This is usually very straight forward. Use the grey DB9 serial cable to connect the PC to the 705.
Then follow the setup instructions below copied from
http://www.splitsecond.comTAG Heuer CP 705
When connected to a computer the CP705 is used as a time source. The idea is to set the timer up so all the work is done on the computer. There's more than one way to do this with the 705 but an example would be to set it up as follows:
Modify Date . . . .
Time . . .
Free Memory . . . . always a good idea to clear the memory
Select Sport . . . . Alpine
Select Run . . . . either, doesn't matter
Numbering Cntrl . . . . Manual, won't be doing it anyway
Press the Red buttons to disable blocking of the inputs!
Input 1 is Start
Input 2 is Finish
Use the "view raw data" screen in the Split Second "setup and test" to see the data being transfered.
The 705 will now become a "time base" and the operation of your race will be done on the PC with the SST software.