Why Won't My WSN Node Connect to the Network?

Updated Mar 22, 2018

Reported In

Hardware

  • Analog Input Node for WSN
  • Strain/Bridge Node for WSN
  • Serial Interface Node for WSN
  • Thermocouple Input Node for WSN
  • WSN-9791
  • WSN-9792
  • RT Controller with Integrated Gateway for WSN

Driver

  • NI-WSN

Issue Details

I have a wireless sensor network (WSN) node that is consistently indicating that it is trying to connect to a network and is not returning any data. Why won't the node connect to the network?

Solution

A node may fail to connect to the network for a variety of reasons. Use the following guide to help troubleshoot this problem:
  1. Make sure that the node has been added to the gateway.
In order for a node to connect to a network, the gateway must expect it to be a member. It is possible that the node has not been properly added to the gateway in MAX. Also check that your configuration settings have been applied.  For more information on how to add a node to the gateway, refer to Start»All Programs»National Instruments»Wireless SensorNetwork 1.0»Configuring WSN in MAX. 
  1. Verify that the node is in communication range of an available gateway or router. 
It is possible that the node is simply not able to communicate with the gateway or any routers. The node's outdoor range is up to 300 m for American models.   Europe/Asia models have an outdoor range up to 150 m. Make sure that the node is within this distance to its desired parent. Also keep in mind that even though the nodes have this listed specification, it is possible for sources of interference to significantly limit this range. If possible, first place the node close to its parent and allow it to connect, then move it to its desired location and see if it can maintain its connection. 
  1. Verify that your network configuration properly avoids the possibility for a stranded node. 
Gateways and routers can only facilitate the communication of 8 end nodes at a time. If your network contains more than 8 end nodes, it is possible for some of them to become stranded and fail to join. For more information on how to prevent stranded nodes, refer to pg. 15 the NI WSN-9791 Ethernet Gateway user manual or page 22 of the NI 9792 WSN Real-Time Gateway user manual.
  1. Make sure the node is not searching on the wrong channel.
If a node was previously connected to a network on a different communication channel it may still be attempting to join on that channel. To ensure that this is not an issue, hold the Communication Button on the node for at least 5 seconds to allow it to restart the connection process. For more information on this, refer to Changing the Gateway Communication Channel Does Not Automatically Change Node Channels.
  1. Check that the node is not simply asleep. 
After failing to join a network, an end node will sleep before trying to reconnect. This is done to help conserve power. The node will sleep an increased amount of time between failed attempts. The nodes use the Fibonacci sequence (1, 1, 2, 3, 5, 8, 13, 21, 34, 55) to determine wait times. The nodes can wait up to 55 minutes between connection attempts. As result the end node may simply be asleep and may not be actively trying to join the network. To force joining attempts from the node, either hold down the Communication Button on the node for at least 5 seconds or press the Reset button.
  1. Check that other nodes that have not been added to the gateway are not currently trying to connect.
Connection problems can occur if multiple nodes are attempting to connect to the network but are not being allowed by the gateway because they have not been added in MAX.  When this happens, there is a chance that nodes that are permitted to join will not be able to.  This problem should resolve itself eventually on its own.  However, the best way to prevent this behavior is to ensure that all of your nodes have either been added to the gateway in MAX or have been powered down.
  1. If after verifying the above the node still will not connect, it may have incompatible or corrupt firmware. 
It is possible that the node firmware is incompatible with the gateway or is corrupt. It is also possible for a user-created program running on the node to prevent the node from communicating regularly. This will cause the node to drop from the network and can prevent it from rejoining. To resolve this problem, reset the node to its factory firmware by pressing and holding the Reset button for at least 5 seconds. The node should then reconnect and allow the appropriate firmware to be reinstalled.

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