S2Tech PCS III, Предварительное руководство

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DIGITAL TRANSDUCER
Configuration and CAN Interface
PRELIMINARY CANopen
PCS III Technical Description CANopen 1r1 UK 310715.docx
09/02/2021 S2Tech srl
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Reply Message sent from Slave to Master has the following format:
COB-ID Byte0 Byte1 Byte2 Byte3 Byte4 Byte5 Byte6 Byte7
TxSDO + Slave
Node Id Answer Index
Low Index
High Subindex Data0 Data1 Data2 Data3
COB-ID TxSDO + Node Id
The Slave sends its TxSDO to Master, i.e. a Slave SDO with Node Id 7 use a CAN
message with COB-ID 7 = 0x0587.
Answer Byte0 of the CAN message contains the SDO protocol reply code (read, write….)
Among others, valid command codes are :
0x60 Write OK
0x4F Read BYTE (8 bit)
0x4B Read WORD (16 bit)
0x43 Read LONG (32 bit)
Index Byte1 and Byte2 of the CAN message contain the Index, expressed as a 16 bit number in
little endian format , Byte1 contains LOW byte, while Byte2 contains HIGH byte.
Subindex Byte3 of the CAN message contains the Subindex, expressed as an 8 bit number
Data In case of a read command, Byte4 to Byte7 of the CAN message contain the value read
from the Object addressed by Index and Subindex, in little endian format , Byte4 contains
LOW byte, Byte7 contains HIGH byte.
19. Operating the CANopen device
A CANopen device, following the DS301 specifications from a connection point of view, can be in two different connection states, called
PreOperational and Operational .
After Reset , at power on or after a restart command, the device is by default in PreOperational state.
It transmits a Node Guarding message and, optionally, some Emergency messages (EMCY), indicating its “wakeup” conditions. (Message
COB-IDs are assigned according Table 1).
Unless the Network Master needs to keep track of unexpected reset or error conditions, these messages can be totally ignored, otherwise
their meaning can be found into the CANopen DS301 specification (Node Guarding) and into the specific device User’s Manual
(Emergency Message).
A device can exchange Service Data (SDO) in any state, while Process Data (PDO) can be exchanged only when the network is in