Feature request - Revers primary and secondary relay functions

Hi again, I’m suggesting a way to revers primary and secondary relay functions.

To be specific: Use secondary relay as primary relay, while using primary relay for something else (warning light for “Max. unattended operation” for example).

An explanation of my situation:
I currently have one bridge’s secondary relay hooked up to my Shopbot CNC’s input, and set it up a pause switch. Without the bridge activate, the CNC won’t run, and if the user is unattended for more than the set amount of time, the machine will “Pause” (instead of stop if I hooke the control power directly to the bridge primary relay).

The setup works great so far, except the CNC is too distracting and too loud for user to notice the small flashing light on the bridge, or it’s warning sound. If I can set primary relay as the warning light relay (while using the secondary relay as the primary), I can set up a huge warning light as we usually do with the secondary relay.


Hi Jason,

try to look at this, maybe it will help you.


HI @fablabvan,

sorry for the late reply.

Why don’t you use the bridge’s primary relay to do that job? Then you could use the secondary relay to control the warning light – just as it was intended.

No worries. Do you mean disconnect the primary relay from the main power source and use it just as a relay? If this is possible, it should work. Is there any documentation on that anywhere?

The reason I ask the reversion of primary and secondary relay functions, is because I won’t need to change the wiring of the fabman unit, and my LED works on main power anyway.


Hi @fablabvan,

have a look at our connection schemes for V2 bridges. It contains various examples for connecting machines to Fabman bridges. Let me know if that‘s not enough and you need more information.

Best regards,