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I have a hardware device that outputs textual data via Parallel port (DB25) to a printer. What I would like to do is to consume this data into my application (preferably with a USB cable).
I've purchased an LPT2USB cable and tried some other adapters but I couldn't find the device (not really sure where to look). When connecting the device to the PC no driver is installed and no change is seen in Device manager. What am I missing here?

Yoav
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1 Answers1

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  1. About the LPT-to-USB cable

    Cables like this usually install a virtual LPT port in your computer. You should be able to find it in Device Manager. It works just like a regular LPT port.

  2. Working with the device

    Some COM/LPT devices don't register as actual devices. This way you don't have to install a driver because system isn't aware of new device being present, but if some program knows that device is present on some port and it's transmitting, then it's able to read the input. Your device probably works like this.

    To verify this theory run PuTTY (or any HyperTerminal-like program), select Serial and type LPT1 as Serial line (or whatever port is visible in Device Manager - it may for example appear as LPT7). Now comes the hard part - you have to guess connection parameters.

    Connection parameters are configured under Connection → Serial in the tree on the left. They are:

    • Speed
    • No. of data bits
    • No. of stop bits
    • Parity
    • Flow control

    You probably have to guess just the right set of parameters for the device to work correctly. There are small chances that there are few working parameter sets, but it's not very likely.

    Things that may be helpful when guessing: Google and an oscilloscope.

gronostaj
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