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7 General communication functions overview
Triton OMD CAN protocol / Rev.-No. 03 19
7 General communication functions overview
7.1 Actual sensor number verification
7.1.1 Network connection healthy scenario
Communication in the network starts with verification of preset number of OMD sensors in
the network, which is configured with parameter 200 OMDSensorUnitsNumber .
Sensor number verification procedure is initiated by the master device (evaluator) by means
of common designated service message
kSensNumDirectCountCommand
, sent via CAN1 and
CAN2.
Data item within this message:
• Running sensor counter (is equal to 0 in masters tx-message);
• CAN channel Tag (0 - for CAN1 and 1 – for CAN2 in masters tx-message).
On receipt of
kSensNumDirectCountCommand
each sensor increments the running sensor
counter data item and retransmitts the telegram (with a modified sensor counter value) to the
next unit in the network via opposite CAN-output, i.e. if kSensNumDirectCountCommand is
received via CAN1 – it will be retransmitted via CAN2, and vice versa.
In the end of the procedure both
kSensNumDirectCountCommand telegrams, transmitted by
the master via CAN1 and CAN2, are received by itself via opposite CAN-ports, e.g.
kSensNumDirectCountCommand
, transmitted from masters CAN1, is received via masters
CAN2, and vice versa.
CAN channel Tag data item of the received telegram is used for additional verification of op-
posite source CAN-port and destination CAN-ports.
Received running sensor counter (direct counter) value represents actual number of sensors in
the network and is displayed with parameter 2581 UnitNumberCounter .
If direct counter value (parameter 2581 UnitNumberCounter ) is equal to preset sensor number
stored in evaluator (parameter 200
OMDSensorUnitsNumber
) - verification succeeds, that is
displayed with parameter 2580 UnitNumberApproved = 1.
In case of unit number verification procedure success, ID distribution sequence can be initiat-
ed by evaluator. Otherwise, verification failure scenario should be considered.
7.1.2 Network connection break scenario
In case of connection problem between any two units in the CAN-chain, kSensNum-
DirectCountCommand , sent by the master, will not reach its opposite CAN-input. The prob-
lem is detected by the master when
kSensNumDirectCountCommand
is not received within
certain timeout, and is displayed with parameter 2582 CanNetFailure = 1. Therefore sensor
number verification is not possible with kSensNumDirectCountCommand in such case. The
alternative way to verify unit number is using
kSensNumReversCountCommand
.