Top Six Slippery PCI Serial Port Card Setup Problems: Part 1

This article and the next cover a range of installation difficulties that go a bit beyond the simple scenarios of not having drivers, or not having a free slot for adding a card.

They are hand-picked by Ian, our LAVA tech most conversant with troubleshooting problems that customers see when installing LAVA hardware.

While all of these issues have occurred in the installed base of LAVA products, most of the problems have causes that could apply to other manufacturers' products as well.


Well, it seems every now and again people run into problems installing PCI serial port cards, and at times they can't be faulted for being baffled: there are situations when the problem is arcane or unusual. LAVA's top tech support guy talked to me about just those sort of tricky problems. With literally millions of LAVA serial port cards in the field he's seen pretty much everything. Here's what he came up with:

1) MF.SYS file problem

This problem shows up with Windows Vista and Windows 7. For reasons only known in Redmond, Washington (if even there), these two versions of Windows have moved the location of the file "mf.sys" from where it has resided since the beginning of Microsoft time to a new location. The relocation was unannounced and without precedent, but there we are. The result is that a message along the lines of "service installation invalid" appears upon the installation of a PCI serial (or parallel) card that uses this system file.

The explanation and troubleshooting instructions for this issue are available on the Microsoft website at:

  http://support.microsoft.com/kb/926171

Despite what this web page says (that the mf.sys file is not installed in Windows Vista), the instructions given make it apparent that the file is simply in a new location. Follow steps 1 to 5 on this web page and you will be back in business.

2) Incorrect driver selection

People make mistakes, and this is a common one: installing a 16650 UART serial port card using 16550 UART drivers. For a start, that is not likely to work. But the complication really arises when the person installing the card realizes their mistake and then tries to install the correct driver: they get nowhere. More precisely, the re-installation goes half way but does not complete. The issue is that installing the new driver does not clean away all the files from the initial installation.

When faced with this problem, the solution is to follow steps that will fully remove the wrong installation before proceeding to install the correct driver. Step-by-step instructions are here, or can be found on the installation CD that came with your LAVA card.

3) Computer will not boot with card installed

This is a hardware incompatibility problem. This problem, showing up primarily but not exclusively with new Dell systems, is a conflict between the chipset on some older LAVA boards (and older boards from many other manufacturers as well) and some newer motherboards' BIOSes. The short history is that the industry interpreted the PCI slot specifications in one way for a long while (years) and more recently some motherboard manufacturers have implemented a previously-unused signalling requirement, following the PCI specification but not following what was conventional in the industry.

The solution to this problem is to contact LAVA. With specific information on your LAVA product and your motherboard we can verify that this is the problem and determine the appropriate solution.


This concludes Part 1 of the Slippery Six; we'll cover the remainder in our next article.