NI-Industrial Communications for EtherCAT and the NI Scan Engine
- Updated2023-02-21
- 2 minute(s) read
NI-Industrial Communications for EtherCAT and the NI Scan Engine
NI-Industrial Communications for EtherCAT leverages the NI Scan Engine to provide the I/O variable.
The NI Scan Engine allows efficient access to coherent sets of data channels, such as I/O channels, using a scan that stores data in a global memory map. The NI Scan Engine also updates all values at a single rate, known as the scan period. Refer to the LabVIEW Help for the more information about the NI Scan Engine.
EtherCAT State and NI Scan Engine Mode
Overview
The NI Scan Engine controls the NI-Industrial Communications for EtherCAT master. The following table shows the modes of the NI Scan Engine.
| Mode | Description |
|---|---|
| Configuration | The required mode for configuring NI Scan Engine settings and hardware on the EtherCAT network. I/O variables are not updated with real data. |
| Active | In this mode, the NI Scan Engine actively updates I/O variables with real data from the EtherCAT network. |
EtherCAT slave devices have the following states.
| State | Description |
|---|---|
| Operational | The EtherCAT slave device supports full process communication and mailbox functionality in this state. |
| Safe-Operational | The EtherCAT slave device supports mailbox functionality, but only input process communication in this state. The output process communication of the slave device does not function in this state. |
| Pre-Operational | The state in which the EtherCAT slave device supports mailbox functionality such as SDO. The slave device process communication, PDO, does not function. |
| Init | In this state, the EtherCAT slave device does not communicate on the application layer. |
| Bootstrap | The state in which you can download the slave device firmware. |
Automatic Mode Transition
The NI-Industrial Communications for EtherCAT master changes the states of the slave devices. The following rules outline how the master automatically controls the NI Scan Engine modes and the states of the EtherCAT devices.
- When the NI Scan Engine is placed in Active mode, the master transitions all slave devices to their Operational states. The operation may fail if the devices are not properly configured.
- When the NI Scan Engine goes to Configuration mode, the master transitions all slave devices to their Pre-Operational states.
- Deploying any changes to the project or undeploying the EtherCAT master automatically transitions the NI Scan Engine to Configuration mode.
- With the default settings after new settings are deployed, the NI Scan Engine automatically transitions to Active mode. You can control this behavior by choosing to report automatic mode transitions as conflicts inside the real-time controller's Scan Engine settings.
- If nothing new is detected in the LabVIEW project, deployments do not trigger an NI Scan Engine change.
- Running a VI automatically triggers a deployment. Whether a mode change occurs depends on the current NI Scan Engine mode and whether anything actually was deployed to the target.