Interfacing a USB Parallel port

please help ,i use matlab with my laptop which doesn,t have lpt port ,i got usb 2 lpt cable(db25 connector) but windows recognise it as “usb printer support ” not as ordinary lpt port,matlab didn't recognise any lpt port

[Priyanka]

Hi, I am facing the same problem. I bought 25pin D sub to USB cable from amazon to control RF attenuator with parallel programming. Did any one find the solution for this? Is the fault in the cable? or I need to look for some Drivers?

[Walter Roberson]

@Priyanka

It might be a cable problem.

There are two major styles of parallel port cables. One of the styles contains minimal control logic, basically just enough to drive the data pin and the timing pin. The other style is more expensive and contains full logic control and supports pins such as BUSY, LINEFEED and SELECT.

USB communications does not map 1 to 1 to pins, so to get the full operation there needs to be control logic that interprets USB data and maps it into pin operation -- which requires that operations go through drivers to encode state into data, and tear-down logic to decode data back into pins. Whereas for the minimal cable, data maps pretty directly into pins and normal USB-over-serial drivers do the trick.

If your RF attenuator only requires data pin output and STROBE then most any cable would be expected to work.

[Priyanka]

Hi Walter, Thank you for your response, It was helpful. I have minicircuit ZX36-31a-pps+ attenuator ( https://www.minicircuits.com/appdoc/AN70-004.html ) with its cable that has 25 pin D sub adaptor to interface with PC. Since, my Laptop does not have this port, I bought parallel port to USB convertor. It make sense with what you said. I havnt work with such device before requiring 6 bit data to control its state. The software provided by minicircuit does not identify device connection either. I am planing to give control signal with arduino now. I guess that would be easier. Thanks

[Walter Roberson]

Are you able to run the "Mini-Circuits" digital attenuator control program to configure the parallel port address?

Answer 1

[Walter Roberson]

I believe that I have read that this is a matter of having used the incorrect cable. There are two different possible cables to connect to parallel ports, and I gather that some companies are not very careful about their labeling.