Sale ends todayGet 30% off any course (excluding packages)

Ends in --- --- ---

Motec E816 expander wiring

Practical Motorsport Wiring - Club Level

Forum Posts



Tech Articles

Discussion and questions related to the course Practical Motorsport Wiring - Club Level

= Resolved threads


Hey guys. Excuse my very fundamental knowledge on this topic, but I have some questions. I have motec C125 Dash that is I/O unlocked. I need more I/Os even after getting it unlocked. In this case I am buying a Motec E816 expander which is something I’ve never used before. Now from the reading I have done it communicates Via CAN to the Dash Logger. The car itself does not have a CAN bus. This leads to my question… how would I connect these two together? Do I make a small can bus that is specific in between the expander and the dash? Any input would be nice and don’t be afraid to dumb it down for me. Thanks.

If they are indeed communicating via CAN, you are right and you would need to create a bus with only those 2 components. I've never worked with these devices, but here are a couple of generic points :

1. A CAN bus needs 2x 120 ohms termination resistors. No less, no more. Some component have them built in, that you can activate via software, or sometimes it's a selector switch or even a jumper that you need to solder together. Refer to the manual for how this work. You can also wire external 120 ohms resistor if the components doesn't have them.

2. All of the components of the CAN bus need to communicate at the same speed. 256kb, 512kb, 1mb... Again, it's usually selected in the software, but some components need a jumper to be soldered to choose it.

3. The 2 components will need to communicate with the same protocol, and you'll need to do a bit of configuration so both of your devices "understand" each others. Again, I have never used those MoTec devices so I can't help with that.

Here's a diagram of what it would looks like. "Controller and transceiver" are inside your devices, so you don't have to worry about that. If you can activate termination resistors inside the components, you just have to wire CAN High and CAN Low to each devices and forget about the external resistor shown there. For the physical constructions of the bus, wires have to be twisted together for EMI protection.


Hope it helps,


You make a CAN bus (a twisted pair of wires) Between the two devices following Frank's explanation. Make sure you join the high to high and low to low. Technically MoTeC specify 100 ohm, but 120 ohm works just the same.

You can use either bus on the C125 (bus 1 or bus 2), just take note of which one. These join to pins 47 (Can LO) and 54 (Can HI) of the E816.

To set the E816 up in your current dash manager setup, you go to Connections > Devices...

In the Bottom left corner there is an edit button. This is where you add the E816 device and select what CAN bus it is on. From there you will be able to setup all the inputs and outputs of the E816. Keep in mind that the E816 transmits the sensor data at 200hz on CAN, so if you need anything faster than that, you should prioritise it to the i/o on the C125.

Attached Files

Awesome guys, this is exactly what I needed thank you.

We usually reply within 12hrs (often sooner)

Need Help?

Need help choosing a course?

Experiencing website difficulties?

Or need to contact us for any other reason?