03-24-2019, 10:02 AM
(03-20-2019, 10:36 AM)Lorenzo Wrote: Why are there 3 connectors GND, IN and Vcc on the relais card?
The relais PCBs with optocoupler use the optocoupler as a switch. The Caliper2PC I/O output port handles a maximum of 25 mA. That is enough to drive the optocoupler's LED but it is not enough current for the relais' coil. Therefore the Vcc is needed. It can provide the current needed by the relais' coil. With most relais PCBs an external power supply can be used to drive the coil. Connecting the relais card to the Caliper2PC interface just use this pin assignment:
Relais Card - Caliper2PC interface (RJ45 Patch cable)
GND = GND (orange / white)
IN = IO - Output (green / white)
Vcc = 5V (brown)