# How to Calculate CRC-16 (XModem)?

**URL:** <https://discourse.nodered.org/t/how-to-calculate-crc-16-xmodem/51292>\
**Category:** General\
**Created:** [20 September 2021 14:36 UTC](https://discourse.nodered.org/t/how-to-calculate-crc-16-xmodem/51292 "2021-09-20T14:36:39Z")\
**Posts on this page:** 1\
**Showing post:** 10

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**Author:** ![Jean-Luc](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/jean-luc/32/89996_2.png) [@Jean-Luc](https://discourse.nodered.org/u/Jean-Luc)\
**Post date:** [21 September 2021 09:58 UTC](https://discourse.nodered.org/t/how-to-calculate-crc-16-xmodem/51292/10 "2021-09-21T09:58:45Z")

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thanks @Steve-Mcl for your help !  
in fact, the CRC calculator gives B7A9 in hexadecimal. See below.  
How to insert this QPIGS string in the inject node to make the calculation correct ?  
like @eddee54455 , my javascript skills are nearly zero. So I defer to people who do.

![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/a/5/a5b29caf6487ba0b50ce70c8bd0576d201387793.png)

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