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Wheel speed input
The wheel speed input accepts TTL pulses from an encoder on a single wheel. An
encoder from a gearbox should not be used, and simulated TTL pulses (e.g. from the
CAN bus) should not be used. The timing of the wheel speed input pulses is critical and
nothing should cause any delay in the wheel speed input pulses.
The wheel speed input requires less than 0.8 V for a low pulse and more than 2.4 V for
a high pulse. Limited protection is provided on this port, however the input voltage
should not exceed 12 V.
The wheel that is used should not steer the vehicle. The RT will assume this wheel travels
straight.
Wheel speed output
The wheel speed output generates pulses in the same way as a wheel encoder would. The
configuration software can change the number of pulses per metre of travel. The output
has 0.8 V or less for a low and 2.4 V or more for a high. There is no protection on this
output, no more than 10 mA should be used on this output.
IMU sync output pulse
The IMU (inertial measurement unit) sync output pulse is a 100 Hz or 250 Hz output
pulse synchronised to the IMU sample time. The output has a duty cycle of approximately
50% and the falling edge is synchronised to the sample file of the data from the IMU.
The IMU is already synchronised to GPS time so one of the pulses each second will line
up with the 1PPS output. This allows other systems to sample based on the timing of the
RT.
Reverse polarity protection
The RT products have limited reverse polarity protection. Reversing the polarity on the
power inputs for short periods of time is unlikely to damage the product.
Causing a short circuit through the RT will damage the product. A short-circuit will be
created if the polarity is reversed and another connector has ground connected. In this
condition the ground input of the power supply will be connected to the positive power
supply; this causes a high current to flow through the circuits in the RT and it will damage
several internal components.
RT2000 products have had a formal safety test (see specifications). The safety certificate
only applies if the cables supplied are used or if the RT2000 is used with an RT-UPS. If
the fuse in the plug needs to be replaced, then it should be replaced with the Littelfuse
model specified in Table 30. If a different connector is fitted to the cable then an
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