Sevcon Gen4, Applications Reference Manual, Page: 105 / 123

Configuration
Doc. # 177/52701
Rev. 3.3
6-35
To prevent vehicle roll away on inclines, the electro-mechanical brake normally does not release
until the traction motor(s) are producing torque. This feature can be disabled using 2903
h
,3.
External LED
This mirrors the operation of the controller’s on board diagnostic LED. The external LED object
2401
h
can be mapped to an analogue output to drive a lamp on a vehicle dashboard.
Alarm buzzer
The alarm buzzer object (2402
h
) must be mapped to an analogue output.
Configure the alarm buzzer output, if required, to be activated by one or more of these
conditions at 2840
h
:

forward motion or forward direction selected

reverse motion or reverse direction selected

faults other than information faults

controlled roll-off

BDI low.
A different cadence for each of the above conditions can be configured.
Brake Lights
A brake light output object is available (2404
h
) and can be mapped to an analogue output. The
brake lights will illuminate whenever the footbrake is pressed (providing either an analogue or
digital footbrake input is available) or the system is in direction change braking.
Horn
Ensure a digital input switch is mapped to the horn switch object (2101
h
) and an analogue output
is mapped to the horn object (2403
h
).
Vehicle Speed Calculation
The controller can be configured to calculate vehicle speed from motor speed by setting a
configurable ratio between these values in object 2915
h
.Calculated vehicle speed can then be
transmitted to the CANbus for use with compatible displays, or used to keep a log of total
distance travelled by the vehicle.
The convention is to calculate vehicle speed as a signed number in 12.4 format in kph. This is
required for compatibility with ClearView displays and the odometer. In case a custom display is
used whose units are different, a user speed calculation is also provided whose units are
independent from all other features.
Two sets of ratios are provided for calculation of a vehicle and user speeds, located in object
0x2915. While vehicle speed is a signed value, the option to have unsigned user speeds is also
provided (an absolute value will be calculated).
The ratio between motor speed and vehicle speed will be dependent on vehicle drive train
parameters such as gearbox ratio and wheel size. However, the ratio should be calculated such
than when it is multiplied by motor speed (which is in rpm), the result is vehicle speed in kph
12.4 format. To do this, the following equation can be used:

Set the divisor (object 2915
h
sub index 2) to a known speed point of the motor