Have the board up and running using micropython. From the Getting started guide I thought that, when externally powered ( in my case 12v) the Relay COM terminal would also show 12V ?
"Via the external power input
Connecting power to the external power terminals will fully power the Automation 2040 W and all functions will operate. The relays will activate when commanded to, the outputs will provide power when activated (providing the same power and voltage as the external power input) and there will be 5v available via the 5v output terminals."
However I have zero volts across COM to NC or NO and the negative Power In terminal? Is this expected ?
Yes, it’s left up to you how you want to use the terminals. What you have across those terminals is continuity. A use case scenario could be grounding something and not wanting any voltage on those contacts.
If you connect your 12 V to the C (common) terminal of the relay, it will be transferred to the NC (normally closed)when the relay is de energized, and NO (normal open) when it’s energized.
The relay contacts are a single row double pole switch.
Thanks and that works - thank you but the getting started guide is misleading
“The relays will activate when commanded to, the outputs will provide power when activated (providing the same power and voltage as the external power input)”
Depending on your application, you can use the two screw terminals labelled “OUT”. These can supply up to 4A from the PWR IN you provide. Relays only make and break an electrical connection, so I agree the guide could have been better worded.
I’ve just re-read that section of the guide, and it is referring to two separate board features:
“The relays will activate when commanded to"
“the outputs will provide power when activated”
Outputs being the two screw terminals below OUT that I mentioned in my last post. It is not referring to the outputs of the relays, since relays don’t have defined input and output sides.