Dear

We are currently using Neptronics Gold thermostats. We are experiencing issues with Bacnet MSTP communication between Siemens and Neptronics thermostats.

Issue Details:

We have configured each thermostat separately, assigning unique MAC addresses and instance numbers. When connected individually, each thermostat communicates correctly. However, when connected to the MSTP network, we can only read the thermostat with the highest MAC address.

Observations:

• When connecting address 1, it communicates correctly.
• When connecting addresses 1 and 2, only address 2 communicates, and address 1 disappears.
• When connecting addresses 1, 2, and 3, only address 3 communicates.
• This pattern continues with the highest MAC address being the only one communicating on the Bacnet browser.
• If we disconnect the highest address, the next highest address starts communicating.

We have also attempted to resolve the issue using a Siemens PXG3.L router but encountered the same result.

Additionally, we tested by replacing the Gold thermostats with TSUB models, and they worked fine. This confirms that there are no issues with the network wiring or power supply.

Request:

Please support us in troubleshooting this issue. We have attached the datasheet of the thermostat and the address details of each thermostat for your reference.

 

How do you have the devices wired? Are you using a signal reference wire connected to the COM terminal of each thermostat?

What is the position of JP3 on all of the thermostats? Do you have EOL termination turned on or installed anywhere on the network, if so where?

What MAC address is your BACnet browser using? What MAC address is the PXG3.L router using?

It appears the thermostats support automatic baud rate detection. This can certainly cause issues, such as what you're seeing, under certain circumstances. Try configuring all thermostats to a fixed baud rate, if you haven't already.