Lika CANopen SFA-10000-CB, Руководство пользователя

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Glossary of CANopen terms
CANopen, like many other networking systems, has a set of unique terminology. Table below contains a
few of the technical terms used in this guide to describe the CANopen interface. They are listed in
alphabetical order. The Glossary is owned and copyrighted by the CAN in Automation international users'
and manufacturers' group.
Application layer The application layer is the communication entity of the OSI
(Open System Interface) reference model. It provides
communication services to the application program.
Application objects Application objects are signals and parameters of the
application program visible at the application layer API
(application programming interface).
Application profile Application profiles define all communication objects and
application objects in all devices that the network consists of.
Asynchronous PDO An asynchronous PDO is transmitted whenever a defined
internal event occurs. This event may also be the elapsing of
the PDO's event timer. If an asynchronous PDO is received the
protocol software immediately updates the mapped objects in
the Object Dictionary.
Boot-up message CANopen communication service transmitted whenever a
node enters the
Pre-operational
state after initialization.
Bus Topology of a communication network, where all nodes are
reached by passive links, which allows transmission in both
directions.
Bus analyser Tool, which monitors the bus and displays the transmitted bits.
There are bus analysers available on the physical layer, the
data link layer, and different application layers (e.g. CANopen
or DeviceNet).
Bus arbitration If at the very same moment several nodes try to access the
bus, an arbitration process is necessary. At the end of this
process, only one node has bus access. The bus arbitration
process used in CAN protocol is CMSA/CD (Carrier Sense
Multiple Access/Collision Detection) with AMP (Arbitration on
Message Priority). This allows bus arbitration without
destruction of messages.
Bus length The network cable length between the both termination
resistors. The bus length of CANopen networks is limited by
the used transmission rate. At 1 Mbps the maximum length is
25 m. When using lower transmission rates, longer bus lines
may be used: at 50 kbps a length of 1 km is possible.
Bus off state The CAN controllers switch to bus off state when the TEC
(transmit error counter) has reached 255. During bus off state,
the CAN controller transmits recessive bits. When a CANopen