This information describes the hardware and software requirements of
the CAT (Computer Aided Tranceiver) System in the FT-727R.
Four connections are used by the CAT SystemL three at the CAT jack,
illustrated below, and one (Signal Ground) at the outer contact of the
MIC or EAR jack.
DO NOT SHORT THE OUTER CONTACT OF THE CAT JACK TO GROUND!!!
[Diagram of the CAT plug:
Looks like a stereo audio jack of the appropriate size.
The outer sleeve is +6 to +12 V DC (Battery Voltage) I do not think this line needs to be connected.
The middle contact is the Serial KeyCode Input.
The center contact is the Serial Meter Output (00h to 0Fh).
See the manual for further description.
All serial data consists of single byte binary codes sent at 4800
baud, TTL levels, with two INVERTED stop bits and one INVERTED start
CAT Control consists of duplication the keystrokes that can be made on
the tranceiver keypad by sending the corresponding keycodes to the
Serial Keycode Input contact of the CAT jack. The most significant
four bits (MSD) correspond with the key column and the least
significant four bits (LSD) correspond with the key row. The Function
key (on the side of the tranceiver) is simulated by setting bit 7.
Results are identical to those described for manual operation in the
FT-727R Operating Manual. Serial Meter Output is sent approximately
every 100 ms while receiving.
[Table for the codes. The lines in  are the original values in the
Yaesu handout, and are followed by the corrected lines as determined
by KB7ABA. Remove the lines in  to see what should be the right table.]
[ @ FUNC F E D C B ]
@ FUNC 8 9 A B C
[ @ NORM 7 6 5 4 3 ]
@ NORM 0 1 2 3 4
E +RPT SIMP -RPT PMS P SET
1 2 3 V c
D SAV-T T-DEC T-SET TX-M S/CH
4 5 6 M MR
B SAVE T-ENC SCAN MC Shift
7 8 9 C <=>
7 LOCK BATT BEEP DUP Step
* 0 # V/U D