organtechnology wrote:PEDSCAN is stand alone and the PDS needs the MERGE2 board.
Correct. PDS is usable with one of (master controllers) MRG2, MBBS, or MIDI128. An advantage is when the PDS encoder is mounted on the pedal board, only the small, 4 wire 1.5m (5ft) cable connects it to one of the above master controllers which would be mounted in the console. Up to 3 expression pedals can be connected to a PDS as well. Power for this board is provided by means of the (above mentioned) 4 wire cable.
Another possibility is to use the BBSP board that does not need a matrix but connects to 32 individual pedal contacts. This board also connects to a master controller (mentioned above) by means of a small 4 wire cable which also provides power (for the board).
https://www.midi-hardware.com/index.php?section=prod_info&product=BBSP&R2=USDThe PEDSCAN scans 32 contacts arranged in a 4 X 8 matrix and requires a MIDI DIN cable. Also 5-12V DC power. It has connections for a single analog expression pedal. One advantage is that this board is (super) small.
Rgds,
Ed