In Patch mode, to receive program change the default MIDI receive channel is 1. From an External source (DAW or Keyboard) you will need to transmit the MSB, LSB and PC numbers on MIDI channel 1 for Patch change.
For Performance mode you will need to transmit the MSB, LSB and PC numbers on MIDI channel 16.
Below is the MSB, LSB and PC information for External control
PATCH Default Receive MIDI CH 1
MSB: 85 LSB: 00 PC 1-64 SYSTEM-8
MSB: 85 LSB: 01 PC 1-64 PLUGOUT1
MSB: 85 LSB: 02 PC 1-64 PLUGOUT2
MSB: 85 LSB: 03 PC 1-64 PLUGOUT3
PERFORMANCE Default Receive MIDI CH 16
MSB: 85 LSB: 64 PC 1-64
Remote Kbd = ON (Must be "on" to play "upper" and "lower" parts from a controller)
The Remote keyboard switch can be found in the "System" settings.
[Menu] -> System -> [Enter] -> MIDI: Remote kbd (use the value knob to select the value "On")
Please note that to receive Program Changes, Remote Kbd needs to be Off.
To play the SYSTEM-8 from an external controller and obey the SYSTEM-8 Key Range settings, Remote Kbd must be set to ON. The same is true if you want to play the SYSTEM-8 Arpeggiator from an external source. Instead of "Remote Kbd = ON (Must be "on" to play "upper" and "lower" parts from a controller)"