Hi there, On Mon, 22 Oct 2012, AlbyVA wrote:
I did think about extending the RS-232 cable ... instead of running a RS-232 cable plus USB cable "as-is", just get a 50ft RS-232 cable, splice it, and utilize 2 wires for the USB power. I suppose that prompts the question, which RS-232 pins are unused? Correct me if I'm mistaken, but are pins 4 & 6 thru 9 unused?
You're mistaken. :) It depends entirely on what the manufacturer did. If memory serves me correctly, the Electrical Industries Association made their RS-232-C specification obsolete in about 1970 and that was the last of what they termed 'Recommended Standards' (that's what the 'RS' stands for). The connector in the specification had 25 pins, not nine. On their new 'Personal Computer' :) IBM used a 25 pin connector for the 'parallel' port instead and a nine pin connector for the serial port in contradiction to the Recommended Standard presumably because it would fit. All kinds of variations on these themes subsequently appeared, and it caused no end of headaches for those of us unlucky enough to have to work with the things at the time. IBM used all the pins on the 9 pin connector. I used to know all the pin allocations for the 25-pin connector by heart but had to keep the diagram for the IBM in the back of my diary. Many other manufacturers did whatever they thought they could get away with to make a gadget work. A quick spin on the search engines will give you all you need to know and then some. Incidentally terminating LMR400 is not a job for the inexperienced, and I agree that extending the serial cable is probably a better idea even if you have to run two separate cables. -- 73, Ged. _______________________________________________ pool mailing list [email protected] http://lists.ntp.org/listinfo/pool
