I too have the TU-PTA100E-S, and although I tried everything (I lost days!) I couldn't find the discrete codes for On/Off (maybe it's a TOAD). However, I came upon a workaround: the tuner will switch off only if the Power button is pressed longer. So you can use for Off a sequence of two consecutive On/Offs (use links) and for On, you can use any figure button, e.g. 0 or 1. A macro or sequence can then be used to bring the tuner on the desired channel or state.

I did not gave up, I plan to ask Panasonic about the codes, although I have no big hopes on this...

Lix