Sys Tec Electronic GW-003 - Filtering; Concept of Message Filtering; Input Filter; Output Filter

CAN – Ethernet Gateway
34 © SYS TEC electronic GmbH 2007 L-1032e_9
4.3 Filtering
4.3.1 Concept of Message Filtering
The filtering is based on the screening of CAN identifiers. The CAN-
Ethernet Gateway processes the data from the Ethernet or CAN in a
data pool. The filter rules determine which messages will be passed on
from this data pool. Thus data traffic can be reduced if, for example,
only messages from a certain group of CAN identifiers (CAN IDs) are
passed on. Furthermore, individual CAN identifiers can be selected for
highly specific filtering schemes.
The filter rules can be determined by calling an interface's filter files.
If no filter rules are present then all messages are passed on.
4.3.2 Input Filter
The input filter determines which messages will be accepted by the
interface input (
fin). For example, with a CAN interface only the
messages whose CAN IDs are established in the
fin function will
reach the CAN-Ethernet Gateway.
4.3.3 Output Filter
The output filter determines which messages from the Gateway’s data
pool will be passed on (
fout).