All the AD5 range will respond to power on/off over RS232,
but you need to enable it in the hidden service menu,
and just to be difficult the procedure for screens 32"
and over is different than for the smaller models.

The installer menu is made up of lots and lots of visually
meaningless codes - play here at your peril!!

Ask sharp tech support for procedure to enter service
mode and change the setting. They may ask you to sign
a disclaimer so that if you screw with the wrong settings
then they can charge you to put it right.

I do not have the procedure to hand but may be able to
get it later from one of the engineers if you have no
joy.

We are succesfully controlling 20", 26", 32" and 37" AD5E
sets over RS232, so iI know it works