[Lozzy]

Hello guys,
I am trying to build my own interface card and I need an experienced opnion.

What I am trying to include in my PCB is a spindle ON/OFF signal circuit.
My VFD, a Chinese one, has about 6 terminals that can command fwd/rev/etc spins which utilize 24VDC as inputs.
Meaning if I set function FWD to a S1 terminal, it spins when it detects 24V DC at S1 terminal.
My Yaskawa & Samsung servo drives also have SERVO ON terminals which are 24VDC input, same as VFD luckily.
My previous parallel port-breakout board has 2 relays to do this and I have been using one of this to command START/STOP VFD spindle so far. (no reverse spin, cause I didn't have any need for it)

Now my question is... will it be safe to do the same thing with an optocoupler - like 4N26?
What makes me wonder is the datasheet of any optocoupler saying about CTR and I do not have any information on how much current is required at these 24V input terminals.

I am not talking about PWM or analogue or step/pulse to control VFD/servo drives.
I am talking about a simple 24VDC input to make ON command and wish to know if any optocoupler output terminals can do this open/close task without overheating the chip.
I failed to google about these 24VDC ON/OFF command terminals if they draw current or not. Internal circuits of these drives are in total confidentiality....
Probably another opto-coupler to drive internal circuit? Then I should be safe to do it.
At PWM zero, spindle is supposed to completely stop but sometimes real world is not that ideal and I would like to give very clear GO/NO-GO signals to the drives, that's it.

Thanks for the reading,

regards,
Kevin

PS. I found documentation of Samsung's AC servo drives. 24VDC SV-ON terminal is opto-coupled one. I guess YASKAWA and any VFD would be same?

[Al_The_Man]

The 4N26 can be used to switch the inputs directly, IOW use the 4N26 transistor to sink the inputs to common etc.
Al.

[Lozzy]

Thanks Al !
I am already working on it using KB824, 2-channel optocoupler

regards,
Kevin

[RCaffin]

Opto couplers are not only possible, they are a damn good idea!

Cheers
Roger