Mapping a USB port to an LPT port

y2jake215

So, in the lab I'm working in, we're replacing a bunch of equipment, adding new computers, etc. I just set up a new computer, and need to attach it to a certain piece of equipment to read in some data. However, the equipment only outputs using a parallel printer port cable. The new computer has no printer port, only USB ports. I got my hands on a parallel port to USB port adapter, plugged that in, and installed the drivers. Here's where the problem comes in - the computer program that actively reads in the data only has 3 choices for which port to read from - LPT1, LPT2, and LPT3. There's no way to add any more, and this is the ONLY program which can do what I need (it's specific to the equipment).

So my question is, is there any way to get the computer to treat this USB port as "LPT1"? So that when this program looks at LPT1, it just goes to the USB port I'm using? Any help on this would be great. Thanks

Ruckus

If you go into the Device Manager you should find the USB>Parallel device listed under "Ports (COM & LPT)". If you look at the properties of it, the second tab, "Port Settings" should allow you to change the LPT number assigned to it.

y2jake215

Going to the Device Manager, under Ports (COM & LPT), the USB adapter is showing up as USB Serial Port (COM4), regardless of which USB port it's in, if that matters. I went to the properties, Port Settings tab, and there was no option to change it. Hit Advanced button, and it had a little box to switch the Port Number, but the only options were COM1 through COM256.

Is there something else I have to do to make LPTs an option? or do I just not know the difference between COM and LPT

Ruckus

y2jake215 wrote: »

Going to the Device Manager, under Ports (COM & LPT), the USB adapter is showing up as USB Serial Port (COM4), regardless of which USB port it's in, if that matters. I went to the properties, Port Settings tab, and there was no option to change it. Hit Advanced button, and it had a little box to switch the Port Number, but the only options were COM1 through COM256.

Is there something else I have to do to make LPTs an option? or do I just not know the difference between COM and LPT

Are you sure you got a USB>Parallel and not a USB>COM adapter?

Whats the make and model of the adapter?

bowen

http://www.dos2usb.com/

That might be more what you're looking for. Connect everything as normal and let the software translate from LPT to USB. Try it.

pacbowl

Yeah it sounds like you got a hold of a USB > COM/Serial adapter, not LPT/parallel.

COM is 9 pin, LPT is 25 pin.

y2jake215

Okay I'm kind of stupid, I really should've mentioned this. It's actually two adapters stuck together. One is an older looking piece without any serial number make or model, taking the parallel port and converting it to most likely a COM port (they're screwed together in such a way I can't really remove them to double check). The second adapter is a "USBGear", taking that COM and going into USB. When I plugged it in, it read it as "FT232R USB UART".

Ruckus

y2jake215 wrote: »

Okay I'm kind of stupid, I really should've mentioned this. It's actually two adapters stuck together. One is an older looking piece without any serial number make or model, taking the parallel port and converting it to most likely a COM port (they're screwed together in such a way I can't really remove them to double check). The second adapter is a "USBGear", taking that COM and going into USB. When I plugged it in, it read it as "FT232R USB UART".

Looks like you've got a USB>COM9 adapter and a a COM9 to COM25 adapter. In the olden days COM ports used to come in a 25 pin variety.

Daenris

I've worked in psych labs with old equipment like this. Honestly, the easiest solution is going to be to buy a PCI parallel port card for the computer. We've tried a number of adapters and none of them actually ended up working, because frequently the old experiment equipment doesn't actually follow the exact port protocol, and so it doesn't work well when translated over USB.

y2jake215

bowen wrote: »

http://www.dos2usb.com/

That might be more what you're looking for. Connect everything as normal and let the software translate from LPT to USB. Try it.

Just tried it. It basically does WHAT I want it to, but not in the way I need it to. Most programs and solutions for this I've found are all for people trying to print from DOS. The problem for me is I don't have a printer at the end of this cable, just some piece of equipment. DOS2USB seems to want a printer to be chosen, and there's just no printer to choose. I tried working around it and just trying to see if it could translate it, but no dice. Thanks though

pacbowl

I'm pretty sure that's not going to work. Regardless of that second adapter, the computer is still going to see it as a COM port. You need to find an LPT expansion card or a true USB > LPT adapter. In order for your program to use it, it has to show up as LPT1, 2 or 3 in the device manager.

bowen

Oh so. Okay I think I understand better.

You've got:

PC (USB) > Serial9 > Serial25 > Equipment

I don't think you can keep stepping up like that, you'll likely need to get a USB->Serial25 connector (Like this).

But if it's not a serial25 connector, you need a straight LTP connector like this:
http://www.eforcity.com/poth1284usb1.html?efprcggbadtf100927=sc+gb+poth1284usb1

y2jake215

If it's impossible to get the equipment hooked up using what we have now, I guess we might as well just get the PCI card, since I'm pretty sure that will work, and that's what our last resort was anyway. Thanks all for the help, and this can probably be locked unless someone has a hail mary to toss out.

bowen - I'll try looking around the lab to see if we've got any of those just hanging out. Thanks

bowen

That'll be your only other option. Your best bet is the card I think anyways. Good luck.

Daenris

bowen wrote: »

But if it's not a serial25 connector, you need a straight LTP connector like this:
http://www.eforcity.com/poth1284usb1.html?efprcggbadtf100927=sc+gb+poth1284usb1

Actually that's for connecting directly to a printer, so it's not a standard parallel port connector, it's the 36-pin centronics connector that's found on parallel printers.

You'd actually want something more like this:

http://www.eforcity.com/poth1284usb2.html?int=efsechtxtrigos-item

But as I've said, I've tried a number of USB->Parallel adapters that didn't work because they're made specifically to work with printers, and a lot of the data collection hardware doesn't work exactly the same as a parallel printer.

Since you have to but something anyway, just go with a Parallel Port expansion card, which will be almost guaranteed to work. Something like this: http://www.cdw.com/shop/products/default.aspx?EDC=1688697#TS if you need PCI express, of if you have regular PCI this: http://www.cdw.com/shop/products/default.aspx?EDC=520866#TS

baudattitude

To get geeky, because I used to work on hardware like this:

Parallel ports were originally designed for output only, so you couldn't really read data back from them. On the other hand, they have five "status" lines used to indicate various printer states.

Then people realized that if you split bytes into nybbles - I'm not making that word up - at the device level, and sent it back to the computer four bits at a time, your "output-only" port became an input port as well, and in an age when PCs generally had two serial ports, one taken by a mouse and the other by a modem, getting more use out of the parallel ports was a godsend.

Later on, companies started making actual bidirectional parallel ports, but honestly I don't know much about those because I'd moved out of hardware.

Anyway, what I'm getting at is that any device sending data to a PC over a parallel port is using something that was a bit of a hack back in the day and probably isn't supported by USB-parallel adapters.

darkgrue

baudattitude wrote: »

Anyway, what I'm getting at is that any device sending data to a PC over a parallel port is using something that was a bit of a hack back in the day and probably isn't supported by USB-parallel adapters.

Depends on the implementation. True Bi-directional USB-parallel adapters exist, if a quick search on Google is any judge. Here's an example: TRUE-Bi Directional USB Printer Adapter. It's $35, that doesn't seem so bad, especially if it does what you need (which... you probably won't know until you try it, but it looks like it would have a good chance). An adapter that works with fussy printer drivers might be just the thing, since those drivers might very well pull the same sorts of hardware addressing stunts that your data collection software does.

There's probably lots of USB adapters that don't implement bi-directional parallel, not because the technique is too old/too new, it's because the manufacturer was lazy and didn't implement it. USB is plenty capable of shuffling the data both ways.

And, as other people have mentioned, if what you need is a parallel port, a serial port with or without 25 pins isn't the same thing, no matter how many adapters or gender-changers you put on it. It sounds like you have a USB to serial adapter, and that just won't do.

DrFrylock

darkgrue wrote: »

And, as other people have mentioned, if what you need is a parallel port, a serial port with or without 25 pins isn't the same thing, no matter how many adapters or gender-changers you put on it. It sounds like you have a USB to serial adapter, and that just won't do.

Parallel and serial ports are fundamentally different, and there's no adapter from one to the other that's going to work for you. You need to figure out if your device is really hooking up through a parallel port or a serial port. Most serial ports are 9-pin (DB9) but some used to be 25-pin (DB25) in the bad old days. Parallel ports are DB25 also, but the opposite gender so you don't accidentally plug one into the other.

Ruckus

DrFrylock wrote: »

darkgrue wrote: »

And, as other people have mentioned, if what you need is a parallel port, a serial port with or without 25 pins isn't the same thing, no matter how many adapters or gender-changers you put on it. It sounds like you have a USB to serial adapter, and that just won't do.

Parallel and serial ports are fundamentally different, and there's no adapter from one to the other that's going to work for you. You need to figure out if your device is really hooking up through a parallel port or a serial port. Most serial ports are 9-pin (DB9) but some used to be 25-pin (DB25) in the bad old days. Parallel ports are DB25 also, but the opposite gender so you don't accidentally plug one into the other.

I'd say if the software he has for the device is requesting an LPT1, 2 or 3, it most likely requires an ECP compatible LPT port.

justpassingby

y2jake215 wrote: »

So, in the lab I'm working in, we're replacing a bunch of equipment, adding new computers, etc. I just set up a new computer, and need to attach it to a certain piece of equipment to read in some data. However, the equipment only outputs using a parallel printer port cable. The new computer has no printer port, only USB ports. I got my hands on a parallel port to USB port adapter, plugged that in, and installed the drivers. Here's where the problem comes in - the computer program that actively reads in the data only has 3 choices for which port to read from - LPT1, LPT2, and LPT3. There's no way to add any more, and this is the ONLY program which can do what I need (it's specific to the equipment).

So my question is, is there any way to get the computer to treat this USB port as "LPT1"? So that when this program looks at LPT1, it just goes to the USB port I'm using? Any help on this would be great. Thanks

justpassingby

Hi, I was just browsing around and saw your question. I noticed it was logged in 2010, if you have not come right yet, let me know. I have an easy method that will work.