ethercat or Mesa for sure.

NWE wrote:

For slow cheap I/O I used to not like modbus, but tried it some more recently and am pleased how it is performing. This would not do for limit or homing switches, for those you'll want ethercat or Mesa for sure.
 

Thats interesting. I never thought of this either. If you look at this diagram in the docs. it clearly shows what can be run in non-real time mode
linuxcnc.org/docs/stable/html/code/code-...rchitecture_overview

So spindle, coolant and auxillary devices could be modbus and I can see modbus I/O modules locally for < AUD $50 for 16 inputs and 16 outputs. I'm might also play with some now there is good modbus support in hal
 

I wrote about Modbus, because Ethercat I/O is expensive.
Configuration Mesa+Ethercat is more expensive and you need two network ports (some mini computers are enough powerfull but you can't add any cards).
Modbus need only USB port.
You can find cheap Modbus I/O cards on Aliexpress (for example 4 analog and 4 digital inputs less than 10 US dollars).
Of course Modbus is slow so suitable for slow signals.

tommylight wrote:

Yes you should leave them out, as noted above the only usable way for DMM drives is in Position mode as they have a delay in position signal outputs.
Also the encoder input will be used for THCAD if you want plasma.

By "leave them out" I meant to not connect them at all. But then how the linuxcnc will know where it is at certain point ? I will probably loose a part of precision with not connecting the encoders feedback.

tommylight wrote:

Yes there is, Mesa 7i85 or 7i85S should have 4 encoder inputs.

I see this card has a DB25 connector to connect it to the computer I suppose, or does it gets connected to the
7i96s ? Sorry for dumb questions.
Is the DMM Dyn4 encoder output supported by the Mesa 7i85 ?

tommylight wrote:

No, not per se, but LinuxCNC can be programmed as you need it, so a simple G04 P1800 will make the machine wait for 30 minutes at the first cut to preheat the material.
Same for outputs and solenoids, everything can be automated and even add a side panel with settings and buttons and stuff.

OK for this, I will take a look better on it once I install it in a virtual machine.

rodw wrote:

Linux-CNC is the Ethercat master. You just need ethercat slaves. Have a look at the Beckhoff EK1100 and the many various modules that attach to it. Many of these modules have native support in LinuxCNC. There may be other brands of modules available but you would need to write the driver and you'd need to be sure they have 500v or so over voltage protection in case something goes wrong. Beckhoff and Mesa have that.

I took a look at the EK1100 and various modules, thanks. I also checked the Isolation of TrioMotion FlexiSlice coupler P366 and they state it as 1 kV. So this should be ok.

Many thanks Tommylight, seems all clear to me about the mesa boards and encoders.
I will take a look on the mesa website to see how i get all this different boards connected. So, if I got it correctly I need 2 mesa boards the 7i96S and the 7i85S which get connected together. That should work for me.

I will try to take a look on that DMM delay you are talking to. Also because I want to make this machine to work in our shop and I do not care if there is a slight new cost to add to make it go well and precise. I was even thinking of buying the DYN5 servo drives to have EtherCAT if needed. Altogh I prefer to use what I already have, the DYN4, but if needed I can also buy other servos and drives. Then I can always use these DMM ones for something else.

As for the virtual machine, its just more practical to me to make tests and get used to linuxcnc during my work time with my laptop. Later I will set up an dedicated computer. The idea is to buy a new industrial PC for use with the machine.

LinuxCNC will run on VirtualBox and so on and this is handy to do basic testing and configuration. There is a limit on what can be done on a sim without real hardware.