PCW wrote: No, the diode should be across the relay coil
for example
Sourcing drive:
+24V --> OUT+ --> OUT- --> COIL+ --> COIL- --> GND
or
Sinking drive:
+24V --> COIL+ --> COIL- --> OUT+ --> OUT- --> GND
Diode always goes from COIL+ to COIL- (cathode=band to COIL +)
If you are unsure, test the relay+diode with a mechanical switch
replacing the 7I96 OUT+- pins
As attached?
I'm a bit gun shy about hooking up my torch switch - I plan to use a multimeter to check voltage and current, but the polarity of the 7i96 output switches keeps breaking my brain. I read in another thread that an additional relay isn't necessary (at least for a hypertherm which uses a low switch voltage/current), but I'm tempted to use one nonetheless. I assume the alternative is to just loop through an output pair since the plasma is supplying the signal voltage for the switch (assuming it's a reasonable voltage/current and I send signal+ to OUT+ and signal- to OUT-).
The manual could be more friendly, i.e.
"Inductive loads must have a flyback diode. The output polarity must be observed (reversed outputs will be stuck-on)."
I can see what you mean now, but I interpreted that as flyback diode across the 7i96 outputs (which seemed to make sense since you could force current to only flow in one direction). I was also interpreting the statement about reversed outputs with respect to a diode across the outputs, which seemed to make sense since you would short the switch if you attached the diode in one direction. Big dumb.
It also doesn't say if the polarity sign convention is current flow, or just hook neg-neg, pos-pos. Hence the confusion. I empathise with AgentWD40, I need drawings to understand :blush:
