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by anonymous
Hi, Can anyone confirm the operation of the relays on a TRB141. I am finding that the NO "Normally Open Contacts" on the relays to be open only when the relays are described as "closed" in the I/O status page. Over my years of experience, a relay being closed, means it would be energised, eg the coil energised with the NO contact pulled in to a closed position. I guess I can live with this, but it seems back the front. With no supply to the unit, the Relay"0" contacts reflect the correct description. I realise that Relay"1" is a latching relay.

Any Comments

Regards to all Alex

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by anonymous


Yes, you are correct. The relay state on TRB141 is inverted. When the state in the WebUI is open, the "normally open contact" is closed. The correct behaviour would be for the switch to be OFF when the state is open and the switch should be ON when the state is closed. However, the issue is that there are many clients with configured I/Os, and changing this would break everything and cause many issues.

Regarding the 2 output relays - one is latching and the other one is non-latching. You can refer HERE for more information.

Kind Regards,


by anonymous
Thank You Andzej. All clarified.    I can see that changing this would cause more confusion. Now I know, we can live with that.

Regards Alex