# How to add Roland Checksum for a sendSysEx \[Solved\]

**URL:** <https://forum.electra.one/t/how-to-add-roland-checksum-for-a-sendsysex-solved/2690>\
**Category:** Developers\
**Tags:** lua\
**Created:** [February 13, 2024, 6:36pm UTC](https://forum.electra.one/t/how-to-add-roland-checksum-for-a-sendsysex-solved/2690 "2024-02-13T18:36:25Z")\
**Posts on this page:** 1\
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**Author:** ![oldgearguy](https://avatars.discourse-cdn.com/v4/letter/o/f4b2a3/32.png) [@oldgearguy](https://forum.electra.one/u/oldgearguy)\
**Post date:** [February 13, 2024, 9:20pm UTC](https://forum.electra.one/t/how-to-add-roland-checksum-for-a-sendsysex-solved/2690/3 "2024-02-13T21:20:20Z")

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To actually calculate it, the standard is something like sum all the bytes in the array and truncate to 7 bits, or sum all the bytes and subtract from 256, or …

The Roland manuals are usually pretty good about telling you somewhere how it’s done.

Alternatively, if you have an editor like HexEdit, you can take a dump with a checksum and calculate various ways across the data bytes until you match what is there

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