DannyMan

Regarding using a USB to serial RS232 adapter with a PLC. The chance of success relates to which USB to serial adapter you are using, or rather what quality it is. The cheap Chinese adapters adapters from ebay usually uses a Prolific chipset and drivers. These usually won't work with any PLC. The higher quality adapters uses a chipset and drivers from FTDI. There are much more reliable and works with many PLC's, but probably not all. I have had success with several Allen Bradley and Mitsubishi PLC's.

Yes, definitely a shame Linux isn't used in more industrial devices. The only industrial Linux devices I have been working with are the industrial grade wires and wireless routers, with DD-WRT firmware. Very good products.

One thing to check is that the COM port in your new computer provides sufficient power to the 09 cable. If Im right then your COM port is a RS232 port, the cable converts to port to a RS422 port, but to be able to do this the converter needs sufficient power from the COM port. I believe it needs 5VDC, but not sure about the voltage.

Luckily all ladder programming builds on the same basics so actually you can simply find a cheap used PLC of any model on ebay and start practicing and make your own checklist.