Filter Received Can Messages - PROEMION CANlink wireless 3000 Series Device Manual

5.2.4

Filter received CAN messages

The device provides the option of setting parameters for message filters. This enables you to
reduce the transmission load on the radio Interface or ensures that the CAN bus only transmits
certain CAN messages to the radio interface.
In the CAN Receive tab in CANlink wireless Configurator, you can set filter masks and enable or
disable individual bits for the comparison function of online CAN objects. You can choose from
eight online CAN objects to specify which CAN identifiers are filtered.
A CAN message that does not conform with the reception filter of an online CAN object is
passed on to the next active online CAN object and checked again. If the number of CAN
identifiers to be filtered is smaller than eight, you can allocate a CAN identifier to each online
CAN object. Use the filter mask 0x7FF for11-bit or 0x1FFFFFFF for 29-bit CAN identifiers in
order to filter individual CAN identifiers.
Some examples are described in more depth below.
NOTICE
To check whether a CAN identifier fits a filter mask, perform the following logical operations
bit by bit:
CAN identifier received XOR configured CAN identifier = X
X AND filter mask= 0
The CAN message is rejected if the value is not 0.
Example 1:
0x123 XOR 0x621 = 0x702
0x702 AND 0x0F8 = 0 (CAN message accepted)
Example 2:
0x123 XOR 0x631 = 0x721
0x721 AND 0x0F8 = 0x010 (CAN message rejected)
TIP
Use D
OWNSAMPLING
Interface. The configured value (e.g. 1 x 10 ms for 10 ms) delays the reception or
transmission of CAN messages accordingly. A value of 0 x 10 ms disables the delay.
Only use D
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Device Manual
to reduce the number of messages to be transmitted by the radio
with filters for individual CAN identifiers!
OWNSAMPLING
CANlink wireless
Operation
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