Question

The goal of this FAQ is to explain how to monitor and transition a CanOpen slave device from STOP to OPERATIONAL mode using the application logic.

Answer

1. Issue

The goal of this FAQ is to monitor the status of a CANopen slave device and, if it is in STOP mode, change its state to OPERATIONAL mode using the application logic.

2. Product Line

Hardware: BMECXM0100 (CANopen Master)
Relevant objects: Slave DDT object HEALTH
NMT commands and Write_SDO EF functionality are used for state control.

3. Environment

• Operating System: Windows 11
• Software: EcoStruxure Control Expert (or equivalent), supporting CANopen communication
• Communication: CANopen protocol with NMT state machine and SDO commands

4. Resolution

• Monitoring Slave Status:

The status of each slave is available in its DDT under the object named "HEALTH".

• Health Parameter:

The table below describes the meaning of each value for the HEALTH parameter:

Example: If the Health byte equals 6, the slave is in Operational mode.

• Changing the Slave State:

If a CANopen slave connected to a BMECXM0100 master is in STOP mode, you can send an NMT=H05 command to force it into Operational mode.

Below is a diagram of the NMT State Machine and the list of available NMT commands:

This NMT command can be send by the application logic, using a WRITE_SDO communication EF.

• How to Use WRITE_SDO:

Here's a detailed explanation:

• • • SUBINDEX: Address of the target slave (e.g., @3 in this example)
    • NODE:  Must contain 127 (represents the sending device, the CXM)
    • INDEX: Must contain the NMT command encoding 16#1F82.
    • DATA_IN: Must contain the NMT command value, e.g., H05 for Operational mode
    • In the application, the variable SDO_DATA_TO_WRITE is a 49-byte unlocated array.

      

    • Here is an excerpt from an animation table that sends command 05 to move the slave into in Operational mode:

      
  • The EF is triggered when the input start_single_CMD = 1.
  • Note: Entering 16#04 will put the slave into STOP mode.

• Attached are:
• • The section for using the Write_SDO EF to control a slave.
  • The section for enabling the Write_SDO query.

5. FAQ Applicable Conditions (Optional)

This procedure applies to BMECXM0100 masters controlling CANopen slaves. It remains valid until firmware updates introduce alternative methods for state control.