1 Features and System Configuration
1-10
CJ-series User Defined CAN Unit Operation Manual for NJ-series CPU Unit (W517)
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.
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,
for
details).
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).
OSI Layer 7: Higher Layer Protocol
1-2-2
Physical CAN Connection
Microcontroller
+6 V
CAN Controller
TX0
TX1
RX0
RX1
CAN Transceiver
TxD
RxD
Ref
Vcc
Gnd
CAN_H
CAN_L
CAN_H
CAN_L
CAN Bus Lines
R
T
R
T
Bus Termination
Bus Termination
100 nF
Содержание CJ1W-CORT21
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Страница 134: ...6 Troubleshooting and Maintenance 6 18 CJ series User Defined CAN Unit Operation Manual for NJ series CPU Unit W517...
Страница 140: ...Appendices A 6 CJ series User Defined CAN Unit Operation Manual for NJ series CPU Unit W517...
Страница 141: ...Index 1 CJ series User Defined CAN Unit Operation Manual for NJ series CPU Unit W517 I Index...
Страница 144: ...Index 4 CJ series User Defined CAN Unit Operation Manual for NJ series CPU Unit W517 Index...