[PabloMack]

I have been using grblShield with Arduino Uno for a couple of years on three machines that I have. With a new machine build I decided to upgrade to using an Arduino Mega 2560 and a driver that supports 4-axes. It is a Chinese made box sold by <www.omc-stepperonline.com> part number ST-6560V4. It interfaces with a parallel port which is targeted at the UnixCNC/Mach market. It provides a 10A relay. What is this normally used for? I send the company an email several days ago and they haven't responded.

[CitizenOfDreams]

Such a relay could be used to control a spindle, a coolant pump, a vacuum pump, a dust collector or any other device with G-code commands.

[Al_The_Man]

Reading the manual, there is an implication that there is both an input and output for external control of the relay, No mention of typical functions?
It could be a general purpose use or even use as a E_stop relay?
It doesn't appear to show any connection to the P.P.?
Al.

[CitizenOfDreams]

My Chinglish is a bit rusty, but I believe the manual says that the relay is controlled by pin 17 of the parallel port. As for the "typical function" - I guess controlling the spindle would be the most common use for it.

You may need to make some additional connection though. I could not make enough sense of the line that says "Connect to the collector of NPN in relay, and connect to 24V through relay".

Oh, wait, I get it now. The relay is controlled by pin 17 of the parallel port through a transistor, but you can also turn on the relay by pulling down pin 8 of the "Manual input" connector.

[Al_The_Man]

I am never surprised at some of the Chinese manuals or instructions.
I recently contacted Huanyang factory for some clarification on some points on their VFD's as there is a lot of seemingly hearsay information posted here by some.
I did receive a reply but it contained contradictions as did the Factory-origin set up videos, that looked like someone in their basement had put them together, I also had a chuckle from the 'Technician" who was using an old moving coil meter for the instructional.
Incidentally no grounding was used whatsoever!
Al..