This is a quick 'n dirty tool to send an HPGL file to a Hewlett-Packard plotter, with support for various kinds of flow control, and a couple of useful filters to make changes to the HPGL stream that is sent.
git clone https://github.com/rhalkyard/hpplot
cd hpplot
pip install .
To plot a file called plot.hpgl
to a plotter attached to /dev/ttyUSB0
at
9600 baud, overriding the pen velocity to 15.5 cm/s:
hpplot --baud-rate 9600 --velocity 15.5 /dev/ttyUSB0 plot.hpgl
On Windows, serial port names such as COM1
can be used instead.
Set the baud rate used when communicating with the plotter. Default is 9600 baud, the fastest speed supported by the HP 7470A.
Set the flow-control mode used in communication with the plotter. The appropriate escape sequences will be sent to the plotter to configure it for the selected mode.
Valid modes are:
-
query
(default) - query plotter for available buffer space before sending data -
dsrdtr
- hardware flow control using DSR control line -
rtscts
- hardware flow control using RTS control line -
xonxoff
- software flow control usingXON
/XOFF
protocol -
enqack
- software flow control usingENQ
/ACK
protocol
Note that dsrdtr
and rtscts
flow control require a suitably-wired RS232
cable, connecting pin 20 (DTR) on the plotter to DSR for dsrdtr
, or to CTS for
rtscts
.
xonxoff
flow control requires that the serial adapter's driver supports
XON
/XOFF
flow control. Some USB-serial adapters are buggy when operating in
this mode, or simply do not support it!
The query
and enqack
flow-control modes are implemented entirely within the
hpplot
tool itself, and should work on any serial interface. In practice, the
default query
mode should be fine for all uses, I just implemented the others
out of the sake of curiosity.
See the HP 7470A Interfacing and Programming Manual for details about the plotter's behavior in each flow control mode.
Flow-control block size. This value is interpreted slightly differently based on the flow control mode - see the HP 7470A Interfacing and Programming Manual for details. Default is 80 bytes, the default block size used by the HP 7470A. There shouldn't be much need to change this.
Suppress any SP
commands in the HPGL stream. This is useful when adapting
full-length pens for use in the plotter, as they will cause the mechanism to jam
if a pen-change operation is requested.
Set the pen velocity, overriding any VS
commands in the HPGL stream.
I have only tested hpplot
with a 7470A, but it should work with other HP
plotters (and clones) that use HPGL and a similar set of configuration escape
sequences.
Note that the -p
/--no-pen-select
and -v
/--velocity
options cause
hpplot
to rewrite commands in the HPGL stream. These options assume that each
HPGL command is terminated with ;
- a convention that is usually adhered to,
but not strictly required by all commands. Additionally, substrings of text
printed using the LB
command may get mis-identifed as commands to rewrite.
The arguments for the -b
/--block-size
and -v
/--velocity
arguments are
not checked for range, as their valid ranges differ for different plotter
models. Valid block sizes for the 7470A range from 1 to 255 bytes, and pen
speeds from 1 to 38.1 cm/s.