Lost contact with my serial ports.

[phibxr]

Today; my serial ports (ttyS0 and ttyS1) decided that they wouldn't bother talking to me (or to any other external devices) anymore.

I first noticed this when I was about to download some pictures from my digital camera attached to /dev/ttyS0 and received a "timed out"-error from gphoto2.

Just to see if it was the camera or the ports i plugged in my Palm IIIe and ran coldsync, and nothing happened.

I've checked the permissions, and they haven't changed at all. Could it be some kind of IRQ-conflict? ttyS0 and ttyS1 has been assigned respectively the IRQs 4 and 3; although i don't have any more external devices attached.

[bwkaz]

Is some process holding them open maybe? The serial ports may only work with one process at a time, so that if one has them open, no others will be able to open them. But I'm not sure on that. Check with either fuser or lsof.

If you have an RS-232 logic analyzer handy (one of those things that plugs into an RS-232 port and has LEDs for the different status and data pins on the port), try plugging it into ttyS0 and catting a file into it. See if any of the handshaking lines change state when bash opens the file to redirect cat's output to it, and then see if the transmit or receive pins starts flashing quickly.

Alternately, try something like e.g. minicom -- see if it can open the port.

[phibxr]

I've installed Gentoo (coming from Fedora Core 1) since my last post - and they are still dead. This doesn't look too good as I need them for both my Palm and my digital camera and can't afford buying a new motherboard.

What should I do? Are there any USB <-> Serial-adapters or something else that might help me?

[camelrider]

There are (or, used to be available) USB cards that could go into a PCI slot.
I don't know what to do about your serial ports.
>edit<
Have you checked the physical connections for your serial ports all the way from your motherboard out to wherever you are connecting your devices?

[banzaikai]

Fortunately...

Some of us here are old enough to remember all the pins on a DB-25.

I'd hate to concern you, but I think you have a no-power problem. You see, there are these driver chips (or chip, if they use a MAX-232 variant) that convert the 0v-5v logic into the +/-12V RS-232 voltage levels. This is why you have at least one line from the power supply for -12V, and why it usually only outputs ~500mA. Now, if the -12V is shot, or the SMT fuse on the mobo is blown, you'll have no logic "0" on the RS-232, and get a timeout because the TTL side of the chip is working, but the RS-232 side isn't. So, the OS "sees" the chip, but the chip doesn't see the device.

So, you should check the voltage with a DVM. It's the white wire on the ATX plug. If that's good, then start looking in the area around the ports for any surface-mount fuses, labeled either "X#" or "F#", and check BOTH sides of it for voltage. If one side has -12V and the other at 0V (ground), then it's blown and needs replaced (not easy to do, but possible).

If you don't want (or know how) to do this, take bwkaz's advice and get or borrow a simple RS-232 checker. I'm betting that the LEDs won't display anything, or display only red (+12). I fixed someone's mouse problem this way, after finding that the rechargeable battery (old system) had leaked, eating through the -12V line. A quick jumper later, and she was up and running...

banzai "null modem" kai

[XiaoKJ]

Originally posted by phibxr
What should I do? Are there any USB <-> Serial-adapters or something else that might help me?

yes, but I think you may have to recompile a kernel for it

[phibxr]

When I connect the cable from my digital camera I get extremely small, not visible in daylight, blue sparks at first contact. I'm beginning to dislike this.

There are some places around here selling PCI-cards with two RS232-ports. Would it be possible to get one of those recognized by Gentoo, or should i get an USB <-> RS232 adaptor (which is more expensive and only has one port)?

[hard candy]

I would go for the card after checking its compatability with linux. I think the usb adapter would not give you that much more speed (if it's usb2) and it would be something else to keep track of.

[bwkaz]

Which chipset is in that card? Alternately, which card is it?

If it has standard 16550 UARTs on it, then I think that Linux's serial driver can handle it natively, but I might be wrong...

[banzaikai]

from: phibxr
When I connect the cable from my digital camera I get extremely small, not visible in daylight, blue sparks at first contact. I'm beginning to dislike this.


Whoa! This is a classic case of the RS-232 chip(s) I mentioned earlier being shorted to one of the 12V rails on the outputs. Why it's not blowing any fuses or putting the PSU into shutdown is beyond me...

What make of motherboard do you have? It may be possible to replace the chip(s) if they're separate from the southbridge, otherwise you'll have to get a new mobo. Look for small chips by the ports that have "MAX-2xx" or "1488/1489" on them. These will be the RS-232 converters.

As for the PCI add-ons, I'd make sure that they can be set to standard ports with jumpers. IIRC, Boca had some pretty good boards, maybe SIIG... (Googling...)

Yup! Try http://www.siig.com/productlist.asp?catid=6&subcatid=73 to see which one will suit you. Make sure it says DOS compatible, as these will set to standard UART/port settings for Linux, too. My pick would be the http://www.siig.com/product.asp?pid=214 pci-2s.

Remember to disable and tape up your existing ports.

banzai "Recommended Standard" kai

[bwkaz]

We use some of the cheaper (dual-9-pin-port) SIIG cards at work. We run them on Win2K, with the SIIG drivers, but they work great. It's some good quality hardware.

I didn't want to say anything about them in case they were like Winmodems, where you needed the SIIG drivers to get them to work at all. But if most of their cards say they're DOS compatible, then they won't require those drivers after all.