Just in case you need a TX ground to operate your linear and the CAT/LIN connector is engaged in CAT position (Menu 020).
That was exactly my complain with this Yaesu transceiver! I prefer to use CAT commands to manage all transceiver operations from my computer especially when I operate the digital modes. No way to PTT the linear with such configuration. I had to use a foot switch to do that. Not so neat as I would like. I read several proposals in the internet addressing this issue. None of them was satisfactory for me. So it took me a lot of time till find a solution.
Finally the resolution, even not obvious, is quite cool and easy! In the back panel of the radio there is a female stereo 3.5mm jack called ACC (number 5 in the schematic). You can use this to have TX ground for your linear without sacrificing CAT! If you are interested just follow the procedure.
Open the top cover of the FT-897D and locate the jumper in the back right side (circled in the picture). By default this jumper is set in “TX REC” position. Change it to “TX GROUND” position, as sown on the board, and your work is done. Now instead the TX request feature, described in the operating manual (not very useful to me), you will have a nice independent PTT for your linear.