Relay with G540 and a manual switch? 2nd try

[Fastest1]

If I am running a relay on my G540, can I trigger the relay say when not under Mach control and manually operate the relay, do I need to, can or should I diode protect the relay from back feeding?

[MrWild]

I used diodes because I need LEDs telling me things are on and what has it on.

[Pandinus]

If you use a 3 position switch between the relay and the G540, you could have On/Off/Auto modes. As for the diode, I just make it a practice to throw one across the relay coil... cost's a few cents and is an added safety... Although I'd be interested to hear if the G540 has flyback protection built in... again, just a few cents and it prevents the unit from getting fried... with the quality of the Gecko products I'd lay money that it is included in the design... but you never know until you know.

[Fastest1]

Thank you both for your replies. Mr.Wild I am not sure how you used the diodes but I do like led's so if you want to elaborate I will listen. Pandinus why not just a 2 way switch and skip the "off" function (it would be off if in auto mode). So I am taking it that flyback is what I am calling back feeding, correct? After putting this question out there I think the relay has a built in diode. Do either 1 of you have a clue as to how to wire an ammeter into the stepper to see its draw under load? I would like to have a load meter even if the information isnt really all that helpful (yet).

[MrWild]

For an amp meter, you wire it in the drive supply line. It is the drive that draws the power.

I found that if I used a switch, the LED that told me the relay (SCR in my case) was on would light but not say what was powering it. I wanted more than that in having two LEDs that were hooked to either the switch or the G540. Diodes were needed to keep the switch or G540 from lighting both LEDs. Of course it was silly nonsense to wire in two LEDs with the diodes, as looking at the switch tells me just as easily if it is on or not. LED is on, but switch is off, it must be the G540. Anyhow, it was fun figuring the circuit out and wiring it up.