Haven’t tried this yet but …

Using this forum post:[Link: remotecentral.com]

3D Button=55USP (3D)3D0xDC

Use HexMake ([Link: files.remotecentral.com])
or GUI ([Link: files.remotecentral.com])

Using 3FG’s reply as a “how to”

Set the following values:
Protocol=NEC1
Dev Main=4
Dev Sub=251
Fnc a=220(0xDC in decimal)

Outputs the following HEX:

Protocol=nec1 Device=4.251 Function=220
Device Code: 04.FB Function: DC
0000 006D 0022 0002 0157 00AC 0015 0016 0015 0016 0015 0041 0015 0016 0015 0016 0015 0016 0015 0016 0015 0016 0015 0041 0015 0041 0015 0016 0015 0041 0015 0041 0015 0041 0015 0041 0015 0041 0015 0016 0015 0016 0015 0041 0015 0041 0015 0041 0015 0016 0015 0041 0015 0041 0015 0041 0015 0041 0015 0016 0015 0016 0015 0016 0015 0041 0015 0016 0015 0016 0015 0689 0157 0056 0015 0E94

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NOTE: The forum post has a reply that mentions a JP1 master file, the latest 1.15 can be found here [Link: hifi-remote.com])
(I have not found how to download the file (unless you have to be registered/logged in)