Not Enough Ports for a Dongle

Question: For serious digital printing, my applications require a dongle on my printer port for security reasons. I no longer have available printer ports and am 2 ports short. Is their anyway to piggy back in order to physically gain 2 additional printer ports? Should I just get a tower with more ports and network them together?

Answer: For anyone reading this who doesn't know what a dongle is, its a small hardware device that comes with some software. You need to plug the dongle into one of the parallel ports on the computer where you want to use the software in order for the software to work. In this way the software producer can ensure that the correct number of licences have been purchased for the software as one dongle is provided with each licence and the software will only work on a computer where the dongle is attached. This used to be much more common about ten or so years ago but is still used by some software.

Most dongles are designed as a pass through device. The dongle is attached to your parallel port and the printer is attached to the other side of the dongle. If the dongle functions correctly it should not interfere with the use of the printer. Unfortunately some dongles do interfere with printing and some don't supply the second socket into which to plug the printer.

In this case you have a number of options.

Some parallel port peripherals such as scanners have a pass through socket on them allowing a second parallel device to be plugged into this peripheral and run both of them from the same port. This doesn't always work too well but you might check whether you have such a pass through socket and if so see if you can free up a parallel port that way.

You can have up to three parallel ports on one computer. One is usually built into the motherboard and the other two can be added using plug in cards. Cards are available as either a single parallel port, one parallel port with one or more serial ports, or two parallel ports. All of the cards I have seen have jumpers allowing them to be set to either LPT1 or LPT2 but not all allow themselves to be configured as LPT3 so you will need to check that any card you get does allow that.

Another option (as you suggest) is to get a second computer and network them together. You can then transfer some devices to the parallel port(s) on the second computer and access them over the network. Note that any dongles must still be directly attached to the computer upon which the corresponding software is to be run. This is the most expensive option because you need to purchase not only a complete second computer but also two network cards and a crossover cable.

A cheaper alternative may be to replace some of the peripherals that you currently have connected to parallel ports with USB versions. You can then plug the new printer, scanner, etc into the USB sockets on your computer instead of the parallel ports freeing up the parallel ports for use with the dongle. If you don't have enough USB ports you can purchase a USB hub to increase the number of ports and if the computer doesn't have USB ports at all you can purchase a USB card that can be plugged into the computer to add them.

The real problem occurs if you already have three parallel ports on your computer all of which already have a dongle attached or you have two dongles that will only work when attached to the same port. In this case your only option may be to physically swap the dongles over depending on which program you want to run. If you need to run both together then your only option is to run the two pieces of software on different computers and network the systems together in order to share data.


This article written by Stephen Chapman, Felgall Pty Ltd.

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