In the documentation that I posted it says "PC receive the matrix system data" and "PC send controls to matrix". My thought was that those were 2-way formats? I am far from an expert in this area so I could easily be wrong

I should have bought a Calrad switch

In any case, it would be nice to finally have this piece of hardware under rs232 control, with out without receiving a status. But I am having difficulty. Someone please but me in check...
My interpretation of the command string is:
byte1, byte 2, byte, 3, byte, 4
Example on/off:
0x10:0xd5:0x7b
(I am not sure what byte 2 is? Possibly a 2nd command so you can set output 1 and 2?)
This is what I have and does not work

I tried all sorts of variations. I also tried the xController program. I was able to connect, but that's about it.