A discussion of the programming cable choices...
For those who might be wondering which of the available (retail or Internet) programming cables they should purchase for their GRE-made, RS-sold scanner, I thought I'd throw this out...
1.
Your computer has only a serial port, no USB ports. You really only have two choices. You can buy RadioShack's 20-289 cable or the one from
www.pfranc.com. I'd recommend the latter. Too many reported problems with 20-289. There are designs for superior cables, but you have to build them yourself.
2.
Your computer has only USB - no serial ports, and you don't have any other "serial" devices you want to connect. Two choices again: a USB-serial adapter plus one of the cables from (1) above, or the new RS 20-047 USB cable. I'd highly recommend 20-047.
3.
Your computer has only USB - no serial ports, and you have (or may soon acquire) other serial device(s) in addition to your scanner(s). You're going to need a USB-serial adapter for the "other" serial device(s). Now you need to decide how you want to connect the scanner. You can either get one of the cables in (1) above, or you can get the RS 20-047 USB cable. I recommend the USB cable - it costs $5 more (than 20-089), but is more likely to "work". You can also connect it to a separate USB port - letting you use 2 devices at once.
4.
Your computer has serial and USB, and you have only the scanner. Your choices are between one of the cables in (1), or the RS 20-047 USB cable. Again, I'll recommend the latter.
5.
Your computer has serial and USB, and you have (or will acquire) serial devices in addition to the scanner. Same choices as (4). If you get the 20-047 USB cable, you can connect the scanner without disconnecting the other serial device.
(In 4 and 5, you actually have another choice: a USB-Serial adapter plus one of the cables in (1). It costs more, and increases your cable count, but will give you an additional "general-purpose" serial port you can use when the scanner isn't connected.).
For most people (myself included), the 20-289 serial cable works just fine - either on a built-in serial port or when connected to a USB-Serial adapter. For other people, however, this cable's inherent design problems keep it from working on their built-in serial ports. Moving to another computer, inserting a USB-Serial adapter, or even swapping the 20-289 cable at RS for another sometimes solves the problem - sometimes it doesn't. The pfranc cable is better. The home-built cables (esp. Bill Petrowsky's) are, in my opinion, the best.
The 20-047 cable was actually designed from the start to work with past, current, and future GRE-made, RS-sold scanners. It does contain a USB-Serial converter, but does NOT contain the TIA-232 transceiver. This eliminates the 20-289 cable's problematic conversion circuit. It also lets you run at higher bit rates than '232 - if a future scanner supports such faster rates.
So... If you have USB ports on your computer, I'd recommend the 20-047 cable. If you don't have USB, you can try the 20-289 serial cable (or the alternatives).
When given the choice (i.e. your computer's hardware supports a choice) between the 20-047 and 20-289 (or other) cables, there are a few factors to consider. These include, but are not necessarily limited to, price, cable count, using multiple devices at once, and likelihood of the cable "working":
- At worst, 20-047 does cost $5 more than 20-289. At best, it's cheaper than a USB-Serial adapter plus 20-289.
- At worst, cable count is a wash; at best, you eliminate a USB-Serial adapter cable if you use 20-047.
- If you only have one available serial port (with or without an adapter), 20-047 allows you to connect multiple devices at once.
- Finally, and perhaps most importantly, 20-047 is more likely (than 20-289, at least) to work.
(A note to head off a question: No, I don't receive any benefits from RS's sales of the 20-047 USB cable - unless you count the lack of 20-289-related support requests as a benefit (and I do!).)
)when data is been transferred. 
