It could be an S5-110. It was modular.
Or an S5-100U. It was big bricks.
If it is an S5-110, then I think (not sure) that you had to install a special module in stead of the EPROM module in order to upload or download. So reading from the EPROM may be the best solution.
One problem is the PG675. A dinosaur from a forgotten time. Two floppy drives (single sided 5.25"), one drive for CPM and the programming software (*), and the other drive to hold the STEP5 project files. The formatting of the floppies was proprietary. Even if you could upload or read the EPROM, you would have trouble getting the program printed or transferred to 3.5" floppies.
I would try to locate someone with a never PG, one that can transfer the program files to 3.5" DOS floppies.
If the PLC is an S5-110, then I am not 100% sure that a regular STEP5 knows how to interpret the program. Someone else may confirm it.
* Yes, they crammed both operating system AND a fully functional STEP5 on a singe 360 kB floppy !