[H.O]

There's a picture on the last page of the G540 manual showing exactly what your trying to do.

Connect the negative terminal of you 12V powersupply to the negative terminal of the supply powering the G540. Then connect +12V to one side of the relay, connect the other side of the relay to the G540 output.

[dan j]

There's a picture on the last page of the G540 manual showing exactly what your trying to do.

Connect the negative terminal of you 12V powersupply to the negative terminal of the supply powering the G540. Then connect +12V to one side of the relay, connect the other side of the relay to the G540 output.

Thank you for the reply, I've read the G540 manual, but my setup isn't like theirs. My 12v PS is running on it's own AC input so I'm not understanding why I'd run a wire between it and the 48v supply.

I want to be sure that the wire leading from the relay (to the PS) is the N.O. and the wire going from the relay to the G540 is the COM.

Thank you,
Dan

[H.O]

The G540 outputs are what is know as open collector outputs. That means they act like a switch to "ground" which in this case is the negative of your 48V powersupply.

You connect the negative of the 12V supply to the negative of the 48V supply to create a "common ground" for the two supplies. That way the G540's output can switch the 12V relay - just as shown in the manual.

Note, this is all on the secondary "low voltage" side of both power supplies we're talking here. It has nothing to do with the primary "AC-side".

I want to be sure that the wire leading from the relay (to the PS) is the N.O. and the wire going from the relay to the G540 is the COM.

Now you're really confusing me.... I thought you wanted to switch the relay on and off with the output on the G540. If so you connect the coil of the relay between +12V and the G540 output. Not the relay contact.... Am I missing something?

/Henrik.

[dan j]

The G540 outputs are what is know as open collector outputs. That means they act like a switch to "ground" which in this case is the negative of your 48V powersupply.

You connect the negative of the 12V supply to the negative of the 48V supply to create a "common ground" for the two supplies. That way the G540's output can switch the 12V relay - just as shown in the manual.

Note, this is all on the secondary "low voltage" side of both power supplies we're talking here. It has nothing to do with the primary "AC-side".


Now you're really confusing me.... I thought you wanted to switch the relay on and off with the output on the G540. If so you connect the coil of the relay between +12V and the G540 output. Not the relay contact.... Am I missing something?

/Henrik.

Sorry for the confusion, Henrik. It was 2AM here and I had a brain fart.

I understand what you're saying about connecting the DC negatives of the two PS. I will do that.

Thank you,
Dan