Blank page with X printed sent to printer several times a day

[Roland Bryant]

I've been having issues where either a blank page, or a page with just the letter X is sent to the printer (A couple of cases with double X)

Looking back at the PDFs generated, it does it anywhere from 2-6 times in a single day at seemingly random times.

I have a parallel cable between the retro printer module and a mid-90s Dell computer, Dimension XPS-P100 pentium. The module is connected to a Raspberry Pi 2 Model B. The 90s computer is usually turned off (though plugged in to power).

I'm using HP emulation mode. Previously I was using Epson mode emulation, and would had the same/similar problem, but with an @ symbol printed.

The printpcl script I have clears the raw data after converting to PDF, so I don't currently have an example of that, but I can comment that part out and attach it next time it happens.

[Roland Bryant]

An update. I was able to reproduce the blank page (not the X char), twice this afternoon with a static shock to the Centronics port. (I have one of those plastic carpet protectors in front of my desk, and it's really dry here, so I only have to touch the thing to create a shock).

Attached the raw file from that.

2024.raw

Blank page from static shock

(1 Bytes) Downloaded 519 times

[RWAP]

Hmm - how do you eliminate stray electrical signals from being seen as data?

A good question!

At the moment, I am thinking that we may need to introduce a character_threshold configuration setting, so that the software will ignore a print job which ony captures that many characters.

What do others think (no-one else has reported this issue).

[Roland Bryant]

That would be great. I know it doesn't really identify the root cause, but I don't think I have the skills to diagnose what's causing those stray signals from my PC (because I assume static doesn't totally explain the X chars, or maybe it does?). When I was looking yesterday through the PDFs that were generated, I saw one with four X chars, which seemed to be the max so far. So even configuring a very small threshold would solve it for me.

[RWAP]

This has now been added to the newly released v3.9 software