# Newbie question: writing a value to a BACnet AV

**URL:** <https://discourse.nodered.org/t/newbie-question-writing-a-value-to-a-bacnet-av/85911>\
**Category:** General\
**Created:** [26 February 2024 07:23 UTC](https://discourse.nodered.org/t/newbie-question-writing-a-value-to-a-bacnet-av/85911 "2024-02-26T07:23:00Z")\
**Posts on this page:** 1\
**Showing post:** 9

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**Author:** ![WarrenL](https://avatars.discourse-cdn.com/v4/letter/w/eb9ed0/32.png) [@WarrenL](https://discourse.nodered.org/u/WarrenL)\
**Post date:** [26 February 2024 23:42 UTC](https://discourse.nodered.org/t/newbie-question-writing-a-value-to-a-bacnet-av/85911/9 "2024-02-26T23:42:35Z")

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Hi Billy,

The clue was in this thread I found a little while ago, in which the OP was having the same trouble as me:

> [@Use external value for BACnet write node?](https://discourse.nodered.org/t/use-external-value-for-bacnet-write-node/42469):
>
> I have been using the node-red-contrib-bacnet library and everything is working perfectly, I can read and write values to my BACnet controller without an issue. I do have one problem though, I cant figure out how to use the value from another node like a timestamp as the value that is sent by the BACnet write node. When I do it like this it writes the value perfectly: But it does not work at all when I try to use the msg.payload from another node: I have tested the msg.payload it…

The node help wasn't much help, but iiLaw's answer made a few pennies drop. I took his function node and butchered it a little:

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/d/1/d17b4addd62c6af51fbf8637b33f2a3a0afe7954.png)

![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/4/e/4e455eaaaf7030dc105c73249d4c6e58744482db.png)

And now I have the Open Weather temperature writing correctly to the AV. Phew!

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