Altivar Process ATV900 - Communication Object Identifier

Basics
NHA80945 04/2017 19
Communication Object Identifier
Description
The COB ID (communication object identifier) has 2 tasks as far as controlling communication object is
concerned:
 Bus arbitration: Specification of transmission priorities
 Identification of communication objects
An 11-bit COB identifier as per the CAN 3.0 A specification is defined for CAN communication; it comprises
two parts:
 Function code, 4 bits
 Node address (node ID), 7 bits
Function Code
The function code classifies the communication objects. Since the bits of the function code if the COB ID
is more significant, the function code also controls the transmission priorities: Objects with a lower function
code are transmitted with higher priority. For example, an object with function code A is transmitted prior
to an object with function code 3 in the case of simultaneous bus access.
Node Address
Each network device is configured before it can be operated on the network. The device is assigned a
unique 7-bit node address (node ID) between 1 (01 hex) and 127 (7F hex). The device address 0 is
reserved for broadcast transmissions which are used to send messages to all reachable devices
simultaneously.
COB IDs of the Communication Objects
The following table provides the COB IDs of the communication objects with the factory settings.
Communication object Function code Node address, node ID [1...127] COB ID decimal (hexadecimal)
Service Network
Management (NMT)
0 0 0 0 0 0 0 0 0 0 0 0 (0 hex)
Synchronization service
(SYNC)
0 0 0 1 0 0 0 0 0 0 0 128 (80 hex)
Emergency service (EMCY) 0 0 0 1 x x x x x x x 128 (80 hex) + node ID
Transmit PDO1 (TPDO1) 0 0 1 1 x x x x x x x 384 (180 hex) + node ID
Receive PDO1 (RPDO1) 0 1 0 0 x x x x x x x 512 (200 hex) + node ID
Transmit PDO2 (TPDO2) 0 1 0 1 x x x x x x x 640 (280 hex) + node ID
Receive PDO2 (RPDO2) 0 1 1 0 x x x x x x x 768 (300 hex) + node ID
Transmit PDO3 (TPDO3) 0 1 1 1 x x x x x x x 896 (380 hex) + node ID
Receive PDO3 (RPDO3) 1 0 0 0 x x x x x x x 1024 (400 hex) + node ID
Transmit SDO (TSDO) 1 0 1 1 x x x x x x x 1408 (580 hex) + node ID
Receive SDO (RSDO) 1 1 0 0 x x x x x x x 1536 (600 hex) + node ID
NMT error control (Node
Guarding, Heartbeat)
1 1 1 0 x x x x x x x 1792 (700 hex) + node ID