Physical Can Connection - Omron CJ1W-CORT21 Operation Manual

1 Features and System Configuration
 Identifier Length
Standard format
The identifier's length is 11 bits and corresponds to the Base Id in the Extended format. The indenti-
fier is interpreted as an integer value in the hexadecimal range 0x0000 - 0x07FF.
Extended format
In contrast to the Standard format, the identifier in this format consists of 29 bits. The format com-
prises two sections; Base Id and Extended Id. The Base Id consists of 11 bits and is the identifier for
the Standard format. The Extended Id consists of 18 bits and with the Base Id this is 29 bits. The
indentifier is interpreted as an integer value in the hexadecimal range 0x00000000 - 0x1FFFFFFF.
OSI Layer 7: Higher Layer Protocol
Examples of the higher layer protocol in OSI layer 7 are DeviceNet and J1939 (a set of standards con-
cerning the design and use of devices that transmit and receive electronic signals and control informa-
tion). For the User Defined CAN Unit, the higher layer protocol is implemented in the user program of
the controller. Received CAN messages are stored in controller memory areas. The CAN messages to
transmit are formatted in the user program and (temporarily) stored in CPU memory areas. The location
and size of these memory area's are defined with message commands. Separate message commands
can be used for direct transmission of CAN messages (see Section 4, Message Communications for
details).
1-2-2

Physical CAN Connection

 ISO 11898
The data rates (up to 1 Mbps) necessitate a sufficiently steep pulse slope, which can be imple-
mented only by using power elements. A number of physical connections are basically possible.
However, the users and manufacturers group CAN in Automation recommends the use of driver cir-
cuits in accordance with ISO 11898. Integrated driver chips in accordance with ISO 11898 are avail-
able from several companies. The international users and manufacturers group (CiA) also specifies
several mechanical connections (cable and connectors).
1-10
Microcontroller
CAN Controller
TX0 TX1
TxD
CAN Transceiver
CAN_L CAN_H
CAN_H
R
T
Bus Termination
CAN_L
CJ-series User Defined CAN Unit Operation Manual for NJ-series CPU Unit (W517)
RX0 RX1
+6 V
RxD Ref
Vcc
100 nF
Gnd
CAN Bus Lines
R
T
Bus Termination