Both of the boards look to me like they expect signal relative to a common ground (labelled DC-). The E0 and E1 terminals on the SBASE could directly drive a relay without the intermediate logic-level circuitry on those boards. It doesn’t show any obvious place to connect directly to the relay on those boards. If I were doing this, I’d just be connecting two relays, one each directly to E0 and E1, and skipping the signal board.
It might work if you set the black jumpers to L, then connect:
- either one of the E0+/E1+ positive lines on the SBASE to DC+ on the relay board
- GND to DC-
- E0- to IN1
- E1- to IN2
two 10K or so resistors (“pull-up resistors”):
one from DC+ to IN1
one from DC+ to IN2.
Then when you “turn on” E0 or E1, you are really connecting to GND, pulling the voltage on the IN1/IN2 signal ports low, to turn on the respective relay.
@donkjr — does that make sense to you? See anything I’m missing here? I haven’t played with any of these relay boards, so there could easily be something I don’t know about them, and figure you are likely to have a clue here. @Jonas_Concepcion note that I’m a programmer not an EE and I’ve let the magic smoke out of a few boards…