8
3.0
Connecting the NH
3
CAN module
Power and CAN connections to the module are made using the Eurofast 12mm connector on the
module. The power input requirement is 12 to 30VDC at 1.5A (steady-state). At start-up, there
can be a peak current of up to 5A. Multiple modules can share the CAN bus. All modules are
configured to broadcast CAN messages at the CAN baud rate of 500K. The maximum distance
between any two nodes on the CAN bus at this baud rate is 100m. Each end of the CAN bus
must have a terminating resistor of 121 Ohms.
3.1
Application Notes
1.
Configuration software (ECM Configuration Tool) for the module is located on the CD. This
software allows the setup, configuration, monitoring, and recording of data using supported
CAN adapters.
2.
The NH
3
CAN is calibrated for NH
3
between 0 and 100ppm. The user can zero and span the
NH
3
measurement. The user zeros and spans can also be cancelled, returning to the factory
calibration. The factory calibration and the user zeros and spans are stored in a memory chip
located in the connector of the NH
3
sensor. No matter what the NH
3
sensor is plugged into, it
will read the same NH
3
value since the factory calibration, user zeros, and user spans travel
with the sensor.
3.
The main disturbance affecting the accuracy of the NH
3
is the temperature of the NH
3
sensor
body. Thus the sensor should be zero’d and span’d under thermal conditions (i.e. exhaust
pipe temperatures) close to what it will experience in service. During start-up, when the
sensor body temperature is constant, the NH
3
value output by the module can be used.
Typically, this takes 5 minutes when the sensor is in the exhaust of a running engine, as
much as 30min when hanging in free air or in a cold manifold.
4.
Do not exceed 500°C exhaust gas temperature. Short excursions up to 700°C are allowable.
5.
It is best to zero and span the NH
3
sensor in the exhaust of an engine and in comparison
to a reference NH
3
measurement. If you zero and span the NH
3
measurement in a
vessel fed by gases from tanks, you will need to heat the vessel walls to the temperature
of the exhaust pipe the sensor will be used in, and will need to include H
2
O and O
2
in
the gases in the concentration(s) the sensor will see in the exhaust of the engine.
6.
Do not extend the wires between the NH
3
sensor and the control module. You can lengthen
the power wires on the DC Power Cable (P/N: 11-01 or 11-02) but use large gauge wire and
make sure that the voltage at the power terminals of the supplied harness is at least 14 V
when the sensor is being heated. You can lengthen the CAN communication wires using
Eurofast 12mm cable. Eurofast 12mm cable was designed specifically for CAN
communication and along with additional “Tees”, allows you to easily build long and reliable
CAN networks.
7.
The NH
3
CAN broadcasts several messages on the CAN bus using the CANopen protocol.
Each message has an identifying number known as the CAN identifier (CANid). Since
multiple modules can be placed on the same CAN bus, each module on the bus also has an
identifying number known as the node identifier (NID). The allowable range for the NID is
0x01 to 0x7F. When connecting other non-ECM devices on the same CAN bus, ensure that
the following CANids are not used:
Summary of Contents for NH3CAN
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