AXBB hookup question

[dezsoe]

Yes, if your driver is optoisolated.

[RWC]

Just a quick question:
Is it absolutely necessary to provide opto-isolation between port 3 and a stepper drive ?
Is it just to protect the AXBB in the event of the drive shorting out or getting fried ?
Thanks,
Russ

[dezsoe]

Yes, it's for preventing damage, and also preventing ground loops that may occur if there are more devices grounded together.

[cncdrive]

Usually stepper drives have optical isolation on the step/dir lines and if so then you do not need another isolation, the isolation inside the drives will do the job.

[Greolt]

Balazs and Dezoe, thanks for your response.

The drives in my router are older Geckos. I believe they do have isolation.

However they have only three connections for step and direction. 5v, step, dir. Unlike some other drives that require Gnd, step, dir

Port three being a LPT clone has 12 outputs pins, 5 input pins, and 18-25 pins are ground. Extra to that pin 26 is 5v.

So can I connect my drive to pin 26 (5v), and two outputs (say pins 2 and 3)

[dezsoe]

I think, yes. You didn't write the exact type of the driver, but with common 5V it should be optoisolated.

[cncdrive]

Greg,

Yes, you can drive the step/dir opto in the drive with 5V from the 26.pin of the IDC26 port and drive it with any output pins of the IDC26 port.
But as Dezsoe said the drive has to have an optoisolator built in.

[Greolt]

Thank you