# Relays for dummies

**URL:** https://discourse.nodered.org/t/relays-for-dummies/13714
**Category:** Hardware
**Created:** [26 July 2019 11:11 UTC](https://discourse.nodered.org/t/relays-for-dummies/13714 "2019-07-26T11:11:13Z")
**Posts on this page:** 1
**Showing post:** 56

<div class="post-metadata">

### Author: ![Paul-Reed](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/paul-reed/32/66906_2.png) [@Paul-Reed](https://discourse.nodered.org/u/Paul-Reed)
#### Post date: [26 August 2019 22:48 UTC](https://discourse.nodered.org/t/relays-for-dummies/13714/56 "2019-08-26T22:48:31Z")

</div>

Now you've posted the schematic for the door controller, the ground for the door status indicator should be PIN2 and not PIN1.

I wish you had posted this earlier, because I'm now wondering if the electrical path through the opto-isolator will replace the FCA/FCC microswitches and give a false indication if the door is open or closed. This will need to be tested.

![pin2](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/2X/f/f1e942ed0561bc8a50fcff71d92a1fbadde98991.png)

![scheme](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/2X/2/273ef95268d28ecb69d83ff39a730e12d0723b94.jpeg)

---

_[View the full topic](https://discourse.nodered.org/t/relays-for-dummies/13714)._