rs232 read problem

[urcang]

We communicate with a monochromator via rs 232 port using a driver developed by the manufacturer. With a x86 pc having win98, we have no problem. However, when we connect the device to a newer PC having winxp, we can't "read" from the device. What we get is an empty string most of the time when we run the driver. Fortunately, trying a much newer third PC with winxp solved our problem. I have some ideas about the problem but I am still far away from solution.To make things more clear, there is also a SCSI device connected to the PCs which brought many conflict problems until we could operate it in winxp. (the problem also accurs when the SCSI card is discarded). Is there anyone having idea?

Thanks.

[ictoan]

Hello,

I also have problem reading RS232 on WinXP. For most parts, I can read RS232 fine but sometimes it just suddenly stops and requires a restart to work again.  The computer is set to be always on so it does not go to sleep. Is there something else I need to do so that RS232 will be connected at all times? Thanks!

[Roland A.]

Hello Urcang:

Have you tried using hyperterminal to communicate with the instrument? When you say you cannot read from the device, what program are you using to do the reading?

[urcang]

Hi Roland,

We use the driver software developed by the manufacturer based on Labview. I used "measurement & automation" software to communicate with the instrument and what I got was the 'timeout expired' error. Also, hyperterminal didn't work. This is what happened in one of the PCs we tried. The problem is that, the device works fine with some of the PCs but not with the others. We could not anticipate any possible reason for that. Two computers having intel processors, one with win98 and the other with winxp( no SP2), works. Two computers having AMD processor and winxp(with SP2) as OS does not. We also tried to uninstall the SP2 from one of the latter PCs, but the result was negative.

Finally, I got an old P3 700mhz PC with Labview 6i and tried it also. At first, software waited a long time(about 5 sec. for each time) for the 'serial read' vi but it was working! Then, I installed the executable driver from the manufaurer and it did work fine(both executable software and labview library are available, the situation about the former PC is valid for both cases). As a result, it seems as if the problem is solved yesterday. But we are not satisfied since we couldn't find any reason for the problem. Any vi developed in an older Labview version should work fine with newer versions, isn't it? Also, one of the PCs that works fine(having winxp without SP2) has Labview 7.1. If the version was the case, it shouldn't work.

Sorry for the long mail, but I wanted to tell the whole story because it seemed to be a little complicated.

Thanks in advance.

[Roland A.]

Hello Urcang:

This is an interesting problem. Have you looked in Device Manager to make sure there are no conflicts, also I'm wondering if SP2 is the issue, from what I read you haven't been able to get it to work on any SP2 machines correct?

[urcang]

Hi Roland,

I checked out the ports from the device manager for all PCs, there were no conflict. I also think that SP2 is the problem but can not be sure. Because when I first uninstalled SP2 from the last PC(wich works fine now) it was waiting for about 5 sec. for each 'serial read' vi(this is what happened when SP2 was installed in this PC). So nothing changed. Then I installed the executable drivers from the manufacturer(also labview based) and it did work. Right now, the problem seems to be due to the vi. library but it was working in another PC. However, all those working PCs are non-SP2 machines where others have SP2. There is no stable behaviour and this brings the problem.

Thanks again.

[shoneill]

It is known that some types of serial ports are "less compatible" than others.

I have seen a lot of problems when using laptops for example, or USB-RS-232 converters.

Maybe the serial ports on your motherboard are the problem.  Have you checked the settings in the BIOS and in the "Device Manager" in Windows?

General rule of thumb, if it doesn't work with Hyperterminal, somethings wrong with either hardware of drivers.....

Shane.