Common BACnet MS/TP issues

Untangling typical MS/TP problems
Common BACnet MS/TP issues

It is a truth universally acknowledged, that an MS/TP network rife with problems probably has bad wiring. 

MS/TP has been a foundation for building automation for a long time. While many newer buildings are shifting towards IP and Ethernet, lots of old structures are slower to move away from their traditional, hardwired roots. Once the building is up, it’s hard to alter the network’s foundation without a serious overhaul. There’s also an “if it ain’t broke, don’t fix it” attitude in the industry, and a lot of professionals don’t see MS/TP as “broke.” 

Learn more about the differences between MS/TP, IP, and Ethernet

The downside with MS/TP, though, is that wiring is extremely finicky, and it can slowly get worse and worse over time. There are any number of problems that could arise: loose wiring, flipped polarity — you name it. And to confirm what the problem even is, you usually have to go and physically check the wiring. 

Common MS/TP problems

Problems do occasionally arise out of misconfigurations — perhaps duplicate device IDs or duplicate MAC addresses — but MS/TP issues are usually the result of bad wiring. 

There can’t be any loose strands, any untwisted or unterminated wires, any insulation that isn’t stripped back far enough. These are very small details, but even one error can cause big problems.

Read more about problematic MS/TP networks in our blog post, or watch our 10-minute webinar. 

How to solve those issues 

1. Identify the problem

Visual BACnet highlights MS/TP issues, like Longest Response Time, Average Token Roundtrip Time, and Standard Deviation of Token Roundtrip Time. Use Visual BACnet to see if you’re dealing with wiring (e.g. long Response Times or long Average Token Roundtrips), or a configuration issue (e.g. Duplicate Device IDs).  

MSTP scored checks in Visual BACnet

2. Pinpoint the device(s) 

Dig into the checks and pcap data to see which device is causing the issue. You can click on the failed check(s) to see which devices are causing the problem, and with what frequency. Hover over the entries in that failed check to view the Device ID and BACnet Address. You can also see the vendor behind the device, so you know who to call for any technical support. 

Common BACnet MS/TP issues

3. Resolve the problem(s)

In all likelihood, this digging will guide you to check your wiring because, again, that’s the most common cause of BACnet issues. While you will still have to check the physical device, at least you’ll know which one to go to, and won’t have to rip out dozens of ceiling tiles. Check the wiring and terminations, and confirm that all is connected as it should be.  

Keep an eye on your MS/TP networks now and into the future, with Visual BACnet Capture Tools for MS/TP. Install these devices on your MS/TP network and they’ll passively monitor, capture data, and send the information up to Visual BACnet for analysis. When issues arise, you’ll get an alert so you can dig in, identify problems, and quickly solve them. Learn more.  

Learn about solving common BACnet problems.

Recent Blog Posts

The consulting specifying engineer of today is venturing into totally new territory: Division 25.

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With the new 2.6.0 update for Visual BACnet, we have introduced a Linux Capture Tool. Similar to our Windows Capture Tool, now Linux users can capture BACnet IP and MS/TP traffic right from their computers.

Recent Projects

Coventry University


Chris Goodman, the Senior BMS Technician at Coventry University, had broadcast storms that were happening more and more frequently. 

Ongoing construction due to Coventry’s campus expansion meant lots of new activity, with technicians installing new devices and making network changes. Already juggling these constant additions and alterations, Goodman and his small team then had to deal with the subsequent broadcast storms. As the broadcast storms became more frequent, Goodman and his team needed a solution.

Find out how Visual BACnet helped Chris solve the broadcast storms and improve Network Health in our free case study!

Data center expansion with OTI and Optigo Connect


Stack Infrastructure is a portfolio of hyperscale computing data centers. OTI completed work on Phases I and II, and returned for the Phase III build-out of a 4-megawatt data hall and brand new central plant. The Optigo Connect network put in place in Phases I and II was expanded on this project. The team achieved quick roll-out of a large, multi-service redundant network using the Optigo OneView management interface. Going forward, the facility management team can use OneView to remotely monitor equipment, manage power usage, and meet up-time goals.

Optigo Connect MR Soluciones The Landmark


The Landmark is a sophisticated mixed-use high-rise in Mexico. The owners wanted to integrate all OT systems in the skyscraper, while maintaining separate networks for each application. The Landmark is the fourth joint project between Optigo Networks and MR Soluciones. Together, these companies provide robust services to meet any challenge.

Australian Bureau of Statistics at 45 Benjamin Way with Delta Building Automation


Delta Building Automation (Australia) had a big job renovating the Headquarters for the Australian Bureau of Statistics (ABS) at 45 Benjamin Way. The building owner wanted to improve the building’s energy use and increase their National Australian Built Environment Rating System (NABERS) score to more than 4.5 stars, out of a possible total of six. Securing the network both internally and externally was a big priority, as well.

Penn State University Optigo Networks Visual BACnet


When Tom Walker looked at Penn State University’s Navy Yard network, he saw huge issues. The system was busy and loud, to the point where the overrun network was bringing down the entire building. Because this was happening on the MS/TP network, pinpointing the problem would mean boots on the ground to segment and test the chain, piece by piece.

Penn State University Optigo Networks Visual BACnet


When Tom Walker first started working at Penn State University four years ago, there were a lot of network issues. Buildings were dropping offline. Broadcast traffic was pushing 90,000 packets per hour. Walker was on the phone almost every single night because devices were down or had to be reset.


Torre Manacar Mexico City Optigo Connect


When MR Soluciones began work on Torre Manacar, they knew they needed a flexible and scalable network infrastructure to support a wide array of integrated systems. Optigo Networks was a natural fit for the massive project, designing a robust network at a competitive cost.



Short Pump Town Center, an upscale retail center, underwent a complete renovation in 2014. The flexibility of Optigo Networks’ solution meant the retail center’s unknown final design was not a barrier to placing IP surveillance equipment in the field.



Optigo Networks connected New York-based Boulevard Mall’s security surveillance devices in December 2015, using a Passive Daisy Chain topology.

Visual BACnet tech support team


One tech support team at a manufacturer purchased an account with Visual BACnet in April 2017, for technical problems around the world.