Troubleshooting LNS Communication Issues (KB149)

Reasons for Communication issues:

1. Many device communication issues are due to trying to communicate to a device using the wrong neuron Id or programming Id.
   • Commissioning may fail or not start if the device has a different Program ID then the LNS device template.
2. There is a short or break in the LonTalk cable.
3. Too much communication slows down device responses such that the LNS timers expire.
4. The device has failed.

Use one or more tools to see if there is any communication to the device:

1.  Using NodeUtil or LonWorks Interfaces App (Windows Control Panel) see if you can see a service pin message from this device.
   • Does the Neuron ID match and program ID match the device.
   • If NodeUtil is using your Network network interface and you see the service pin message then this indicates that you have some level of communication but doesn't mean that there is no channel or device issues.
2. Use NodeUtil (3.51+) and the devices neuron ID or service pin and see if you can communicate to the device.
   • A device can be added to NodeUtil by pressing the service pin or by "a" adding the device neuron ID.
   • If you can communicate to the device type "g" enter the device number or press enter key to go to the device menu. Type "s" to get the device status. Check the last error
   • This problem can occur if the device is watch dogging. That is, the device is constantly resetting due to a watch dog timer. This usually occurs do to an inifintite loop, or code that takes too much time in the devices neuron C code.
   • Go near the edge device with a U10 and see if nodeutil can communicate to the device.
     
     
3. Use LonScanner to see if you can see a responses from the edge device.
   • Check channel bandwidth to see if there is too much channel data (sustained bandwidth should be below 40%).
   • Use LonScanner at both the network interface and at the edge device (if you are using an i.LON or SmartServer for your Network interface then you can use a U10 at the edge device and open a LonScanner for both network interfaces to see traffic at both ends).
   • See if you get any response from the edge device, you may need to do a managed test either in the LNS tool or using NodeUtil (device menu "s" command).
   • Even if you see responses if the responses take too long you could get an NS, #26 error (you can change the LNS timers to make them longer).