Troubleshooting CANopen Applications

NI-Industrial Communications for CANopen 1.0.2 Help

Edition Date: July 2012

Part Number: 373254C-01

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The following issues are some common issues you might encounter when you create or execute CANopen applications. Follow the guidelines to troubleshoot CANopen applications.

  • All CANopen operations return failures.
    • A possible reason for these failures is that the CANopen devices use inconsistent baud rates. All CANopen devices must use the same baud rate on a CANopen network. Ensure all operations use the same baud rate. For example, if the baud rate of a device is 1 Mbps, the baud rate of the CANopen interface must be 1 Mbps.
  • LabVIEW fails to change node-IDs or baud rates of some devices.
    • LabVIEW uses layer setting services (LSS) to change device node-IDs and baud rates. If a device does not support LSS, you cannot change the node-ID or baud rate by using LabVIEW dialog boxes or VIs. You can change the node-ID or baud rate by using switches on the device.
    • Some devices support LSS in the stopped state only. You can use the CANopen NMT Write VI to switch the device into the stopped state before changing the node-ID or baud rate.
  • After LabVIEW changes a node-ID or a baud rate, the change does not take effect.
    • Some devices need to reset to apply the new node-ID or baud rate. Use the CANopen NMT Write VI to reset the device. You need to use the original node-ID or baud rate to send the reboot command. For example, after you change the node-ID from 2 to 3, you need to reset the device with the original node-ID 2. The device switches into the new node-ID 3 after the reset.
  • The device does not change states when receiving a network management (NMT) message.
    • Some devices need several seconds for state transition. For example, if you send out a reset command, a device may need five seconds to reset all the parameters and enter the pre-operational state.
  • The device does not support service data objects (SDOs).
    • Devices support SDOs in the pre-operational and operational states only. You must switch a device into either of these states to use SDOs.
  • The device does not support process data objects (PDOs).
    • Devices support PDOs in the operational states only. You must switch a device into the operational state to use PDOs.
  • The Online Test Panel does not display certain devices.
    • The Online Test Panel scans devices in the pre-operational state only. Ensure the device is in the pre-operational state and re-scan devices in the Online Test Panel. If the device is not in the pre-operational state, send an Enter pre-operational command to switch the device into the pre-operational state. You can send the command by using the NMT status page of the Online Test Panel dialog box or the CANopen NMT Write VI.
  • The Online Test Panel takes a long time to scan devices.
    • The Online Test Panel uses the specified baud rate to scan devices. You can switch all devices to a faster baud rate to improve the performance of the Online Test Panel. For example, if the original baud rate is 10 kbps, you can change the baud rate to 1 Mbps to improve the performance.
  • The Change Device Baud Rate dialog box takes a long time to change a device baud rate.
    • If you place a checkmark in the Try all baud rates checkbox, LabVIEW detects the current baud rate of the device. You can disable the detection to improve the performance. You may disable the detection by removing the checkmark from the checkbox and specifying the current baud rate manually.
  • The CANopen CAN Frame Read VI and the CANopen CAN Frame Write VI cannot read or send CANopen frames.
    • When you transit a CANopen frame from an interface, you cannot read this CANopen frame by using the original interface. You must assign another interface to the CANopen CAN Frame Read VI to read the CANopen frame. Otherwise, the CANopen CAN Frame Read VI cannot read the message.
    • Devices may need some time to transmit and receive CANopen frames.
  • In Measurement & Automation Explorer (MAX), a PXI device does not display the slot number.
    • Re-identify the PXI device and the chassis to show the slot number. Right-click the PXI device in MAX and select Identify As»Device_model to re-identify the PXI device. Perform the same steps to re-identify the chassis.
  • The error status LED of the device is solid red.
    • The CANopen bus has devices that use different baud rates. Change device baud rates to the same baud rate by using the Online Test Panel dialog box. Re-open the CANopen interface with the new baud rate to clear the error.
    • The baud rate that you use to communicate with this device does not match the device baud rate. Ensure you use the correct baud rate and re-open the CANopen interface to clear the error.


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