TI 500 Series Controller

I have an older model Texas Instruments 500 Series Controller (not the newer 505 series) of which I do not have a backup of the logic. It appears to have a RS-232 port that I can attach a PC to. Question is: What software is necessary to communicate with this device? I do have TISOFT 505 Version 7.1. Can I use that? I did not want to run the risk of accidentally erasing the program from the PLC by trying something I should not. I am comfortable with programming, but I am just trying to get the knack for proper interfacing with all the different brands of controllers out there.

I use both the 500 and 505 series controllers with TiSoft v5.0, using the same cable (9 pin to 25 pin adapter for the 500) without problems.