DMA for LPT port

Dave Hardenbrook · Guest

I had this issue (I may have posted about it before) with a client with
a HP OfficeJet All-In-One using LPT1. She could print but not scan, and
even when she printed, she got the message, "Communication Test Failed",
& when I looked at the port settings for LPT1, "Enable bi-directional"
was grayed out. My sleuthing had led me to conclude that there is an
issue with Printer-to-PC data flow, but addressing the problem further
has been difficult because she won't let me take the printer to test it
on another system.

What I did do is go into BIOS to verify that ECP was enabled (it was),
and then, in what I have to admit was a wild grasp at straws, I changed
the DMA from channel 3 to channel 1. Lo and behold, scanning now works!

What I don't understand is WHY changing the DMA worked -- As I say, I
was just trying anything at that point. Can anyone cast some light on
this? My other concern is that even though scanning now works, the
"Communication Test Failed", error still comes up when anything is
printed, and "Enable bi-directional" is still grayed out. So I'm
concerned that the problem isn't really solved and that the scanning
issues will recur.

Any thoughts?

Dave

NitsBits · Guest

smackedass · Guest

Dave,

While I admire your concern and curiosity as to why this worked, every once
in a while you've got to say to yourself:

"All's well that ends"

The chances of you ever running into this problem again are miniscule. File
this away, on paper, in the event that this ever does rear its head, you'll
remember what to do.

Who ever uses parallel ports these days, anyway? The problem could have
been just as easily solved by going USB. Not to diminish your efforts, I
would have done the same thing that you would have done, and then probably
have asked the same question, but hey, there's something to be said for
following the path of least resistance.

smackedass