Direct Emon Driver Support


Since install, our Emon dedicated Jace’s on N4.2 have been frequently locking up and requiring manual reboots. I am looking to bring in any developer with first hand experience in the Emon N4 driver development to provide direct support. Can someone please put me in contact with anyone that may be of help? Also, is there any plan to upgrade the Emon N4 Driver to provide support beyond v4.0.22.16 in the near future?


The current version should work with any release prior to 4.3.

  1. Can you describe the process by which you have experienced the lockup issue?
  2. What criteria was used to determine the driver was the cause of the lockup and requiring a station reboot?
  3. Can you give some details about other troubleshooting techniques that were used before restarting the station?


Thanks Jonathan.

It may be best to do a screen-share to show you our setup. Also, are you able to schedule some paid time to consult with you in person or remotely?

We have 7 different risers of Emon meters in our building. Each riser has about 50 recorders (meters and IDRs). Two (2) separate Jaces are running AX Version 3.8.213 with the AX Emon Driver, with two risers per jace. Three (3) Separate 8000 Jaces are running with the N4 Emon Driver, with one meter riser per jace. There is nothing on the Jaces other than the Emon Driver and the meters. The history and points on the Jaces is polled through and nHaystack service. We had started the process of upgrading to N4 and splitting each riser onto its own dedicated Jace (rather than two risers per jace). The goal was to make the site current and to eliminate the issues that we are experiencing on the AX Emon Driver (detailed below), however we are still having issues on N4, even with the reduced one riser per jace.

The AX Jaces are repeatably experiencing serial port errors on one or both of the risers. We have tried to disable and then enable the error-ed riser, but that doesn’t clear the serial port errors. The only way to clear the error is to disable both risers on the jace, then reboot the jace at the platform, and then enable both risers. Every time this works to clear the issue.

The N4 Jaces are experiencing different issues. The entire Jace locks up and you cannot even login, and receives a Target Not Found error. The only way to clear this issue is to login to the platform and reboot the Jace. I have saved many application director outputs prior to rebooting if you think reviewing the could help diagnose.

We are trending 6 electric points on each electricity meter and both usage and demand points for the Emon IDRs. We have also created health trends to track when the meters and risers go into error. We have also disabled all points without trends on the electricity meters in an attempt to reduce traffic.

I hope the above has answered all your questions.


I believe based on that description you are experiencing a memory leak in N4 ( that was patched in 4.3 and above. This is a memory leak found in the web service of Niagara. Using the nHaystack to poll will cause multiple web requests to the JACE’s which will slowly cause this memory leak to build until there is no memory left. Memory leaks tend to cause difficult trouble shooting scenarios as things no longer function as expected when memory is no longer available for processes to function so I would recommend first upgrading to 4.3 or temporarily disable haystack polling to verify more stable behavior before we can rule that out as the cause of the failures.


As for the AX serial port lockup, could you provide any stack trace and/or error messaging that relates to this issue?


You previously mentioned that the current Emon Driver release would work with any N4 version prior to 4.3. Just to be clear, are you recommending that we upgrade to 4.3 or 4.4 to see if the memory leak issue is resolved? We also can map the points from the stand alone metering Jaces to a supervisor BAS account and poll the data that way.

I’ll pull together some error messaging the next time the serial ports lock up on an AX jace and send.


You are correct in that the emon driver likely will experience some issues with 4.3 due to some security changes that haven’t been accounted for so upgrading would be difficult. If you can do the polling elsewhere off of the 4.2 JACE’s, this should at least slow down the memory leak considerably until an update can be provided to allow for a full upgrade of the Niagara version.


Thanks Jonathan. We will move forward with polling the points from another location (Supervisor).

Do you have any schedule for when I can expect the update to the Emon N4 Driver? Also, is there anything I can do to help speed it along?