Plex SDM-330 Display

In 2025 I replaced the trustworthy RaceTechnology Dash4Pro with a Plex SDM-330 colour display. The main reason was to allow me to replace the CAN-Switch board, that was providing two rotary switches and two paddles to the ECU, since the Plex display had many more digital and analogue inputs. This meant I could have four rotary switches, as well as two paddles, and send the data instantaneously to the ECU over CAN.

This excellent article was written by the team at Plex, and features the SDM-330 and the approach I took to installing it on to the steering wheel.

I've ended up with a crystal clear, easy to read in daylight, versatile and great looking colour display, and full CAN functionality from the paddles and rotary switches on the steering wheel, which is exactly what I wanted to achieve. The technical support from Plex is fantastic, though I did find difficulty finding the answers on line, an email usually elicited a quick and accurate response from the support team.
Below are some notes about the installation.

It turned out to be a very trivial change to get the ECU to recognise the data sent from the Plex dashboard. It was as I thought, that it needed a full 8 bytes of B Frame data, otherwise the frame would be discarded. With the Plex configured to send four rotary switches, plus the two digital paddles, and two more fixed values to pad the frame out to 8 bytes, I simply had to reassign the ECU IO to the relevant B Frames and it worked! Both paddles are recognised, along with all four switches. I also changed the Plex to send 0 to 11 for the 12 positions provided by the rotary switches, rather than 1 to 12, and the ECU recognised all the switch positions.

I also unassigned the pair of analogue inputs on the SLAVE1 AN channels, which means I now have another pair of free analogue inputs available (via the X10 expander) which could be used elsewhere to monitor more of the engine health.









The printed bezel will be available in the Ebay shop, so if anyone else wants to use the same solution, I'm happy to manufacture and supply the parts.

Mk3 printed Plex dash bezel

The final version of the printed bezel was waiting for me when I got home on Thursday, so I didnt waste any time in taking the steering wheel apart and fitting the quick release boss and other parts to the new wheel. I think it looks great. I've just got a few wires to fit and it can be plugged in to the car for testing :D
Link to the Youtube short.



This is the schematic for the wiring that I need to produce to connect the four rotary switches, the joystick, and the paddles, to the Plex connector.

Dashboard housing update

I've made a final push to get the dashboard housing completed, by mirroring the chamber I added on the side for the wires, so there is now a chamber on both sides of the housing. This will give me more capacity for wires to run down to the front panel for the switches. I drilled the steering wheel at the weekend, for the Plex dash to attach to it, and the dash fits nicely inside the housing, against the aluminium wheel centre.

Plex dashboard sending data over CAN video

Yet more time spent on the Plex dash, trying to get it to do what I want. I've worked out how to convert kph to mph, using a math channel, and I can now get it to switch screens according to a User Flag that I've set. I like the whole User Flag concept thing. It allows you to set the flag to True or False based on the value of the channel. Its a neat way of managing whats displayed on the dash.

I've got one setup called Racing, which is True when the vehicleSpeed is over 22kph, and one called Pits which is True when the vehicleSpeed is below 21kph.

If you have a channel coming over CAN which is in KPH, its very easy to convert to MPH, in fact, you dont even need to convert it. The Plex software allows you to select MPH with a Numeric control, and it automatically shows it in Miles Per Hour. Nice.

The splash screen is also working, it is another tricky feature to work out. It says it will support JPG or PNG, but I havent managed to get JPG to load, PNG seems to be ok, but even then on one attempt when the image was set to load on bootup, the image caused the display to show garbage for a second instead of the picture I'd uploaded. With PNG, background transparency is supported, and it works too.