Frequently Asked Questions on VirtPort

Issues with the Windows side

Answer: Virtport is a network pseudo-device driver that allows you to connect a PC-connected serial device to a UNIX/Linux host system over a network, TCP/IP protocol. For the Windows side, the following is required:

1. Your Windows PC must have a network connection.

2. The program can be installed and run by any user. In fact, there is no formal installation procedure; there is just an EXE file.

3. You will generally want the PC to have a static IP address, although this is not strictly required.

4. The PC's software firewall, if there is one, will need to allow an inbound connection on the appropriate port (default 9100). Any external firewalls will need to allow this also.

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Answer: Simply put, Virtport makes a PC-connected serial device appear as if it is local to the host software or vendor application. This is done using TCP/IP over a network where both ends know the other ends IP (network) addresses.

The best example of using this is from one of our customers. An application on this customers Linux host requires a scale for weighing grain trucks. The scale is normally located within proximity to the Linux host. However, they now want to run remote scales located out in the country, but back to the same Linux host. With a network connection and a cheap, small footprint PC at the grain scale running Virtport for the PC, it can talk to the corporate host Linux system running Virtport for the Linx, and all the data for the application will come through as it always has, invisibly over the network to the application.

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Question: How do I run the program?

Answer: The program is a Windows console program, with essentially NO user interface. The command line used to start the program generally contains all the information necessary for VirtPort to run. This command can be entered in any of the usual Windows methods, including a) as part of a BAT file, b) typed in a DOS-prompt, c) typed in Start:Run, d) associated with a desktop icon, etc.

The program is terminated by entering control-C.

If the program is run with no parameters, such as:

c:\virtport\virtport.exe
or
c:\virtport\virtportdemo.exe

it will assume TCP/IP port 9300, and comm port 1. It will display a Windows dialog box asking you to configure COM1 for baud rate, etc.

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Issues with the Host side

Answer: There is a portion of VirtPort that runs on the UNIX/Linux host system. This piece of software is just called "virtport".

On the Unix/Linux side, the person installing virtport must have root privileges. However, once installed, virtport can be run by any user (unless the installed explicitly restricts it using Unix/Linux permission settings).

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Answer: To terminate the virtport session(s), use the 'kill' command to send the process one of the following signals:

SIGHUP, SIGINT, SIGQUIT, or SIGTERM.

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Question: How do I run the program on the host?

Answer: The virtport program must be installed by someone with root permissions. For the following steps, establish root permissions by ONE of: a) login as root (or equivalent), b) run 'su', and specify the root password, OR c) run 'sudo' with each of the following commands.

The virtport program must have its ownership and permissions set properly to run. With root privileges, do:

chown root virtport
chgrp uucp virtport
chmod 6711 virtport

From now on, you do not need root permissions.

Start up virtport with the following command:

virtport -i <IP address or hostname> [<options>] [&]

This command, with no other options, will connect on port 9300 to the PC at the indicated IP address, and will create a virtual device as

/tmp/<username>/virtport.

To launch virtport and put it in the background, to allow you (or a shell script) to continue working, include the ampersand ("&") on the end of the command.

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