On 23/04/14 10:46, Mark Rogers wrote:
On 22 April 2014 21:00, steve-ALUG@hst.me.uk wrote:
On my browser, I go to google and type "Parallel printer to" and many suggestions come up, such as to: USB, Serial, Network, WIFI etc. I'm sure you can get a parallel to Serial adaptor, and then capture the serial data directly,
I get the same results when I try but all the ones I see are for connecting a parallel printer to a PC that doesn't have a parallel port, rather than for replacing the printer on a PC (or in this case a non-PC) which does. It's a common problem with search engines when the keywords you need to search for have a much more common meaning which is the reverse of what you need.
However.... what will you do with it then? You'll have a stream of ascii and printer control codes to decipher. Perhaps doable if it's Epson control codes, but probably quite hard if it's HP's PCL, or similar.
Until I see the data I don't know, but the printer itself is a simple dot matrix line printer so I'm hoping it won't be anything too complicated. (What I'm hoping to extract is the raw data rather than images of it as it would be printed.) As the device connected to the printer isn't a PC I'm hoping it's pretty basic in its outut.
Well, IIRC a /Simple/ dot matrix printer (DMP) can either print
a) simple ASCII characters c/w simple (ish) Epson style printer control codes control codes consisting of stuff like CR/LF Tab (but how many characters?) Bold Italic Form Feed and possibly stuff like Font name, font size etc. and probably a bit more esoteric stuff
b) extended printer control codes, usually manufacturer or printer specific. For this you'll need a good printer specific manual.
c) I'm not entirely sure about this, but I think some printers can be switched into a graphics mode so that for example with an 8 pin print-head, sending 255 (all bits on) would print a vertical bar, 0 would print a pixel wide space, 127 (lower bits on) would print the bottom half of a vertical bar. etc. When I last had a DMP I had to be careful when wordprocessing picking a font that the printer supported in hardware, because if I didn't, the printer would go into this graphics mode and "draw" each line in this graphics mode which was mega-slow because of the much increased amount of data, and produced poor output compared to the printer supported (and optimised) fonts.
d) some DMPs I think could support page control languages like postscript or some propitiatory HP stuff.
IMHO, /Simple/ DMPs are far from simple. Back in the day I used to have no-end of problems with them. :-(
http://www.pclviewer.com/resources/capture/index.html which sounds like it will do what you want and it's probably a lot simpler to get something off the shelf (assuming it's still available) from someone who can support it and specialises in it.
That does look close, I'll take a look in more detail at that. It looks like it'll capture an image of what would be printed rather than let me extract the data but it might be good enough and a lot simpler than rolling my own.
Alternatively try googling "Parallel Printer data capture" or "Parallel Printer Capture"
I tried similar searches before but found software for capturing the data going out of the printer port, which would be fine if the printer was attached to a PC, but it's not :-(
YMMV but that's how I found the product listed above.
Good luck!
Steve