The 8th byte of each MIDI message is a channel number. This message enables every channel for MIDI. The RM50 comes from the factory with only channels 1+2 and enabled.
There is no way to enable sysex reception via MIDI, so the user must change the device ID (Utility:MIDI:Device Number) from off to any number manually.
For Help file: Setup the RM50 for FreeStyle by enabling a Device ID number.
To do so, press the Utility button and then the Page buttons until you see the MIDI page. Press +1/Yes. Press the Page buttons until you see the Device number page. Enter a number.
A value of 1 (one) will work fine unless you have more than one RM50 on the same MIDI port, in which case you should give them each unique numbers. Do not use the All setting.