simrantogether

Hi..

suddenly all the serial ports available were not working..?

in control panel --- > systems --- > hardware --- > Device manager --- > ports --- > com1 and com 3..

they are working well according to computer.. but the data is not coming out... to hardware..

Sometimes comes .. sometimes not..

Can tell what the problem is...

Regards,

Simran..

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Simran..
8051 Specialist..

JimB

Sounds as though the handshake lines are not set correctly, or just floating.

JimB

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Experience is directly proportional to the value of the equipment ruined.

simrantogether

do you mean ' BIOS '.. that appears when we press delete button again and again.. when the system is rebooting..?


handshake lines means..?

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Simran..
8051 Specialist..

simrantogether

problem that the organisation is facing is that...

all the computers were working well..

but last month slowly and slowly all the serial ports stopped functioning...

Engineers have ruled out possibility of "viruses"..

Hope..

Regards,

Simran..

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Simran..
8051 Specialist..

JimB

No.

I assume you are talking about RS232 serial lines, because you mention COM1 COM3 etc.

In an RS232 interface, there are lines TXD and RXD which pass the data back and forth between the two devices.
There are also lines such as RTS, CTS, DTR, DSR and a few others which control the flow of data between the two devices at the ends of the RS232 link.
To get a better understanding, try goolging "RS232 Tutorials", the first on the list on my PC was:

http://www.arcelect.com/rs232.htm

have a look, it seems to be a good start.

JimB

__________________
Experience is directly proportional to the value of the equipment ruined.

picasm

It could be "Malware" dialer software that is grabbing the com ports when you use the web browser.

Although good antivirus software may detect such things, it is a good idea to scan with an anti spyware/malware program also - such as "Spybot search and destroy" (free and very thorough) and "Ad-Aware" (free version available).

Torben

I second this. If it's happening at the same time on more than one machine, then I'd be very suspicious that some kind of worm or trojan has gotten behind your firewall and is taking the com ports for some reason. I can't think of any off the top of my head which do this, but it's just unlikely that the machines are all deciding to develop the same flaw simultaneously. I don't much believe in coincidence.

Or maybe someone is walking around plugging something into the com ports which is killing them. I doubt this one, though.

By the way, your IT guys haven't "eliminated" the possibility of a virus attack; they have simply shown that the scanner(s) they are using show the systems to be clean. There's a difference. No scanner can find everything, and it is vastly harder to prove that something does not exist than it is to prove that it does. Usually the best you can say is that they haven't been able to find any viruses.

Try the scanners mentioned, as well as HiJackThis. Google will return download links for all of them.

Actually, another idea: was a new service pack or other update, or any new software/hardware/drivers, recently installed to the machines in question? There is an off chance that something like that could be interfering with your software's connection to the com ports. Not terribly likely, but worth eliminating as a possibility.


Hope this helps,

Torben

Tomble

I'd go along with that, I bet dialers are relatively common as Picasm suggested. Probably trying to find a modem to dial some premium-rate line somewhere.

You never know FWIW it might not be just one person with his random device, it might be whatever they're collectively using on the ports as part of the business or whatever, eg if it's an in-house design with some serious flaw. Maybe with somehow very low impedance or something?? ISTR RS232 drivers have current-limiting though, so perhaps they're hard to break.

Ah, but here you're assuming that they must've eliminated that possibility by doing a virus scan. One way I would check the serial ports on a Windows box would be (presumably like Hero999, except I wouldn't propose it as a good time to switch permanently ) to boot up a Linux LiveCD on it, and see if that can use the ports. If a Windows-installed virus can get in the way of that, damn clever trick! In the DOS days (and presumably still) there were IIRC viruses that could screw with your bios, but the only way I can picture that making a difference here is by it mucking up the hardware settings or something. Would that even happen?!

Of course, if Linux was able to use the ports ok, that doesn't mean the problem is a virus or malware. It could be that the machines have somehow had their Windows settings messed up, or that some other, relatively innocuous program, is trying to grab the ports.

And if they couldn't use the ports ok in it, that doesn't mean it's a hardware fault, it could be something Linuxy preventing them from doing it there (eg, device access permissions). But if they knew what they were doing with that, they'd be able to figure that out.

Torben

Hehe. Yes, you're right. There are any number of dialers which could be responsible--I just couldn't think of any at the time to point to. Poor wording on my part. Of course today I was working on my wife's cousin's machine and found the Coulomb dialer on it, so there you go.

And you're also right that I made an assumption about how they proved that a virus wasn't responsible. I still think it's a pretty reasonable assumption based on what I've seen in a lot of shops. But yeah, if they did try a boot from known clean media and didn't give the boot sector a chance to run and still had the problem, then it's a fair shake that a virus isn't to blame. My wording was too strong.

Until that's established, however, a bum dialer (or as you note, a config error--but on multiple machines? Slowly spreading over some period of time?) feels like a more likely culprit to me.

The guy with the port killer device, though: totally possible. Also a change in how they set up the boxes, or as I already mentioned, installation of new software/bum updates to existing software could cause it. But something which would cause the actual hardware on multiple machines to go bad like that over a short period of time (sounds like several days to a few weeks) would almost have to be someone going around plugging in something sufficiently goofy to blow the ports. Otherwise a good clean boot (assuming no BIOS issues or changes) should have helped.

Hm. Maybe they reflashed the BIOSes over a period of days and the updates did something which would require the ports to be reconfigured in the BIOS? Just thinkin'. Of course, you'd have to think the pattern would be pretty obvious in that case.


Torben

flemmard

Thanks JimB...It helps me too !

simrantogether

ya...

till now everything we are checking .. we are able to found no fault..

the thing we are noticing is unique and this problem seldom is faced by anyone..

One trick..

how to check the serial port is working is that..

short pin 2 and 3 on the back of serial port..

go to accessories -- > hyperterminal --> rs232 --> then select the com port that is working.. -- > select the baud rate , select the program flow as ' none '

the start typing anything...

if it appeares on window what you've written.. that means the serial ports are working...

Regards,

Simran..

__________________
Simran..
8051 Specialist..

Torben

Hi Simran,

You say you've checked everything, but Everything is a Very Big Place.

Can you list exactly the things you've checked? The things you've tried? It will help people to not spend time looking for your problem in the wrong spots.

How (exactly) did your engineers eliminate the possibility of a virus?

Have you tried clean-booting from a live CD or, failing that, an old DOS floppy? If so, what happened?

Did anything unusual happen last month? BIOS upgrades, OS upgrades/patches, software/configuration changes. . .etc.

Please, more information!


Torben

ericgibbs

hi Simran,
This method is known as RS232 loopback, see this link.

http://www.airborn.com.au/rs232.html

If a RS232 test program runs ok with a loopback connector then the problems not with the hardware.

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

Torben

I think that if this works, then the problem is also not with the OS, BIOS, or COM port settings, either--unless the test program bypasses these. If it doesn't work, it has pretty much shown only that the problem is probably internal to the computer in question.


Torben

simrantogether

well hi..

thanks for replies..

engineers have ruled out virus because.. there have been formatting of computers..

and also serial ports are new..

Regards,,

Simran..

__________________
Simran..
8051 Specialist..