# Downlink buffer from string (url parameter)

**URL:** <https://www.thethingsnetwork.org/forum/t/downlink-buffer-from-string-url-parameter/16544>\
**Category:** Application Development\
**Created:** [August 4, 2018, 1:00pm UTC](https://www.thethingsnetwork.org/forum/t/downlink-buffer-from-string-url-parameter/16544 "2018-08-04T13:00:16Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![gaspar](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/gaspar/32/25844_2.png) [@gaspar](https://www.thethingsnetwork.org/forum/u/gaspar)\
**Post date:** [August 4, 2018, 1:00pm UTC](https://www.thethingsnetwork.org/forum/t/downlink-buffer-from-string-url-parameter/16544/1 "2018-08-04T13:00:16Z")

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Hi

I currently able to send downlink buffer to a device with this function :

msg.id = msg.payload.id; // get device id from param url  
var pl = Buffer.from([0x5A,0x00,0x0A]);

return {  
dev\_id: msg.id,  
port: 1,  
payload: pl  
};

Question :  
I try to get from my url a string and use it to create my buffer. Ex: mynodered/update?id=myiddevice&upd=\0x5A\0x00\0x0A

msg.id = msg.payload.id; // get device id from param url  
msg.upd = msg.payload.upd; // get upd from param url

var pl = Buffer.from( **msg.upd** );

return {  
dev\_id: msg.id,  
port: 1,  
payload: pl  
};

Anyone can help me about that ?

Thanks

---

<div class="post-metadata">

**Author:** ![gaspar](https://www.thethingsnetwork.org/forum/user_avatar/www.thethingsnetwork.org/gaspar/32/25844_2.png) [@gaspar](https://www.thethingsnetwork.org/forum/u/gaspar)\
**Post date:** [August 7, 2018, 12:00am UTC](https://www.thethingsnetwork.org/forum/t/downlink-buffer-from-string-url-parameter/16544/2 "2018-08-07T00:00:29Z")

</div>

Welcome to all to answer my post please.