Hi I just purchased a used yamaha motif es rack and am trying to use a yamaha p140 to control the sounds. I have them connected by a midi cable and the rack plugged into an amp, but it's not playing any sounds. I've been trying to read the manual as I know they are supposed to be on the same midi channel? I'm new to using midi, any advice would be greatly appreciated.

Not familiar with your equipment (and I'm getting rusty with MIDI), but some things come to mind:

(1) For cables, MIDI IN to MIDI OUT, and MIDI OUT to MIDI IN.

(2) Check the "send" channel of your keyboard (sometimes called Tx channel) - both devices must be set to use the same channel (but you know this),

(3) Turn Local Control OFF, so that only the rack will produce sound (however with it ON it should still produce sound).

G