Serial Port Question

[zonian149]

Hi, I have a Dell OPtiplex 790 running windows 7 64 bit. I purchased the following serial ports Amazon.com: StarTech.com 2 Port Native PCI Express RS232 Serial Adapter Card with 16550 UART PEX2S553 (Green): Electronics. I have installed them and they work great, but only for a few minutes and then the connection is lost. I have been using them running ARC and bctool software. I even tried running Radio Deluxe and it does the same thing. They run great on the serial port that came with the computer, but I cannot get the new ones to keep working. I have the latest serial drivers installed, I have rebooted the computer. I even replace with new ports with a new one thinking I had received a bad one, but it does the same thing. Can anyone offer any suggestions?

 

[Arkmood]

Yeah, I've seen that with addon cards, and the StarTechs are supposed to be decent. Different cables, reseat the card - try all avaliable PCIe slots, comm speed, or, With a lot of srewed up comport intalls I've seen ScanControl worked not bad/ program options /comm rate speed/ set it around 2-5 helps sometimes with the Unidens 796D 250D

 

[aggie72]

I had similar problems and decided to get an old Toshipa laptop running Win98 with a dedicated serial port and have never had any more problems.

 

[WayneH]

try all avaliable PCIe slots

I've had issues in the past with a PCI serial port card and it was related to the slot it was in; so a good option to try. There could be hardware conflicts with where it's currently slotted and other hardware in the system. Often resources are shared and the computer isn't the best at sharing or steering with legacy hardware like serial port cards.

I eventually opted for a USB to Serial adapter (typical UC-232A Aten model) since I wanted the slot for something else and I had the same reliability with USB (if not better).

 

[W2PMX]

Two things:
RS-232 ports normally don't take drivers - the "driver" is in the BIOS (Int 14? It's been a while since I've written serial port software.)

And I've seen serial ports with power configuration - if the port isn't active for X seconds, it shuts off. Since the BIOS isn't written to activate the port (it's assumed always active), and most software doesn't activate the serial port, the port seems to die. Check the port configuration and/or properties to see if there's any power management. If there is, turn it off (usually 0 seconds is off).

Also, in Control Panel/Power Management/Advanced, check the PCI Power Management - it should be off.

 

[searingxheretic]

Two things:
RS-232 ports normally don't take drivers - the "driver" is in the BIOS (Int 14? It's been a while since I've written serial port software.)

And I've seen serial ports with power configuration - if the port isn't active for X seconds, it shuts off. Since the BIOS isn't written to activate the port (it's assumed always active), and most software doesn't activate the serial port, the port seems to die. Check the port configuration and/or properties to see if there's any power management. If there is, turn it off (usually 0 seconds is off).

Also, in Control Panel/Power Management/Advanced, check the PCI Power Management - it should be off.

Good recommendation, I was about to type the same. It sounds like the card is being powered down for a power saving mode, etc.

Sent from my cm_tenderloin

 

[Darth_vader]

Int 03h = COM2/COM4 (BIOS int 0Bh)
Int 04h = COM1/COM3 (BIOS int 0Ch)

If you can, you might also consider trying to run it in 8250 UART emulation mode instead of 16550; if that fixes the problem we can safely rule out power-saving mode. I almost always end up having to do that with Doom II when in network mode, since I almost always end up losing the connection after a couple minutes (which makes the programme hang completely...not the best situation when you're trying to slaughter your way through a troop of skeletons, archviles and a couple cyberdaemons, yet) in the default 16550 mode.

 

[zonian149]

Can you explain that in a language that an idiot can understand. I need a more detailed set of instructions to do what you suggest. Thanks--Gary

 

[Darth_vader]

Basically, the UART (Universal Asynchronous Receiver/Transmitter) is the chip that facilitates communication between serial peripherals and the host computer. There are two different types of UART commonly in use; the 16-bit 16550A and the (way older and slower) 8-bit 8250, both originally produced by National Semiconductor and cloned by pretty much everybody. These days, the 16550A is usually implemented in a composite device like the computer's super-IO device. All 16550A-compatible UART host devices regardless of implementation have to emulate the older 8-bit device to maintain backward compatibility with older peripheral hardware not designed for the 16-bit device. Using 8-bit (8250) emulation on host end can sometimes (but not always) solve compatibility problems between 16-bit host and device, especially if the 16550A keeps dropping the connection to the device or freaking out at the higher speeds, at the cost of performance -- 8250 doesn't have a first-in first-out buffer and only supports speeds up to (if I recall correctly) 9600 baud. (Confused yet? I am. ;o)

I can't give you a specific how-to since I've never had to use a PCI serial adaptor, other than to look it up in the documentation that came with the hardware. On my motherboard's Award BIOS (I use the on-board serial port) there is an option to select which mode to run in (automatic/16550/8250 emulation.) There might be a way to do this directly on bootup if your PCI board has its own initialisation (startup) screen right after passing the system BIOS, but you might have to use properties box for your serial card under whatever the hardware manager is called in Winblow$ 7.

And yes--definitely disable PCI power management, especially if it causes other PCI devices to hang (and it can. Learnt that the hard way with a finicky conventional-PCI Sound Blaster that kept making the system hang and crash.)

https://en.wikipedia.org/wiki/UART
https://en.wikipedia.org/wiki/8250_UART
https://en.wikipedia.org/wiki/16550_UART

 

[W2PMX]

In all the years I've been doing serial I/O, I've never had to run a 16550 or a super-i/o chip in 8250 mode, other than for some pretty weird hardware I've designed. Everything from old 300 baud modems to the latest devices seem to work just fine in 16550 mode, if everything else is set up correctly. (I recently had to rip out the driver for a pretty old USB->serial converter and reinstall it, but the computer is still running in 16550 mode.)

Oh, and you can run an 8250 (or a 16550) with a huge FIFO (interrupt-driven too) if you can find some old AX-25 software. We wrote ISRs for the serial interrupt that ran 3k FIFOs and larger, back in those days. I believe some of the Fido software had them too. The thing is that modern CPUs are fast enough to not really need them, even at Ethernet speeds.

 

[Darth_vader]

Yeah, I know about implementing FIFO for an 8250 in software, but...in hardware?

Doom II (PRBOOM engine) is about the only thing I use these days with the serial port. I usually keep it in 8250 mode, since the game tends to freeze up or lag in 16550 mode because it's some pretty weird software (and that box has a weird motherboard.) The U.S. Robotics V92 modem I ran on that same box until +-5 years ago worked fine in 16550 mode, even down to 150 baud.