Controlling Pioneer DVD-V5000 DVD Player via 9-Pin RS-232 Serial Port

All right, let me preface this by saying: I'm not completely confident this is programming-related. I'm trying to use software to solve a problem, but the software I actually trust; I suspect I'm doing something wrong with the hardware. However, I don't know where else to ask this question. Superuser already shot me down, and the Gadgets FAQ makes me think it's not a good fit there, either. If this question really strikes you as too off-topic to permit here, do what you gotta do. But, please. If you could go either way, I beg for your mercy.

I have a Pioneer DVD-V5000 player that I'm trying to control via 9-pin RS-232 port. (As opposed to the 15-pin port that's hard to find cables for.) Trouble is, I can't get the thing to acknowledge any commands. I'm not even getting any error messages back; only silence.

I have the specs for communicating with that port in front of me, and as far as I can tell I'm doing everything right; I'm sending two-character ASCII commands followed by a <CR>. I've gone into the Advanced Setup menu on the player, and have selected the 9-pin port (factory default is the 15-pin). The spec seems to be indicating the 9-pin port is perfectly standard; I don't see any indication I need some kind of custom cable to be using it. And I'm following all the setup protocols from the spec: 8-bit data length, 1-bit stop bit, no parity. Baud rate can be either 9600 or 19200, depending on the Advanced Setup, but neither works.

I'm fairly sure the software handling the COM-port commun开发者_运维百科ication isn't the problem. I've used a version of this software to successfully control another device, and I'm getting identical results (no response whatsoever) when I try to manually shove through commands with a serial port terminal.

Is there anybody familiar with Pioneer's serial-controlled electronics who can give me some suggestions about where I'm going wrong, or for other avenues of investigation?

For the sake of anybody else in a similar bind who stumbles across this question, I'll swallow my pride and record the correct solution, rather than just delete this into oblivion and pretend I was never this dumb. (Topicality hawks, I'm now far less worried about you nuking this thing.) The solution is unrelated to the specific hardware. It's all about the RS-232 cables and what NOT to do with them.

Specifically, if the F-F cable you have is too short, do not use a M-F cable as an extender -- or, if you do, use two of them. Regardless, your total number of cables MUST BE odd. What's Pin 2 on one end is supposed to be Pin 3 on the other end -- but if you have an even number of cables, then Pin 2 on one end goes to Pin 2 on the other end. This is wrong, and whatever gadget you're trying to talk to will rightfully ignore you. You will get very frustrated, fruitlessly Google away trying to figure out what you did wrong, and post lengthy questions of dubious topicality on your favorite Q&A site.

And seriously, who needs that?