Does VISA upgrade to 3.4 change Serial Port mapping?

[IM-MDA]

Hello,

I have a customer that has a 16-port NI-Serial PCI card.

They were using a NI-Serial driver v1.5 and VISA version 3.0.1 to communicate with there devices.

An attempt to upgrade to the latest NI-Serial driver and VISA 3.4. However, after the upgrade, it seemed as though the mapping of COM port to the physical port changed. (They "shifted" by 3.) For example, the ports were on COM ports 3 through 18 (ASRL3 -> ARSL18). After the upgrade what was connected to ASRL3, was then connected to ASRL15, ASRL4  became ASRL16, ASRL10 became ARSL7, etc, etc.

Now my question is, does this make sense? They have 3 other machines to upgrade, can we expect similar behaviour there? Will the the behaviour be consistent (i.e. shift by 3 or some other value).

Any help would be appreciated.

thanks,
Dan

[MissyS]

Hi Dan,

Did you remove the card when installing the new drivers? Did you install the new drivers on top of the old versions?

When serial hardware is physically removed from the computer without first being deleted from the system, Windows continues to mark the COM numbers associated with that hardware as "in use." This allows you to reinsert the hardware and have those ports keep their original COM numbers. I'm not sure if this is the cause of the shift in numbering of the ports, but here are some steps that might reorder the serial ports back to the original configuration.

1. Power down the computer, and remove the serial card from the computer.
2. Reboot the computer. Select Start»Programs»National Instruments»Measurement & Automation to launch MAX.
3. Select Tools»NI-Serial»Recover Unused COM Numbers.
4. Power down the computer and insert the card.

You'll then have to run the Found New Hardware Wizard once you reboot the computer. On the cabled PCI-232/16, were the ports in the same order in MAX as on the cables originally? Did the reinstallation change the order or just shift everything by 3?

Regards,

[IM-MDA]

Hi Missy,

The card was in the box and the new software was installed over the old.

It does not seem to be a COM port assignment in Windows problem as the same 16 ports were used by the device before and after the install. (That is COM3 -> COM18).

What changed was the mapping between the COM port and the physical serial connector, and it was more of a "rotate-by-3" than a "shift-by-3". So it basically looked like the following table:

COM Port   Serial Port Before   Serial Port After

---

 COM3             1                     14
 COM4             2                     15
 COM5             3                     16
 COM6             4                     1
 COM7             5                     2
 COM8             6                     3
 COM9             7                     4
 COM10            8                     5
 COM11            9                     6
 COM12            10                    7
 COM13            11                    8
 COM14            12                    9
 COM15            13                    10
 COM16            14                    11
 COM17            15                    12
 COM18            16                    13

Can doing the steps you outline in your message resolve this? Or is there another way to edit this maping?

thanks,
Dan

[MissyS]

Hi Dan,

The steps I outlined should fix this problem. The reason it occurred was because Windows discovered the ports in a different order this time. This is not expected, but it sometimes happens. The serial driver will assign the port names as Windows finds them. Normally, Windows would find the ports in an intuitive order, from beginning to end.

This may or may not occur in your other setups. It shouldn't. To try and prevent it from happening, you could follow the steps below when upgrading your software. But, like I said, it is not expected behavior.

1. Power down the computer, and remove the serial card from the computer.
2. Reboot the computer. Select Start»Programs»National Instruments»Measurement & Automation to launch MAX.
3. Select Tools»NI-Serial»Recover Unused COM Numbers.
4. Upgrade the NI-Serial and NI-VISA software.
5. Power down the computer and insert the card.
6. Go through the Found New Hardware Wizard once you reboot the computer.

Regards,