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 LoopEdge.
|Condition||Reasons PLC Appears as Disconnected||Steps to Connect the Device|
Free Tag: Explicit register name required
- 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.
- See DeviceHub Add a Tag and DeviceHub Manage Tags to add a tag with a case-sensitive register name.
|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 LoopEdge.
- This is a temporary state and no intervention is required. The device will connect when there is data to receive.
|Incorrect PLC Configuration|
- If configuration changes have been made to a PLC, the best way to ensure accurate LoopEdge status is to delete and recreate the DeviceHub Device.
- Delete the DeviceHub Device. See DeviceHub Add, Monitor, or Delete Device.
- Create a new DeviceHub Device with the correct PLC configuration.
|Incorrect Tag Information|
- To prevent the PLC from going into fail safe mode or from crashing the process when a tag has incorrect information, LoopEdge disconnects communication with the PLC.
- For example, a tag may contain an incorrect address.
- 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 LoopEdge has stopped communicating with the PLC, so there is no data.