[mactec54]

I was thinking that I might be best off using a breakout board. This one looks like it might be suitable:

https://store.dmm-tech.com/products/...breakout-board

as it is specifically sold to control their analog AC servo drives and their drives take instruction from the same RS233 / RS422 ports.

I am starting to get the feeling that nobody here has actually used the Yaskawa SGDA drives so people are confusing me with guesswork and assumption.

All CNC machines are controlled by a computer. Even if it uses a custom operating system instead of Windows, it still needs a method of communicating G-code (or equivalent) to output instructions to the drives. An "industrial controller" is just a PC. Using this piece of logic, and the fact that there are many YouTube video showing people running SGDA drives from a PC, I can deduce that it can be done and that my drives do not in fact predate the desktop computer....

For anyone that has used these drives, there is a simple answer that goes something like "I connected my SGDA drives to my PC using this cable, board or card".

I have some of these drives even some a generation older than your drives, but I prefer the SGDH Sigma II Drives or the newer current Drives

The Dmm Breakout Board is Step/Dir only was designed to be used with Mach3, but any other controls that have Step/Dir output could use this board, there Board is custom for plug and play with there servo drives so not much use to you

You can use a $5 to $8 Breakout Board for what you want to do, yes any computer can do what you want to do even a tablet with a USB port can run most control software

[skrubol]

You could use that, that's a standard parallel port to step/dir breakout but has a feature you don't need (the High voltage filter)

This breakout has nothing to do with RS-422, it just an interface from a parallel port (or parallel port pinout motion controller) to up to 5 step/dir outputs
with charge pump and spindle analog out features

No, it doesn't look like he can. According to the model number of his drives they appear to be analog input only.

IF the drives accepted step/dir, this would be easy, but it doesn't look like they do, so you need something with analog output and encoder input. The only analog on that DMM board is for a spindle and wouldn't be suitable for a motion servo.

[PCW_MESA]

No, it doesn't look like he can. According to the model number of his drives they appear to be analog input only.

IF the drives accepted step/dir, this would be easy, but it doesn't look like they do, so you need something with analog output and encoder input. The only analog on that DMM board is for a spindle and wouldn't be suitable for a motion servo.

Take a look at the Sigma series SGM/SGMP/SGDA manual on page 214:

OP's part number is SGDA 04 ASP

P means position mode and that it accepts step/dir inputs

EDIT Oops, you are right, I had the wrong P, the S means analog speed mode, the P means SGMP motor (page 213)