The manual for the DX100 says it sends program changes yet mine refused to do so. Here is how to make the DX100 send program changes.
To send program changes you must have “ch info” set to on (as the manual says). What the manual does not mention is that “sys info” must be set to off. Importantly, after you set “sys info” to off you must also first press the Internal Bank and select any program in that bank to start program change transmission. If you press other banks program changes are not sent until you first press bank 1 (the internal bank). After this program change is always transmitted until you turn off “ch info” or turn on “sys info”
Not sure if this is a bug or not but it will help to think of it as one – turning off “sys info” does not turn on program changing until you first select program 1 (internal bank, patch one).
By the way, when “sys info” is on, the DX100 transmits the sysex for the patch on each patch change.