ok,

this should be straight forward,

there are examples in that protocol doc.

copy and paste it into TTD as the asci code, clicking the hex button will then convert it between HEX and ASCII and back again.

power on 'L 48B7' (hex 4c 20 34 38 42 37)
standby 'L49B6' (4c 20 34 39 42 36)
YC-1 'L 3CC3' (4c 20 33 43 43 33)

you will need to use a null modem adapter.

it will take a short while between powering on and being ready to accept the string to change to the YC-1 input.

hope this is of help.