A wireless sensor is expected to collect data at a scheduled time each day. A sensor could go offline for a number of reasons which would prevent data from being captured. Here are the common causes and solutions for Sensor is Offline.
There are two primary indicators that a sensor is offline.
1. The Online Dashboard displays "Offline" or "Unknown" in the Network Connectivity column.
2. The last collection time, the latest results, or the last set of scalar values have lapsed for a period of time.
Possible Reasons and Solutions
1. Sensor Powered Off. The button could have been pushed on the sensor, effectively the sensor has been powered off. The sensor could have also been powered off using the control in PredictivePortal. The status of the sensor is expected to indicate when the sensor has been powered off using the user interface in the portal. If the sensor button was used to turn off the sensor, the portal indication may be unknown. Try pushing the button per the User Manual to confirm the double green flashing LED, indicating the sensor has a solid connection to the gateway. Turn on the sensor as required.
2. Lost Connection. The sensor lost its connection to the gateway. A sensor could have fallen off the machine and thus can't get a signal or some interference has occurred, like a truck is parked in the way, blocking the sensor from making a connection to the gateway. Ensure the path is clear and the sensor is properly installed. Use the power button on the sensor, per the User Manual, to confirm a double green flashing LED, indicating the sensor has a solid connection to the gateway. If obstacles occur frequently, adding additional relay sensors to the mesh network could help maintain a solid network connection.
3. Low Link Quality. Link quality is like signal strength, how good is the connection between the gateway and sensor or between sensors. Link Quality is an indication currently visible by Technical Support to help troubleshoot problems but will soon be added to PredictivePortal. The best solution for low link quality is to add additional relay nodes to bridge the gaps in the mesh network.
4. Mesh Hop Offline. The sensors will attempt to find the best path to a gateway. If a gateway goes offline, the sensor will look to see if it can make a path to another gateway. If no other gateways are available, the sensor could appear offline. Additionally, if a sensor uses another sensor or a relay node to establish a connection to the gateway, ensure these devices are also online as necessary. Use the power button on the sensor, per the User Manual, to confirm a double green flashing LED, indicating the sensor has a solid connection to the gateway. Additional relay sensors could be added to the mesh network to help maintain a solid network connection.
5. Dead Battery. It is entirely possible that the battery of the sensor has died. The battery is expected to last no less than 3 years with daily diagnostic data collection and with a managed mesh network of sensors to gateways. If there are too many hops within the mesh network, the sensors closest to the gateway will have a higher degradation of battery life. If you find sensors closest to the gateway seem to have gone offline, a dead battery could be a culprit. The battery indicator should present the last known status of the battery. But if this is unknown, contact Technical Support to provide some investigation.