I wanted to use my FT-847 as an HF Data radio. I could not get the CAT to control the frequency of the rig, which you really have to have to allow the QSY function to work. I am using a SignaLink USB for the sound and it keys the rig via it's built in VOX circuit, so I didn't run into that funky problem with the Ft-847 selecting the audio source based on the PTT source. The SignaLink worked fine for audio.
I saw that the FT-847 wasn't showing the "CAT" on the front panel display when I was running VarAC. I looked over the VarAC_cat_commands.ini file and noticed there was a VarACStartCmd line. Checking the Yaesu manual there is a command to start and stop the CAT functions on the radio. I added these two strings to the FT-847 section of the cat_commands:
VarACStartCmd=0000000000
VarACExitCmd=0000000080
That has seemed to cure my issue. Here is a screen shot of the settings for the FT-847 Rig Control
I hope someone finds this helpful.
DE N4RFC - Bob - Woodstock, GA