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SDO Object Dictionary & NMT Management

CAN & CANopen Studio includes a full-featured Service Data Object (SDO) communication console for querying and modifying parameters in target device Object Dictionaries.

Service Data Objects (SDO)

CANopen uses SDO for client/server peer-to-peer communication between the master (CANopen Studio) and target nodes.

  • Client-to-Server (SDO Rx): COB-ID 0x600 + NodeID
  • Server-to-Client (SDO Tx): COB-ID 0x580 + NodeID

Reading Object Dictionary Entries (SDO Upload)

  1. Navigate to the SDO Object Dictionary tab.
  2. Select target Node ID (e.g. 1).
  3. Enter the 16-bit Index in hex (e.g. 0x1000 for Device Type).
  4. Enter the 8-bit Sub-index in hex (e.g. 0x00).
  5. Click Read (SDO Upload).
  6. The application displays:
  7. Raw bytes returned by the device.
  8. Decoded integer / string interpretation.
  9. Status: Success or SDO Abort code.

Common CANopen Standard Dictionary Indices

Index Sub-index Object Description Typical Format
0x1000 0x00 Device Type UNSIGNED32 (CiA profile number)
0x1001 0x00 Error Register UNSIGNED8 bitmask
0x1008 0x00 Manufacturer Device Name VISIBLE_STRING
0x1009 0x00 Manufacturer Hardware Version VISIBLE_STRING
0x100A 0x00 Manufacturer Software Version VISIBLE_STRING
0x1017 0x00 Producer Heartbeat Time UNSIGNED16 (milliseconds)
0x1018 0x01 Identity Object: Vendor ID UNSIGNED32
0x1018 0x02 Identity Object: Product Code UNSIGNED32
0x6040 0x00 CiA 402: Controlword UNSIGNED16
0x6041 0x00 CiA 402: Statusword UNSIGNED16
0x6060 0x00 CiA 402: Modes of Operation INTEGER8
0x606C 0x00 CiA 402: Velocity Actual Value INTEGER32 (RPM or units/s)
0x607A 0x00 CiA 402: Target Position INTEGER32

Writing Object Dictionary Entries (SDO Download)

  1. Specify Node ID, Index, Sub-index.
  2. Enter the new value (decimal or hex).
  3. Select the data length (1, 2, or 4 bytes).
  4. Click Write (SDO Download).
  5. The device validates the value and returns a confirmation acknowledgment.

Network Management (NMT) & Heartbeat Monitoring

CANopen uses Network Management (COB-ID 0x000) for commanding nodes between operational states, and Heartbeat messages (0x700 + NodeID) for presence and liveness verification.

Supported NMT Master Commands (CiA 301)

  • Start Remote Node (0x01): Transitions the node into Operational state. PDO communication is active.
  • Stop Remote Node (0x02): Transitions the node into Stopped state.
  • Enter Pre-Operational (0x80): Enables SDO configuration while pausing PDO transmission.
  • Reset Node (0x81): Re-initializes device application and communication parameters.
  • Reset Communication (0x82): Re-initializes device communication stack only.

High-Performance Native NMT Engine

When canopen_core is compiled, NMT master command synthesis, state machine tracking, and microsecond-level heartbeat timeout detection are handled in zero-allocation native Rust (canopen_core.NmtMaster).

Electronic Data Sheets (EDS) & Object Dictionary Engine (CiA 306)

The compiled native core includes a CiA 306 Electronic Data Sheet parser (canopen_core.EdsFile):

  • Device & File Metadata: Reads [FileInfo] and [DeviceInfo] (Vendor Name, Vendor ID, Product Code, Revision Number).
  • Object Dictionary Instantiation: Parses index entries ([1000]) and subindex entries ([1018sub1]) with data types (UNSIGNED32, INTEGER16, BOOLEAN, etc.), access permissions (ro, rw, const), and default values.
  • Automated PDO Mapping Synthesis: Given a TPDO/RPDO mapping index (e.g. 0x1A00 for TPDO1 or 0x1600 for RPDO1), automatically builds a bit-accurate PdoMapping structure with resolved signal names, bit offsets, and engineering types:
from canopen_studio import canopen_core

eds = canopen_core.EdsFile.load_file("motor_controller.eds")
tpdo1 = eds.create_pdo_mapping(cob_id=0x181, mapping_index=0x1A00)
signals = tpdo1.decode_frame(frame)