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Frequently Asked Questions and answers

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Can I connect more than one USB-COM to my computer:

Yes.
You may operate as many serial ports as your operating system supports. In Windows 98/ME this is 128, in Windows 2000/XP it is 256. The limit in Linux is in the kernel, you must change it there.

Can I use the USB-COM in other operating systems than Windows:

This depends on the operating system. It is possible to use the USB-COM in Linux since kernel 2.4.x. The drivers are provided by the manufacturer of the central chip in USB-COM. Please check the website for detailed information about support for your OS.

VScom serial cards and Linux:

The standard driver "serial" in kernel 2.6 supports all VScom PCI-Cards.
Attention Fedora users:
In the core 3 distribution is a bad choice for the serial driver. The maximum number of serial ports is very limited. To change it use "make menuconfig", and modify

Maximum number of non-legacy 8250/16550 serial ports

from 4 to 8. This changes the CONFIG_SERIAL_8250_NR_UARTS variable in the .config file. After building the kernel and rebooting, dmesg will say:

Serial: 8250/16550 driver $Revision: 1.90 $ 12 ports, IRQ sharing enabled

These 12 ports are the 4 well known standard ports (ISA bus), plus additional 8 just configured for a VScom 8 port card. For more serial ports increase the value just more. In fact, it does not cost performance or much memory anyway, so you may prepare it right now.

In kernels 2.2 up to 2.4 most PCI-Series cards are already supported by "serial". Depending on the distributions version (kernel version) this driver may need extensions for some cards. These Patches provide detection information about PCI-Cards, appearing later than the kernel. The early kernels up to 2.4.12 require some extensions to the operation mode. Later only Vendor-ID and Device-ID of some cards are added. The Patches are provided as diff-files, optimized for the distribution of SUSE. Of course they may be used in other distributions also.

In the older Kernel version 2.0 the PCI cards are configured with our tool VSCARDCFG. Just run it on startup, it will establish all necessary settings.

To manually install PCI- or ISA-cards, there is a prepared documentation, describing the installation of serial ports. This is the option always possible, regardless of kernel version or distribution.

Windows 2000 / XP:

The drivers are available in the download area. Known problems:

• The PCI boards have two (or even more) possible speed settings. Installation always assumes high speed, i.e. the maximum bitrate is 921,600bps. Sometimes this is not the real configuration of the board. When the driver is first loaded, it will detect the real configuration of the hardware. Under rare conditions this test may fail.
  Please use the "Check" button in the "Advanced" panel of the serial card.
• ZIP-Drives can operate at the parallel ports. If the port shall be uninstalled, it is necessary to uninstall the drive first. Otherwise Windows 2000 does not boot any more. This is a problem in the ZIP-Driver.

Missing digital signature error:

Some Windows systems request a digital signature from Microsoft, when installing a driver. This request is frequently misunderstood as an error message. But in fact it is not. The driver did not pass the test, because it never participated in it. This is normal, especially with the latest versions of drivers. Not even all of the Microsoft drivers are signed.
Just confirm to continue the installation.

VScom serial cards and OS/2:

In OS/2 serial ports are generally installed using the SIO-driver. The reason is, the standard driver COM.SYS is not flexible enough, to handle various situations. These Instructions show the necessary steps.
Meanwhile IBM has developed more modern drivers. There is PRINT02.SYS to run at least pure printer-port cards, and the new COM16.SYS to control up to 16 serial ports. Both drivers are also functional with PCI cards..

VScom interfaces and Novell Netware 4.10:

Specific informations in this (.pdf) instruction.

VScom serial cards and OS/2:

In OS/2 serial ports are generally installed using the SIO-driver. The reason is, the standard driver COM.SYS is not flexible enough, to handle various situations. These Instructions show the necessary steps.
Meanwhile IBM has developed more modern drivers. There is PRINT02.SYS to run at least pure printer-port cards, and the new COM16.SYS to control up to 16 serial ports. Both drivers are also functional with PCI cards..

VScom interfaces and Novell Netware 4.10:

Specific informations in this (.pdf) instruction.

Operating VScom PCI cards in DOS:

Our boards, including the PCI-series, operate in DOS. However there are important items, to be checked on the target system. When everything is specified, you can find instructions for DOS here.

VScom PCI cards in other operating systems:

Of course it is impossible to give a detailed instruction for all cases. But there are general hints, which should meet most situations.

ISA-cards are installed correct, but do not operate:

Probably the selected IRQ is not occupied by a device, but it is unavailable on the ISA-Bus. These settings have to be changed to correct the problem. They are necessary for all ISA-boards.

How to replace an RS-232 Connection by RS-422:

It's very easy to change between RS232 and RS422, if you carefully pay attention to these items.

ISA-Bus and IRQ-Sharing:

Normally it's impossible to share an IRQ between two ISA-cards. This also applys to different components of ISA-cards. But VScom cards with four and more ports have the possibility to do this, because of a special logic on the cards.
And how to program it? In most cases the operating system is responsible for all these things. If you want to program the hardware directly (i.e. under DOS), you must bear in mind the following items: An ISA-IRQ is not triggered by an activ level, but by the change into the active state. If an IRQ happens the ISR has to treat all possible sources until a complete sequence without any demand is passed. Just after this it is sure, the next IRQ can be detected and triggered by the interruptcontroller.

How to operate COM10 to COMxx:

Very frequently Windows programs refuse to operate with COM10 or higher. What is the reason?

1. The program is an old 16-bit application. In this case COM9 is the highest available interface.
2. The program offers a list of ports, only containing COM1 through COM9. Please contact the programmer.
3. The program does not open the port in the correct way, please contact the programmer. Probably a name like "COM11:" is used to select the port. This is not allowed. The correct name is "\\.\COM11", i.e. with <Backslash><Backslash><Dot><Backslash> as prefix; additional there must not be a colon at the end. This method also operates with COM1 through COM9.

Printer (ZIP, Scanner,...) installation in NT fails with PCI parallel ports:

Description:

The PCI-parallel port installs without problems and error messages. Later a modern printer is installed at this port. Now there are a lot of error messages while printing to this device, e.g. claiming the cable is broken.
This problem is very good known, it also affects ZIP-drives, Scanner, Dongles and other devices.

Technical background:

The printer driver attempts to get enhanced information from the printer, by reading data from the parallel port. Unfortunately the port driver of NT does not support reading data. Please note the difference between the driver for the port and for the printer. So the printer driver uses its own routines to access the parallel port,
bypassing the port driver.
To do this, the driver must have exact information about the hardware. LPT2 is only a name, neither an address nor an IRQ.
The setup programs of common printers fail to collect this information. Especially with PCI these settings are dynamic, and partly (IRQ) unknown to NT. This is definitely an error in the printer software. VS is very confident the manufactures will change this in the near future, since Intel removed the ISA bus from the PC.

Solution:

Please disable the bidirectional communication in the settings of the port and the printer. Then there will be no attempt to read data from the parallel port. No more error messages.

Options:

If you definitely need this extended information, there are two ways to proceed.

1. Get an ISA card for parallel port, set this to Address 0278h, IRQ 5.
   These are the compatible settings the printer driver expects. We also offer these products.
2. Send this information to the manufactfurer of the printer. They should come up with a better installation program. At least the setup program should ask the administrator about the hardware configuration.

Windows NT "Cannot read EEPROM":

Now there is an completely new driver. This does not identify the board by serial number, but by the mechanical position. So the settings get lost if the board is placed in another slot. This driver is available for download.

Following is obsolete information, VS recommends to use the new driver instead.
Frequently (in modern computers) the installation program DRVCONF displays the error message "Cannot read EEPROM" when installing PCI cards. The reason is, the installation program can not read the serial number of the card(s). Later the driver also will have this problem.
The basic source for this is a wrong configuration of the PCI bus. The chipset collects subsequent write accesses, delays them, and later executes them as a burst. While this approach is effective when accessing memory, it massively hinders the access/control of hardware via I/O-accesses. With these accesses the PCI chipset must not use this method, since it destroys a programmed timing. Unfortunately this configuration is out of the control of the user, maybe the chipset itself can not make a difference between memory and I/O.

PRO- and Turbo-series, operating in Windows 2000 and XP:

Vision Systems does not develop drivers for Windows 2000, to install the ISA cards there. The Windows 2000/XP driver from Microsoft should be used. With the PRO-series step to do first is to configure the card using the DOS-utility CARDCONF, before starting the Windows system. Afterwards the card can be used like any other ISA card. The next part of the installation procedure is similar for the TURBO-series. Reserve the IRQ used by the card for ISA-usage.
Open the Hardware Assistant and add as many serial ports as required. Do not perform any reboots now. Open the Device Manager, and in the Properties of the ports open the Resources. For each new port select base configuration 0008. Then configure address and IRQ of the port. When this is finished for all new ports, reboot your system.

This basic idea is also true for any other operating system. However the installation process in the OS will be different.

Operating VScom cards in FreeBSD:

With a little help FreeBSD can operate the serial ports on VScom cards on its own. Here you find the more detailed instructions. VS does not provide a driver.

Possible speed configuration of serial ports (PCI and USB)

The serial ports on the PCI- and the USB-devices of VScom provide many more speed configurations as are offered for selection in typical programs. Especially when connecting very special hardware there is always the question. whether the requirements of the hardware are supported by the serial ports. To offer a fast and easy answer to this question, there are two programs. The SPEED-H+L for the  PCI-cards, and the SPEED-USB for the USB-COM. These programs operate in DOS, as well as in the DOS-Boxes of all Windows and OS/2 versions. They should also operate correct in DOS-Emulators of various operating systems.

There are more technical informations on the backgrounds, separated for PCI and USB.

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