Problematic MS/TP networks

Problematic MS/TP networks webinar
Problematic MS/TP networks

If you’ve ever dealt with MS/TP issues, you know they can be a massive headache. When MS/TP’s acting up, it means getting boots on the ground, clambering around in ceiling tiles, and troubleshooting section after section of network. It’s tedious, time-consuming, and frustrating.

To help relieve that frustration, we recently hosted a mini-webinar on solving major MS/TP issues. Watch our MS/TP webinar, or read on for our guide to finding, understanding, and fixing MS/TP. 

What causes MS/TP issues?

Most MS/TP networks have at least some issues. More often than not, those issues are caused by a physical wiring problem. They can also be configuration issues, but those are much more rare. Whatever the case, tokens can’t pass and that causes problems on the network.

How does bad wiring happen?

bad wiring

One of the number one issues is simply bad wiring. Maybe the electrician or subcontractor threw the network in and wasn’t paying attention. They might just not understand the network and its criticalities. So something goes wrong in the wiring, and then the tech is responsible for fixing whatever went wrong.

Flipping polarity is another big issue. Maybe when you were going from one MS/TP device to the next device, the wires inadvertently got flipped. Or, even worse, if you extended your wires through a junction box, the colour of the wire changed and you’re not sure which wire is which.

Loose wiring is extremely common. That’s an easy one to identify if you’re physically at the device: oftentimes, the second you touch the wire it will fall right out of the terminal. These loose wires can ground on any metal that’s around the device, or they can short by touching the opposite terminal. Loose wiring might be a result of bad design or loose terminals. Either the connector itself has a bad design, or vibrations cause the terminal to slowly back out. Problems with loose wiring will manifest over time, and won’t always show up right away during installation.

Wire preparation is absolutely key in MS/TP. You want to twist and terminate wires well. You want to ensure there are no loose strands. You want to make sure your insulation is stripped back far enough so you can actually connect. All these separate components might seem insignificant, but they’re critical. Miss just one and it will mess with your network.

As previously mentioned, software configuration could also be an issue. You might have duplicate device IDs or duplicate MAC addresses, or a max master that’s set too high. If you can’t bring a device up on your network or your MS/TP chain performance is not what you expect, you should start looking at the configurations for potential issues.

How do you fix it?

Finding the problem

First and foremost, you’ve got to figure out that you have an issue. Field complaints coming in from an occupied building will be one of the best ways to pinpoint problems. If the lights or the heating are erratic, occupants will let you know.

Inconsistency in general is another sign of MS/TP issues. The network’s up, the network’s down; you get some data exchange, you get none; controllers go online and offline. It’s usually not just one specific device that’s drawing attention to itself by going on and offline, it’s many different devices acting erratically.

Pinpointing the device

pinpointing bad wiring

One of the go-to ways to find the problem device is to start splitting your network. Plug into the network, cut it in half, then test one side and the other. Keep working your way down until you find the issue.

This method works, but it’s very time-consuming and intrusive. All these devices are normally in the ceiling, so might have to work after office hours to avoid disrupting occupants.

An alternative is using tools like Wireshark or Visual BACnet. Visual BACnet is an advanced visualization tool for building automation. All you need to do is capture the packets on the network through Wireshark or our capture tool, and Visual BACnet will analyze the token passing. The program has three diagnostic checks specifically for MS/TP issues, to pinpoint where tokens aren’t being passed. By looking at token disruptions, and drawing out the token roundtrips, you can pinpoint the problematic devices. Once you know where the problem is, you can start pulling on wires and checking configurations.

Fixing the issue

Track the terminations and fix them if they’re a problem. Definitely watch your terminations, because that’s likely where your issues are going to be. If all your wiring is properly terminated and connected, then start looking at your configurations.

There you have it! Hopefully MS/TP problems aren’t messing up your network, but if they are, this should help you dive in, diagnose, and fix MS/TP.

Watch our MS/TP webinar for more!

Recent Blog Posts

Think your site doesn’t have problems? Think again.

A study of two years’ worth of data found that a whopping 76% of files have significant issues. 

At Optigo, we firmly believe IT and OT teams can work together in any number of ways. Your network could be separate or converged, and you could assign responsibilities based on expertise or device type.

Every International Women’s Day (IWD) is a chance to look at how far our society has come, and how far we still have to go.

BACnet/IP predominantly communicates through broadcast messages, which are received by every device on the same network. Broadcasts are super important for discovering devices or finding and sharing new information.

OK, so we understand that BACnet is a communications protocol.  

Recent Projects

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.

Aster Conservatory Green Optigo Connect


The Aster Conservatory Green is a community comprising 352 residences across 24 low-rise buildings. The buildings use advanced surveillance and access control technology, including 40 HD video cameras and 60 FOB-access-tele-entry points for access control.



When Delta Building Automation (Australia) won the BMS Upgrade at 25 National Circuit for the Australian Trucking Association, they partnered with Optigo Networks to create a secure and robust Building Services Network (BSN). Optigo Connect more than delivered on this project with a scalable solution that restored the building network to perfection.

Optigo Connect Seattle Stadium


Optigo Connect offered a simple, cost-efficient solution for a premier Seattle-based stadium. Optigo Networks’ design improved the surveillance system to crystal clear perfection, made it dependable, and allowed the security system to scale with the addition of more than 40 16MP cameras.



Optigo Networks and OTI offered a secure and scalable solution for four data centers’ HVAC and Access Control systems throughout the United States. Optigo Connect’s performance in the first data center was so impressive, the client asked that Optigo replicate the network design for three other data centers.