Troubleshoot Device Connectivity Status
Estimated reading time:
2 minutes
At times, a device may display as Disconnected, as in the following example.
Why is the Device Disconnected?
Certain conditions cause a PLC to be disconnected in OT Link Platform.
Condition |
Reasons PLC Appears as Disconnected |
Steps to Connect the Device |
Free Tag: Explicit register name required
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- Certain device drivers, such as Allen-Bradley CompactLogix, will not have a list of register names in the DeviceHub Add Tag form.
- When a list of registers is not provided, the case-sensitive register name must be entered exactly as it is defined in the PLC.
- In these cases, the device will not display a Connected status until a tag with a correct register name is created.
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- See DeviceHub Add a Tag and DeviceHub Manage Tags to add a tag with a case-sensitive register name.
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HID Device in Wait State |
- Some HID (Human Interface Devices), such as barcode scanners, are always disconnected and only show a connected status when they send data to OT Link Platform.
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- This is a temporary state and no intervention is required. The device will connect when there is data to receive.
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Incorrect PLC Configuration |
- If configuration changes have been made to a PLC, the best way to ensure accurate OT Link Platform status is to delete and recreate the DeviceHub Device.
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- Delete the DeviceHub Device. See DeviceHub Add, Monitor, or Delete Device.
- Create a new DeviceHub Device with the correct PLC configuration.
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Incorrect Tag Information |
- To prevent the PLC from going into fail safe mode or from crashing the process when a tag has incorrect information, OT Link Platform disconnects communication with the PLC.
- For example, a tag may contain an incorrect address.
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- Monitor all the tags in Flows to identify the bad tag.
- Find the tag with a success flag set to false.
- Delete the tag from DeviceHub. See DeviceHub Manage Tags.
- If there is no data on the flows, restart the PLC. If a node in a flow indicates "waiting for messages" and nothing is displayed in the debug console, this means that OT Link Platform has stopped communicating with the PLC, so there is no data.
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