EtherCAT hardware requirements questions

Hello,

I’m in the process of building a small but fast 3-axis mill and have some questions about potentially using LinuxCNC over EtherCAT with it. This is a very conventional design, with just servos and limit switches as necessary inputs/outputs.

I’m going to be using Delta B3 x/y/z axis servos with multi-turn absolute encoders and drivers, which are available in an EtherCAT configuration. I’m also going to be using a servo for the spindle motor, but it will be a different brand with an encoder and a normal driver, not EtherCAT.

My three primary questions:

1. If I decide to run the EtherCAT versions of the Delta B3 servos, what additional hardware would I need to get to be able to control a single non-EtherCAT spindle servo?
2. What configuration/setup issues can I expect to run into with this hardware? Is this a reasonable configuration that should be fairly well supported, or am I on the edge and can expect a bunch of tinkering to get it all working?
3. Are there any reasons to think that I may not be able to use real-time encoder data for the four servos for things like rigid tapping?
   
   Thank you in advance for any help you’re able to give me.
   
   Callum

Step/dir for spindle servo?

Why not ethercat servo for the spindle?

Ethercat servos cost a bit more but mean you don't have to pay for other interface hardware

Kind of putting yourself in a tough spot. You don't need a motion controller with EtherCAT drives so having 1 non-EtherCAT drive will require you so have something for just that drive.

If you're doing EtherCAT you should go all-in.

The only reason for the non ethercat spindle servo is because I already have one. It’s a 3.7 kW 12k rpm servo at 400 Hz.

I suppose I could look into getting an ethercat driver that could run it, but that’s not something I’ve looked into and would add considerable expense.

You might be able to use an ethercat step/dir module. Beckhoff have one. There are plenty of others

or maybe modbus, if you dont want to spend for another vfd.

Also maybe you can try to control vfd over arduino which you can hook up via EtherCAT.

www.bausano.net/en/hardware/easycat.html

Some thoughts on the options above:
- EtherCAT and Mesa: Will work fine. Could be an option if you don't have EtherCAT interfaces for DI DO yet
- Arduino/ Bausano EasyCAT: Having realized a 64DI 64 DO + xxx Slave with this approach, I can confirm that it is viable, but it gets you deep into tinkering territory.
- Modbus: Seems to be one of the most sensible options. A USB to Serial Stick isn't too expensive and mb2hal will you get pretty much everywhere. Not suitable for RT control as far as I know, but this may not be necessary.
- A Driver that supports EtherCAT and works with CIA402 would be quite simple to get to work.

@rodw: I was not aware of an ELxxxx Card that does pulse generation. Do you mean e.g. EL2521? Looks like there is an lcec driver for this, but I am not sure how it works. Could be a bit of an adventure;).

If you have a VFD, modbus (which I used with ethercat), or PWM from Rtelligent IO module, 

@GuiHue, EL7041 is also an option but it includes an input for 48 Volt power for stepper motors.