RS232 different pin outs.

[Mad_Professor]

SO I'm messing around with LIRC, and managed to get two lirc instances to work on an old machine running ubuntu. So I tried to set it up on my fileserver, it has one onboard serial and one header.

I dug around and found a serial header cable, plugged it in and got everything setup and emitter on com1 or /dev/ttyS0 worked fine, but com2 or known as /dev/ttyS1 didn't work. I played with it, bios, drivers, lirc, nothing worked, even though it should!

So I pulled out the meter and measured the pins and the ones I need is DTR pin 4 and ground pin 5. I get 10 volts on pin 4 but get -10 on pin 5 going from ground to ground? Then I checked the working com 1 and get 10 volts on pin 4 and 0 on pin 5, I measured again to be sure and it occurred to me that the old header cable I had dug around for, was wired incorrectly. Verifying this with the supermicro x9scm manual, it doesn't say but I assume it's in order of 12345/6789NC, because my header cable does 13579/2468NC.

I don't mess around with serial much,
So what gives? Why did it change? and whats the new straight thru wiring called? and where can I buy one?

[brethin]

Re: RS232 different pin outs.

RS232 header cables are not all the same and motherboard makers used various pinout configurations which required their header cable from a standard cable. It can be a pain in the ass but most provided a pin for pin layout of the port in the motherboard documentation and a simple rewire of a header cable will make it work.

[Mad_Professor]

Re: RS232 different pin outs.

God damn it, why can't they stick to the standard.

I dug around for more serial port cables, found a handful, all odd/even pin out, so I took one apart and desolder all the wires but pin 1 from the port then used my DMM and probe each wire and solder it to it's respective pin.

It works now, and works well.