Step / Dir to Analog

[Chaz]

In theory if you have a micro-controller with D to A which gives the required resolution you could write a fairly simple program to vary the Analogue output based on step and direction inputs.

That's what I thought too, doesnt sound too difficult to solve, does it?

[Chaz]

So it's been pointed out that the Panasonic drives I have (And are looking to use for the Lathe) can take Step / Direction. Its called Command Pulse.

[m_c]

That's what I thought too, doesnt sound too difficult to solve, does it?

For basic step/dir to analogue, it's fairly straightforward, and there are a few options about, all aimed at spindle control where open loop is usually fine.

The problem is you want to close the loop, which means the interface has not only got to accept the step/dir, it also has to be able to take an encoder input, and control the analogue output with PID parameters. Sounds simple, but given the development involved, support costs, and the relatively few likely to sell, it's not really viable. I'd guess you'd be looking at over £80 per interface to make it commercially viable.
For anybody wanting to use analogue drives, it's usually cheaper to just buy an analogue capable controller.

I do seem to remember there was one available at some point, and IIRC it was mentioned on the Machsupport forum, although I don't remember anybody who actually used any.


However, as you've discovered, most digital drives do support step/dir. It's ye olde analogue amplifiers that are stuck on analogue.

[Ger21]

The Larken Step2Linear board can convert step/dir to analog.
http://www.viperservo.com/