pen plotter won't run

  • Thread starter Thread starter anhenriette
  • Start date Start date
A

anhenriette

hey folks, i got a little strange problem with a pen plotter i try to
run again after some 10 years. it is a colorpro plotter hp 7440 a.

i recon everything works quite fine, the demo version is runnig, you
could control it with the panel it has, but i can't gain any connection
to the computer.

the system is runnig under windows xp, another computer runs on 2000.

i tried to run the motors with pcnc, that didn't work, after that
sending some simple codes through dos, such like moving a pen or
printing a single line. (the commands can be seen on winline.com, it is
an easy method to test old plotters like that)

but even that doesn't work. the printer has a new serial cable, i also
tested the dataflow with a rs 232 minitester. there was some flow, but
the plotter is still calm.

can anybody help me waking him up?

merci beaucoup.

jette
 
but even that doesn't work. the printer has a new serial cable, i also
tested the dataflow with a rs 232 minitester. there was some flow, but
the plotter is still calm.

can anybody help me waking him up?
Click to expand...

There are several sorts of serial cable.
Straight and crossover for starters.
Then for each you have cables with loopbacked handshake
lines.
You also have to take into account flow control, and whether
you are going to use Xon/Xoff or hardware RTS/CTS.
Get it wrong and it just won't respond.
The minitester shows data, but not whether it is on the
right pins or whether the handshake lines are asserted
correctly.
You really need the plotters manual, and as a word of
warning, keep your hands away from the pens when
they move. Their power, accelearation, and speed of
movement is impressive. Which is why they get through
quite a few pen drive cables.
The most useful tool I found was an RS232 breakout box,
this enables you to open any or all of the RS232 lines,
and cross connect (or loopback) pins as needed,
using it's LED's on each side of the interface as a guide.
Once you have sussed the connections you can make
an adapter or special lead with the right configuration.
Some PC's won't send unless they see the right handshake
signals, like some need to see DCD (Data Carrier Detect),
and CTS (Clear To Send) before they will talk.

Once you have the hardware sorted then you need to
find or make a test file with the printer control codes in it.
Select pen, move pen, pen down, pen up, stuff.

If still stuck you either abandon it or find a Datascope,
which monitors the hanshake lines as will as putting
on a CRT the characters going each way. One way
black on white, the other inverse.
 
i tried to run the motors with pcnc, that didn't work, after that
sending some simple codes through dos, such like moving a pen or
printing a single line. (the commands can be seen on winline.com, it is
an easy method to test old plotters like that)

but even that doesn't work. the printer has a new serial cable, i also
tested the dataflow with a rs 232 minitester. there was some flow, but
the plotter is still calm.

can anybody help me waking him up?
Click to expand...

If you've got an RS232C tester then it'as likely that you've already
checked the following, but just to make sure...

What data structure is the plotter expecting and is the PC set up to
match?
eg data rate, word size, start/stop bits, parity.

What handshaking does the plotter use? Xon/XoFF, DTR/DTS? Is the serial
cable properly wired? There way too many ways to wire a serial cable. In
particular, did you wire Tx and Rx correctly at each end.

If both ends are the same, (both 9 pin or both 25 pin and same gender)
then pins 2 and 3 should be a cross over otherwise they should be straight
through. If one end is 9 pin and the other is 25 pin and the same gender
then 2 and 3 should be wired straight through, otherwise crossover.

Getting on to pins 6, 7, 20 etc, it depends on the hardware at each end.
Some might need to be linked at each end, some might need to to be wired
from end to end.

Check the plotter for DIP switches. If you have the option, set it to a
known baud rate, eg 9600, 8 bit word, 1 stop bit, no parity and Xon/Xoff
handshaking. That way you can use a minimal 3-wire cable with only Tx, Rx
and Gnd wired through. Google for RS232C wiring if you need the pinouts
for your connectors. Tx and Rx are pins 2 and 3 but could be either way
round depending on the connector being male or female, 9 pin or 25 pin.

If you can confirm it working, you might want to switch over to hardware
handshaking and a more fully wired cable, but at the speed a plotter can
handle output from the PC it's pretty much a pointless exercise.
 
....my friend used it some years ago connected with an oscilloscope.

After we got aware of the fact that maybe something with the cable is
wrong, we looked at the pins and just 3 were wired. we soldered a new
one with the instructions for the pinwiring to be seen on the online
manual at the hp site. all the parameters were checked and okay, like
parity and baud rate etc.

so actually the 25 to 9 pin cable we made with these pinconnections was
okay, but it didn't work, so we bought one to eleminate any faults

but still it is sleeping, okay i will check again everything tomorrow
and tell if i found out a mistake, but so far, thank you very much

Henriette
 
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