BACnet plus POE communication unstable

We have three data halls with ten HUM-W-POE sensors in each, configured for both PoE and BACnet. We eventually lost communication with all of them. We restarted the sensors and regained communication briefly. One of our engineers discovered that the communication was switching between BACnet and Modbus, at which point we lost communication again. We couldn’t find a way to disable the Modbus protocol. Do you have any suggestions?

The Modbus packets could be some housekeeping or scanning that T3000 is doing in the background, on IP networks that should not cause problems. On RS485 networks that would definitely be an issue.

To get started, my usual suggestion is to start off by making sure you have the latest firmware by navigating to T3000 → help → check for updates → Update firmware.

If you are polling the devices heavily that could cause problems, slow down the polling activity to see if that helps. Also if you are polling a lot of Bacnet data you can combine them into a block read, this command is available over both Bacnet objects and Modbus registers.

You could temporarily power teh devices over regualr 12-24V AC/DC to see if that helps. Our POE has been out quite a while but its possible that there’s something going on in your particular environment.

Sounds like you are familiar with packet logging already, send on a log and perhaps we can spot something from that.

Hi Maurice,

I will connect to one of the sensors and update the firmware as soon as we can access the site. Currently, it’s a turnover space, so we need to wait.

I have also updated the T3000 software.

I will let you know how it works and will provide a log for review.

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I updated T3000 and downloaded firmware and updated the sensor too, It couldn’t finish to update and at this moment the sensor is blinking white screen. What do you suggest?


Please search the forum for ‘unbricking’, basically you cycle power and hit the flash button in the first few seconds after power up.

MD