cannot get usb to LPT adaptor to work.

[haklesup]

My experience with USB to LPT adapters is they generally don't work. They may work for some legacy unidirectional printing modes (like a dot matrix or daisy wheel) but most bidirectional modes (like ECP) are nearly impossible to get working and if you do get it to work, the device may operate extremely slow.

This is because USB is very good at sending large packets of data all at once serially but once you try sending smaller packets of data and stopping to read in between writes all sorts of overhead is added to each data transaction and things either crawl or timeout or simply dosen't respond. There are all sorts of places data can bottleneck in the serial to parallel translation but mainly it's the USB's need to check 256 (usually empty) ports on the hub before servicing the one you are using each time you initiate another data transfer. This costs ms per data transaction and adds up fast. There are modes called isosynchronus that handle smaller packets of data better but you generally need a device specific driver to enable it and the generic LPT driver you get most likly does not support any fancy modes.

I have an instrument we are making a USB interface for that has a parallel structure not unlike a printer inside. We have had to write all sorts of firmware for the USB controller to get things to work and avoid numerous data bottlenecks. I ran into similar data bottlenecks when we tried a PCI to ISA adapter (motherboard slot). At least PCI suppoted some parallel data streams, PCIe is as serial as USB at its roots.

[Bear]

dacflyer...When I first put my HP Laserjet 5P printer on my new computer I bought a usb to parallel cable. I was told that it was plug & play. I was not told that I had to go into Win 7 and change the port from LPT1 to USB001. I did this by going into printer properties and selecting "customize your printer". I do not know if your OS (98se or XP) has this option or not.
When I first hooked up the printer Win 7 recognized it as the correct printer but I could not use it until I changed the port from LPT1 to "virtual port for usb 001".

Hope this might help.

Dennis

[CeaSaR]

Yeah, that darn USB00* designation was a pain because it is dynamic. On the network I detailed before,
we had problems with the USB devices changing numbers (001, 002, 003, etc.). Had to go in, delete the printer
and re-install it. All depended on what was started 1st as to what got assigned where. Sometimes it got
screwed up due to MS-Updates that futzed with stuff. Didn't take long to fix, but it was annoying.

CeaSaR

[dacflyer]

i did select the usb option in my printer settings, still no luck.
i sort of gave up..
i started looking at a wireless device that turns printer into a wireless device, from what i understand it works with my wireless router, and my laptop.
i wonder how complicated it will be..
D-Link makes the device. attaches tight to the printer.
model - DP-311P Wireless Print Server
anything i should look out for as far complications ?

[Ed446]

Tiger Direct has a Sabrent cable item# M501-1058. I think it is now own sale for $8.00. There are 280 reviews for this cable. Some good some bad. Some that did not work out of the box tell what they did to get it working.
Edwin

[dacflyer]

thanks for the tip... i'll have a look...

[dacflyer]

update - back when i was playing with this adapter i had the printer cable connected between.
someone said that the cable might not work for some reason, and that i should connect the adapter directly to the printer... problem is my adapter is a 25 pin type, and i need the other type ( i do not know the name of it )
it is common to many printers.. does anyone make such an adapter, if so what is it called ?
and why would my regular printer cable not work ?

[CeaSaR]

update - back when i was playing with this adapter i had the printer cable connected between.
someone said that the cable might not work for some reason, and that i should connect the adapter directly to the printer... problem is my adapter is a 25 pin type, and i need the other type ( i do not know the name of it )
it is common to many printers.. does anyone make such an adapter, if so what is it called ?
and why would my regular printer cable not work ?

Parallel printer cables were usually DB25 to Centronics. Try looking at the usual computer "shops"
such as Newegg or Tiger Direct, then try the usual electronics suppliers, but make sure you give
MCM Electronics a look. They ususally have the oddball or old school thing you need.

As for why the cable wouldn't work, could be that the USB port couldn't supply enough juice to
power a long run (over 6') at standard old printer levels - mixture of 5V and 12V.

CeaSaR

[dacflyer]

Hmmm, i think my cord is about 6ft too.
i'll try to find the adapter, and see what happens.
i did not know that there was a mix of 5 and 12 volts going thru the printer..
if that's the case then it's hard to believe how the usb adapter ever could work, unless it has a inverter built in.

[Lenp]

I have DB-25 / Centronics printer cables collecting dust. Pay the freight and I'll send a couple!
Len

[Ed446]

I recently installed an HP 1100 printer using about a 6 foot adapter cable parallel printer to USB. The operating system Windows 32 bit professional. The computer went to the internet to find the driver for USB and also found the software for the printer. If the cable is moved to another USB port, windows thinks it has found a new device.
Edwin

[CeaSaR]

I recently installed an HP 1100 printer using about a 6 foot adapter cable parallel printer to USB. The operating system Windows 32 bit professional. The computer went to the internet to find the driver for USB and also found the software for the printer. If the cable is moved to another USB port, windows thinks it has found a new device.
Edwin

Yeah, it'll do that every time you change the designator (USB001, USB002, etc.) if it was never
installed on that particular "one". Good thing is, once the driver is downloaded, initially, the install
is much more quick - no internet search needed.
So, you should either:
1) Keep the USB device plugged in and in the same slot
2) Take the few minutes and install it on every slot
to make sure it works all the time. This is no guarantee as "Winders" has a mind of its own during
the cold startup procedure.

CeaSaR

[dacflyer]

lenp... i'll send you a PM and we will go from there...

[Lenp]

Dacflyer
Here is the Centronics pinout http://www.lammertbies.nl/comm/cable/parallel.html
Some printers just do not work with anything other than a legacy parallel port. The Canon Image Class copiers, with a parallel port, are classic problems. They need a special and expensive adapter to use on USB or a network. Other printers may not be so picky.
Len