serial plotter on usb to serial converter problem

  • Thread starter Thread starter bigbear
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bigbear

When connected to an old laptop with a serial port the Houston Instruments
DMP 60 series pen plotter works fine. A newer laptop without a serial port
but hooked thru a usb to serial converter (tried 2 different makes),
communicates with the plotter but plots a lot of garbage lines!

Anyone know what can be causing this and if there is any fix?

bigbear
 
When connected to an old laptop with a serial port the Houston Instruments
DMP 60 series pen plotter works fine. A newer laptop without a serial port
but hooked thru a usb to serial converter (tried 2 different makes),
communicates with the plotter but plots a lot of garbage lines!

Anyone know what can be causing this and if there is any fix?

bigbear
Click to expand...

There is some advice at the bottom of this page. Basically,
consider whether flow control or communications rates have
to be configured, to make it work properly.

http://www.bratlady.com/HI_plotter.shtml

Paul
 
Thanks Paul but the driver is not the problem. I've been using the HPGL
Draftsmaster1 driver which works fine with the HI plotter. It's only when I
use a usb to serial adapter instead of a direct serial port that things blow
up. I am wondering if it's something about the the converter which prevents
all plotters from working or perhaps there is some setup that needs to be
changed to make it work.

bigbear
 
Thanks Paul but the driver is not the problem. I've been using the HPGL
Draftsmaster1 driver which works fine with the HI plotter. It's only when I
use a usb to serial adapter instead of a direct serial port that things blow
up. I am wondering if it's something about the the converter which prevents
all plotters from working or perhaps there is some setup that needs to be
changed to make it work.

bigbear
Click to expand...

I specifically mentioned "flow control", as it is a configuration
option of a serial port. The same applies to setting the
baud rate, start/stop bits, 8 bit data and so on.

Flow control can be done a couple of ways. There are status signals
on the RS-232 side that are used for flow control at the hardware
level. There is also XON/XOFF method. I would investigate
whether there are any differences between a standard RS-232
interface, and the USB adapter, with regard to settings like that.

Do you have any information on the protocol used by the plotter ?
Have you considered using Hyperterminal, to talk to the plotter
via the USB to serial interface ? If you were debugging a modem
for example, you could send the "AT" command and look for "OK"
to come back, in a terminal session with the device. Perhaps if you
know something of the protocols and supported commands, you can
use that information, and Hyperterminal, to debug the USB
serial port.

Paul
 
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