serial ports not working...

[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..

 

[JimB]

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

JimB

 

[simrantogether]

hi...

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

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

handshake lines are not set correctly

handshake lines means..?

 

[simrantogether]

problem..

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..

 

[JimB]

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

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:

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

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

JimB

 

[picasm]

Engineers have ruled out possibility of "viruses"..

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]

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).

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 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'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.

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

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.

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.

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]

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:

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

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

JimB

Thanks JimB...It helps me too !

 

[simrantogether]

ya...

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..

 

[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]

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..

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

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

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

 

[Torben]

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

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

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

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]

hi...

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..

 

[Torben]

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..

Hi Simran,

Formatting won't eliminate all viruses. Boot sector viruses will survive reformatting--the format will destroy everything on the drive except the virus.

Also, you still haven't explained whether you've checked the ports by booting from live CD and tryed to access them from there. You can download live CD ISO images for free (google "ubuntu live cd").

Bottom line: you need to check the hardware with a completely clean boot.


Torben

 

[blueroomelectronics]

Try booting from a linux CD (the kind that run completely from the CD)
This will eliminate the Windows OS and its virus or whatever from the problem. You can then test with any linux terminal program.
https://distrowatch.com/dwres.php?resource=cd

 

[Tomble]

Hi again,
Uh, Simran, if I read your comment correctly then maybe the loopback test you described would not completely prove that the hardware was ok, because you said you only connected pins 2 and 3, and turned off the flow control. So what if somehow it was just the flow control pins that were at fault? I'm not sure if it's possible for that to happen, or for that matter for some virus etc to grab just one pin of a port- it sounds somehow unlikely, but the whole situation sounds kinda weird anyway The loopback circuit shown on the page Eric linked would be more complete.

And, if you can access the serial ports from hyperterminal, which is just a Windows program like any other, then this also implies that Windows can use the serial ports??? So in what way do the ports "not work"?

Can you maybe tell us what you use all your serial ports for in your company? What software do you NORMALLY use to communicate with what hardware, or is that like some sort of a secret?

(BTW, I would still agree that the Linux LiveCD approach to testing the serial ports is a good idea, BUT you would need someone who has enough experience of using Linux to do that It isn't the same as using Windows)

Finally, as for proving that there can't be viruses or malware on the systems because they have been formatted: REMEMBER! Not only is Torben's comment about "boot-sector" viruses a possibility, but also maybe some of the software you reinstalled after formatting is "malware" already: IE, some programs are "trojan horse" programs that companies give away free because they will install other stuff on your computer at the same time, like dialers and spyware.

Free software in general isn't all a bad thing- many ordinary people (eg, me!) write programs just because they want to! But you have to worry when a company seems to only exist to give you something at no cost, because they might be up to no good. You see the difference, yes? Perhaps you don't have any software like that there, though.

 

[Tomble]

(very OT following what I'd just said: There are obviously also good reasons for companies to give away software too: In some cases the software is like "added value" to make an informative website even better, so they can get more money from advertising; in other cases it might be as a "loss leader" to make something else they actually sell more valuable to people, like where Microchip give away software for programming PICs. So it's not all bad! But it's still something to be careful of, and it's a good idea for Windows users to have malware scanners)

 

[ericgibbs]

And, if you can access the serial ports from hyperterminal, which is just a Windows program like any other, then this also implies that Windows can use the serial ports??? So in what way do the ports "not work"?

Can you maybe tell us what you use all your serial ports for in your company? What software do you NORMALLY use to communicate with what hardware, or is that like some sort of a secret?

Hi Simran,

I would ask you these same points as Tomble wants to know about?