Contemporary Control Systems CANISA - Manual (Page 6)

PeliCAN Jumper Settings
(
�
= jumper installed X = don’t care)
Table 2 — 32-byte Addressing Table 3 — 128-byte Addressing
RA S4 S3 S2 S1 S0 I/O RA S4 S3 S2 S1 S0 I/O
Address Address
� � � � � 000 � � � � X 000
� � � � 080 � � �
X
X 080
� � � � 100 � � �
X
X 100
� � � 180 � �
X
X 180
� � � � 200 � � �
X
X 200
� � � 280 � �
X
X 280
� � � 300 � �
X
X 300
� � 380 �
X 380
CAN Operation
CAN is currently described by ISO 11898. In terms of the Open Systems
Interconnection model (OSI), CAN partially defines the services for layer 1
(physical) and layer 2 (data link). Higher-layer protocols such as DeviceNet
and Smart Distributed System define additional services of the seven layer
OSI model. Both of these protocols use CAN circuitry and, therefore,
comply with the data link layer defined by CAN.
Medium access control (MAC) is accomplished through non-destructive bit-
wise arbitration. If a station attempting transmission fails to confirm that its
data is being accurately propagated, it assumes a higher priority message is
present on the network. Consequently, it halts transmission and reverts to
receiving mode. The highest priority message gets through and lower
priority messages are resent later. In this way network collisions do not
destroy data and eventually all stations gain access to the network.
TD990520-0I
E
6
X
X