Power Monitoring via SNMP (or Modbus TCP)

WattNode configuration considerations

There is one configuration parameter that must be set in the WattNode in order to obtain correct current and power readings. The CT range you have connected to the WattNode must be entered into the variable named nciCtAmps_f.

The register number that corresponds to this will change depending on which additional variables further up the list you have selected for mapping. In our example above, it was auto-allocated to register 1009.

We need to set this value one time. It is stored in non-volatile memory in the WattNode. Since this memory has a finite write cycle life, you do not want to automatically re-write it every 5 seconds. At the very least, set the update time to 1 hour. The better choice is to manually write this value once, then unmap it (uncheck to map box for that register, and re-save your configuration file).

If you choose to leave nciCtAmps_f mapped, you must assure the correct value gets written back to that variable when the system restarts. You can do this by setting up a Constant as shown below. In this example, our CT range is only 5 amps (our lab test model). You are more likely to enter 100 or 250, etc., in this box.

To manually write nciCtAmps_f once, check the "map" box for nciCtAmps_f, then go to the System Data page, enter a value (we use our example of 5 amps again), check the update box, and click the Update button. Wait a minute for this data to actually get sent to the WattNode. You can confirm the change by observing a change in power readings.

Now go back to the LON Variables page and uncheck the map box. This variable will not re-appear when you save and reload your configuration file. To recover it, repeat the Get XIF from Device process for an opportunity to temporarily remap. If you do not save your temporary mapping, you can recover the original mapping by going to the Config File page and clicking the Load button.