Wrong Payload Size SysEx Message Help

Hi there!

I keep receiving a Wrong Payload Size Ack Code when I try to send an “Update Preset Short Name” SysEx message to the MC6.

I have been able to send other messages like “Controller Bank Up” or “Update Preset Message” successfully so I know I can get the checksum and formatting correct, but I think there something I am missing when it comes to sending ASCII code in the payload.

If anyone has any ideas of what I’m doing wrong I would be greatly appreciative. Here is the link the current SysEx Documentation for reference. (really awesome this even exists btw!)

The payload size has to be the same length as the preset name size. So for the MC6, the preset short name is 8 characters, so the payload needs to be 8 characters .For unused characters you can just fill it with 32 which is a space character.

Glad to know that this API is being used. Are you trying to do some updates programmatically?

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Thank-you, im not sure i would of figured that out. Yes trying to do some wizardry with max 4 live with it. I’ll share more when its finished!

No worries, it should have been documented there - will update.

Looking forward to seeing it. We haven’t got much feedback related to this feature so if there’s any request with functionalities related to this API, let me know and I’ll see what we can do.


For others trying to find the correct payload sizes (until the doc is updated), I noticed one can figure out the necessary payload size by sending “Get” messages as outlined in the SysEx documentation. For example, when I send a “Get Preset Short Name” message to my MC6 it shows an 8 for the payload size in the Return SysEx code.

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I should add them in the documentation, but I’ll just share the number of characters here first:

  • MC3
    • preset name: 10
    • long name: 16
  • MC6
    • preset name: 8
    • long name: 24
  • MC8
    • preset name: 10
    • long name: 24