So, what to use?
The FDTI chipset is the answer.
For programming Monaco Fire Alarm Panels (mainly M2 addressable) I've habitually used an FDTI "sample cable" they sell for research - really for people to buy who want to develop for their chipset, or rebrand. But you can buy it as a consumer. Here: http://www.ftdichip.com/Products/Cables/USBRS232.htm - though this looks like an updated version of the cable I use.
I also searched for products that use the FDTI chipset, and found http://www.serialgear.com/1-Port-Serial-USB-USBG-232MM.html - which I have tested and used for programming a Versamax PLC. It just works, out of the box (yes, you do have to install drivers...).
Some attached topics of interest:
1) Replace Hyperterminal with TeraTerm Pro. I've been using this a while, I found it while searching for terminal software (free!) that would log my session - because while testing the aforementioned M2 fire alarm panels they spit out a log of device tested, time the alarm came in, etc etc which is nice to round up into a final inspection report. In the beginning I would ctrl-a > ctrl-c the contents of hyperterminal and paste it into a wordpad document - but hyperterminal added things and occasionally lost things, or crashed - I forget the exact things that happened but it happened enough that I knew I wanted something that could log a session.
TeraTerm Pro has been free for a while but is now open source and thus still being developed past the last 1999 edition. Here: http://ttssh2.sourceforge.jp/index.html.en. It does a lot of other things too...
2) Modify the coolgear serial adapter to work with the Versamax PLC. The gender is right, and the cable length is nice (6'). The nuts to either side of the DB-9 port do however need to be pulled side to side then off (not threaded) in order to not conflict with the threaded nuts on the PLC (worth more $ so remains unmodified:) ). Then the blue case needs to be removed (blade slipped between the two halves of the case where the clips are - you can see through the translucent case where. Now the bare circuit board can be plugged into the PLC port with no problem. Careful not to disconnect the PC cable and forget which way round it goes, though - there is nothing to stop you putting back on wrong! See attached photos.
You can also see my desktop ass'y of the VersaMax PLC - I'm setting it up in the office ready to take out to the field. Setting it up here involves learning how to program etc...