HBM SOMATXR, Руководство по эксплуатации, Страница: 28 / 152

Functional description
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A4461-2.0 HBM: public
CANBus
6.2.3 Possible error causes in CAN mode
6.2.3.1 CANbus warning, CANbus error,
CANbus OFF
An internal counter in the module’s CAN controller counts
the bus errors in accordance with the CAN standard.
When the first threshold is exceeded, a “Warning” is set,
and after that, an “Error”. If the cause of the error is
promptly eliminated, Warning and Error are automatically
deleted again.
If the error still remains, “BUS OFF” will ultimately be set.
The bus will become inactive/switch off. Once the cause
of the error is eliminated, the state in the module is
deleted by an external BUS reset, parameterization or
re-starting the module. A BUS reset can be triggered by
all MX471B and MX840B variants, but not by MX840 and
MX840A.
Errors on the CAN bus are then counted in the CAN
controller, for instance, if no correct response is received
from the other side during transmission (because no
recipient responds by acknowledging), or if the bus is
malfunctioning due to a short circuit, incorrect bus termi­
nation, mixed operation at different bit rates, or other
(usually) electrical properties.
6.2.3.2 CAN “Receiver Overrun”
If the CAN controller in the module cannot read out the
data quickly enough, the data present on the CAN bus
are lost, and the “Overrun” flag is set. At this moment in
time, no-one knows whether the lost data are relevant,
that is, whether the CAN identifier for this message is
parameterized in the decoder.