The direction is independent from the start and the jog command. IF fwd and rev are both 0 I think it defaults to whatever the last commanded direction was, there is no "neutral".
For your start command, hold the start bit high until the .driveactive bit on the input image goes high, when the .driveactive goes high you can turn off the start command.
Same thing applies for the stop just in the reverse order...
Hold the STOP command high until the .driveactive bit goes low, then you can turn off the stop command.
A stop will override a start, try and only have one START and one STOP in your routine, having multiple will cause issues, delays, stalls, etc.
Think of the jog as a momentary pushbutton, if you push it, it moves, if you release it, it stops. Tip, the jog speed (HZ) is a parameter setting in the drive, this is the speed that the drive will jog. For example if your output frequency is set to 6000 (60.00 HZ) and your jog speed is set to 1000 (10. HZ) when you JOG the drive it will run at 10 HZ, if you START the drive it will run at 60 HZ.
I have used a lot of these drives including the 755's if you have any more questions let me know.
Another point, even if you are using ethernet to control the drive, you still need to factory installed jumper between term 1 and term 11, if you remove this the drive will not run. Found this out the hard way, schematic didnt show it on the print so electrician removed it, was beating my head in the wall trying to figure out why they wouldnt run...