Flat-Bed Pen Plotter - Roland DPX-3300

• A1 size bed.
• 8 pens.
• Serial (RS-232) and parallel interfaces with USB converter.
• Made in about 1987.
• Electrostatic paper hold-down.
• Good pens for it are “Staedtler 323 Triplus Colour Fibre” and “Pilot V-Ball” (0.5 or 0.7) but they need adapters. There should be some adaptors in a box on the plotter.
• Operation Manual
• Service Manual
• Large list of useful links and resources

The serial→USB converter is based on an FTDI chip. Depending on your system, you might need a driver for this, which can be downloaded from https://ftdichip.com/drivers/vcp-drivers/. Installation instructions can be found at https://ftdichip.com/document/installation-guides/. The following is a quick version based on our testing.

Once you connect the USB cable, Windows should automatically install the drivers, provided you have internet.

To confirm this, you can open Device Manager (search for it in the Start menu). You should see a “USB Serial Controller” under “Universal Serial Bus controllers”, and a “USB Serial Port (COM3)” under “Ports (COM & LPT)”. You might see a different COM number, such as COM5. You can also find the COM number by opening the command prompt and typing mode. Take note of the number.

The PC near the plotter should normally have it connected at COM3.

If for some reason the device does not show up in Device Manager, try installing the drivers for your Windows and architecture from the above link.

Included in the kernel on most distros, tested on Ubuntu 22.

Upon connecting, you should be able to find the device by running the following on your terminal:

ls -al /dev | grep ttyUSB

Normally it would show up as ttyUSB0 (unless you have other devices attached). To confirm, you can unplug the device, run the command, plug it back in, and run the command again. A new device that popped up would be it. Take note of the group that owns the device, usually it would be dialout. Make sure that your user is in that group. You can do so by running:

groups  # see the groups your user is in
adduser myuser dialout  # add myuser to the dialout group

You might need to log out and log back in for the changes to take effect.

You can also run any of the following commands to find out more about the aliases or the device itself:

ls /dev/serial/by-id
ls /dev/serial/by-path
dmesg | grep FTDI

If you want to use the plotter with Inkscape, you will also need to install the pyserial Python package. We installed this by running:

sudo apt install python3-serial

You might be able to install it via other package managers (either system-wide, with pip install —-user, with uv, or other means, untested).

When exporting via Inkscape, you might encounter an error from pyserial being unable to open or write to the device. Make sure that your user is in the dialout group (or whatever group that owns the plotter's tty device).

Download the driver from https://ftdichip.com/drivers/vcp-drivers/.

We tested it on MacBook Pro M1 Pro 2021 and MacBook Air M3, so we downloaded the .dmg file for ARM (though both links seem to just be a zipped .app). Unzip it and put the .app file into the Applications folder, then open it and click Install. You might have to accept some security popups, and it might ask you to go to Settings > Login Items & Extensions > Background App Activity, and enable the driver in there.

Once installed, connect the device and run the following command in the Terminal:

ls /dev | grep cu

You should see the device as something like /dev/cu.usbserial-5 and/or the chip name such as /dev/cu.usbserial-XXXXX. Either one should work fine. It might also show up with the tty. prefix, so you can find it with:

ls /dev | grep tty

You can send images to the plotter from Inkscape.

First, make sure everything you want to plot is converted to a path by highlighting each thing in turn and selecting “Path > Object to path”. This should work with most vector images and text.

With any raster images, you'll need to process them into a vector before plotting.

Text will vectorise into an inner and outer outline, instead of a simple centreline. “Centerline” or “plotter” fonts are available via Extensions → Text → Hershey Text You can make your own custom font for Hershey Text with this extension - please note this involves hours of faff!

SAVE YOUR WORK. The plotter extension seems quite crash-y, so make sure to save your work before trying to plot it.

Connect your computer to the plotter if not already.

Find out the serial port of the plotter. This is the COM number on Windows (e.g. COM3) or the device path (e.g. /dev/ttyUSB0 or /dev/cu.usbserial-5) on Linux and macOS.

In Inkscape, go to Extensions > Export > Plot

Enter the settings as in this image:

Note particularly that Serial Flow Control MUST be hardware. Without this, you may get partial plots, but you'll get errors in them.

Hit apply to start. It may take a little time (up to a minute or two) for it to start plotting.

The origin point is in the center of the plotter.

By default, Inkscape will locate the bottom left-hand corner of your plot at the origin (that is, the bottom left-hand corner of the things to actually plot, not the inkscape document). There is a check box 'center origin' on the Inkscape plot plugin popup. If you check this the center of your plot will be located at the center of the plotter.

To set up a plot consistently on standard paper sizes, use the template files that contain guides for A2, A3, and A4 papers.

The templates can also be found in the computer beside the plotter (WPC35) and subtle guide markers found on the plotter surface. They are are stored in “/Documents/plotter” and are named “plotter_A2_guide”, “plotter_A3_guide” and “plotter_A4_guide”. Create a copy of the template you want to use, paste it in your own folder, then load this file in Inkscape.

The template file contains two corner paths that force the plotter to draw exactly about the origin. The corner paths match up exactly with those drawn on the plotter surface already; to avoid drawing them again to your page, place an empty pen holder in pen slot 8 on the plotter. If nothing is in slot 8, the plotter will fall back to slot 7, then 6, and so on, until it finds a pen holder to draw with. With an empty pen holder, the plotter won't draw any extra markings, just your design wherever you've placed it on the page.

When you are ready to plot, add your paper to the plotter surface, aligned with the corner guides drawn in black ink on the plotter surface. There are two corner guides for each page size, lower left and top right, expanding out from the center of the plotter.

It's easier to see the markers looking at the plotter surface from an angle and with a light shining on them.

If you stop a plot mid-way (e.g. by killing inkscape and turning off the plotter), the serial adaptor can still hold some of the plot in its buffer, so make sure you turn off the plotter AND unplug the adaptor from your computer to kill power to the serial adaptor to purge this.

The Inkscape plot dialogue will freeze until either the plot completes or the serial adapter is removed from the computer.

MacOS often glitches when sending data to the plotter from Inkscape, overrunning its print buffer. If printing instructions to the serial buffer of the plotter directly, add a small pause between instructions so as not to overwhelm the plotter.

There are some 3D printed pen holders in the box. Note that not all of these work and they can be a bit finikey.

For the plotter to pick up a pen, it has to detect a pen in the appropriate slot. There's a small microswitch that the pen had to depress. If it doesn't the plotter will pick the next available pen. You can check the pens are working before starting your plot by using the pen select buttons on the plotter. If you can press the appropriate button and the plotter picks up your pen, then the pen holder is being properly detected and it will work properly when you start your plot.

An adapter for Staedler Triplus pens is available here. It is compatible with normal thickness (1.0 mm) and fineliner (0.3 mm) models but not the mechanical pencil.

Print settings are in the linked model description.

A generic CAD model for the pen holders can be found here on Onshape. You can open the “Configuration Panel” on the right hand side (second icon down, looks like a white cube with a table on its top left) and choose different pen sizes (right click a row and select “switch to” and the model will update). You can then right-click on the model and “export” to get an STL ready for slicing and 3D printing.

If you create a free Onshape account you can “copy” the CAD file so you can create your own branch and edit it to add more configuration sizes/correct errors in the model. Update the link above with your improved version.

The default pen force seems to be tuned to felt-tip pens but there may be some variance if the “Auto” light is on - the plotter has an “Pen Type Discrimination Function” that amends speed and force settings based on pen colours. More detail on page 3-8 of the manual. For Gel pens, you need more force. You can change the force mid-plot by pausing it, holding down Fast / Pen Force and selecting the pen force you want. Pen force can also be set up in the export plot dialogue but this may be ingored..

Git repository of useful HPGL-generating software, in C for Linux:

http://github.com/anachrocomputer/vec