Posted by Sam Stones on 18/12/2017 06:44:57:
… my three year old PC does not have an RS232 (25 pin) printer socket necessary to accept the dongle……
Sam, I think there may be some clarification needed, as Danny suggested. Most of the answers so far have targeted RS232, but I'd suggest checking before you buy any RS232 kit.
Until the advent of USB, most dongles were fitted to the parallel port of a PC. To save space and cost, instead of fitting the typical Centronics parallel printer connector, PCs used a 25-way D-type connector at the PC end – this physical embodiment is used for both serial (RS232 etc.) and parallel communications – so the fact it is a 25-pin device does not mean it is RS232.
Whereas, as has been said above, you can get 9-25 pin adapters and USB to RS232 converters, I suspect neither of those are what you want.
You are almost certainly in the same boat as many who run PC-based CNC who upgrade their PC. If it is a parallel-port device, you may get away with a USB to parallel port converter, but I would suggest you need to identify one which is known to work with that particular dongle before you buy one. Much better, if you have desktop PC, is to buy a parallel port card to go into the PC.
(and don't worry about criticism for using an old dongle technology – although most of my software that needs dongles is USB based, I do have several old applications I use from time-to-time which use parallel port dongles which I could not justify the cost of upgrading!).
Dave
Edited By Dave Martin on 18/12/2017 10:19:33