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bort · Newbie Joined: 23 Nov 2004 Posts: 3

I'm trying to write an application that sends a reset instruction to a printer. the application will run on a windows 2000 computer, the printer is connected to LPT1 via a parallel cable.
Now, interfacing parallel ports really is a terra incognita for me, but after having done some reading I think I know what I'm supposed to do, i.e. send a signal through pin 16, the second bit in register base + 2, the control register. I'm using vds.dll and UserPort to communicate with the port, but my printer does not react in any way to what I'm doing.
this is what I send to vdsdll:

Skit3000 · Posted: Tue Nov 23, 2004 1:39 pm Post subject:

Hi Bert, welcome to VDSWORLD... Smile

Could it be possible that your printer uses a different instruction set then "normal" printers? Maybe you should look what instruction your computer itself sends to your printer to reset it?

Btw. I added the [code] and [/code] tag to your post. With these tags, you can convert code into highlited code on this forum... Smile

bort · Newbie Joined: 23 Nov 2004 Posts: 3

define "normal" printers? it's a HP LaserJet 6P.
I don't know how to reset the printer from my computer, I can cancel all documents, but isn't that just for documents in the print queue? when I use the cancel function in my driver control panel, I don't see any traffic over the parallel port.
the reason why I need to reset is: I need to clear the printer's buffer to remove any uncompleted documents before sending another document to the printer.
thanks for the reply.

jules · Posted: Tue Nov 23, 2004 1:52 pm Post subject:

I don't know anything about VDs DLL, but when I last wrote some software to interface with I/O ports, it didn't work under NT operating systems, because Windows doesn't allow direct port access. You need to install a special driver. I seem to recall that I used the DriverLinx Port I/O driver, from http://www.driverlinx.com/DownLoad/DlPortIO.htm. I also seem to recall that I had to rewrite my code so that it called routines in the driver DLL to talk to the port. It was a long time ago, and I don't have a copy of the code any more.

jules · Posted: Tue Nov 23, 2004 1:56 pm Post subject:

Having seen what you are trying to do, I think you are going to have a problem. Even if you use the driver as I suggested, I think there is going to be a problem because your driver and the printer driver are going to be fighting over the printer port. NT is not like 9x where anything can write to a port regardless of what else is using it.
I think you have to try to find out if there is a way to tell the printer driver to reset the printer.

Skit3000 · Posted: Tue Nov 23, 2004 1:56 pm Post subject:

Well, with "normal" printers I ment printers which are using commands which are specified in protocols. A lot of printers do not, that's why they often need special drivers to run. Maybe you can contact HP if they have some schemes lying around which you can use to see if you are sending the right instruction? Smile

bort · Newbie Joined: 23 Nov 2004 Posts: 3

that's what UserPort is for, to allow port access in W2k. I do have access to the port, that does not seem to be the problem.