MoTeC SDC3 - Manual (Page 7)

MoTeC SDC3 5 Functionality
Speed Measurement
The SDC3 can be configured to use one of two different methods to measure wheel speeds:
ABS CAN (Default method)
Four wheel speeds are detected by the ABS unit and transmitted over the CAN bus to the SDC3. This is
the method used by the factory DCCD controller and requires no modification of the wiring. Individual wheel
speeds can be enabled or disabled and the speed calibration can be adjusted for different wheel sizes and
sensor teeth.
Wheel Speed Sensors
Up to four wheel speed sensors may be wired directly to the SDC3 connector by modifying the vehicle
wiring. The wheel speed inputs can be configured as hall effect or magnetic sensors with adjustable
thresholds, and individual sensors can be enabled or disabled. The speed calibration can be adjusted for
different wheel sizes and sensor teeth. Magnetic sensor input thresholds are individually configurable for
front and rear sensor pairs according to the current front and rear speeds.
Front, rear and vehicle speeds are calculated from the wheel speeds, and all speeds are transmitted in CAN
messages for logging by the ADL (Advanced Dash Logger).
Front speed, rear speed and vehicle speed are also transmitted over CAN in a format that can be received by the
MoTeC M800 ECU. The MoTeC WRX V910 OEM ECU (if fitted) can be configured to log these wheel speeds or
use them in engine control strategies.
For information on configuring speed inputs, see Setup | Input Setup in the SDC Manager section.
Speed Calculations
The method of calculating front, rear and vehicle speeds is dependent on the status of the brake input.
When the foot brake is applied, speeds are calculated as follows:
• Front Speed is the faster of the two front wheel speeds.
• Rear speed is the faster of the two rear wheel speeds.
• Vehicle speed is the faster of the calculated front speed and rear speed.
When the foot brake is not applied, speeds are calculated as follows:
• The front speed is the average of the two front wheel speeds, weighted 80% towards the slowest front
wheel speed. If one front wheel speed is less than half of the other front wheel speed, then front speed is
simply the faster of the two front wheel speeds.
• The rear speed is the average of the two rear wheel speeds, weighted 80% towards the slowest rear
wheel speed. If one rear wheel speed is less than half of the other rear wheel speed, then rear speed is
simply the faster of the two rear wheel speeds.
• The vehicle speed is the average of the front and rear speeds, weighted 80% towards the slowest speed.
If either the front or rear speed is less than half of the other speed, then vehicle speed is simply the faster
out of the front speed and rear speed.
If any wheel speed exceeds 300km/h, the sensor reading is ignored until its speed returns to below 300km/h for 2
seconds. This is to prevent erratic behaviour from noisy wiring or faulty sensors.
Brake Status
The SDC3 can be configured to use one of two different methods to measure brake pedal and hand brake status:
CAN Status (Default method)
The brake pedal switch is wired directly to the ABS unit and the hand brake switch is wired directly to the
body integrated unit (body computer). This is the method used by the factory DCCD controller and requires
no modification of the wiring.
Direct Wired Switches
The brake pedal and hand brake switches may be wired directly to the SDC3 connector by modifying the
vehicle wiring.