# Use external value for BACnet write node?

**URL:** <https://discourse.nodered.org/t/use-external-value-for-bacnet-write-node/42469>\
**Category:** General\
**Created:** [11 March 2021 10:24 UTC](https://discourse.nodered.org/t/use-external-value-for-bacnet-write-node/42469 "2021-03-11T10:24:33Z")\
**Posts on this page:** 1\
**Showing post:** 1

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**Author:** ![Graves](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/graves/32/38649_2.png) [@Graves](https://discourse.nodered.org/u/Graves)\
**Post date:** [11 March 2021 10:24 UTC](https://discourse.nodered.org/t/use-external-value-for-bacnet-write-node/42469/1 "2021-03-11T10:24:34Z")

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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:

 ![u1](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/7/8/78bfd1749b6790149ebece14eb2fe9b27f041521.png)  
But it does not work at all when I try to use the `msg.payload` from another node:  
 ![u2](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/f/a/faf768fe8c44b48795baca6146e1249830575f79.png)  
I have tested the `msg.payload` itself and it shows up fine in debug.

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