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Round-Up: How to Solve BACnet Issues

How to solve BACnet problems
Over the years, we’ve dug into solutions for the most common problems we see on BACnet networks: everything from MS/TP issues to Global Who-Is broadcasts, duplications, and circular networks. Now, we’re rounding up all that info!

Over the years, we’ve dug into solutions for the most common problems we see on BACnet networks: everything from MS/TP issues to Global Who-Is broadcasts, duplications, and circular networks. Now, we’re rounding up all that info in these handy BACnet troubleshooting video tutorials!

You can check out our full guides in the list of links below, and scroll through for our recaps and videos.

  1. Fixing the most common MS/TP Issues
  2. Resolving problematic Global Who-Is
  3. Finding Duplicate Device IDs
  4. Detecting and solving Circular Networks
  5. Identifying and troubleshooting Duplicate BBMDs
  6. Finding and solving Duplicate Networks

1. Fixing problematic MS/TP networks

MS/TP networks are notoriously difficult. If you’ve got one, you’ve probably got problems.

In very rare cases, the issues might be caused by a misconfiguration, but the odds are that physical wiring is behind it all. Either way, the tokens aren’t passing and you’ve got a slow or unresponsive network. You’ll have to narrow in on the issue, pinpoint the source, and fix it.

Check out our mini-webinar to learn about solving MS/TP networks!

2. Resolving problematic Global Who-Is

Global Who-Is requests help you make sure all your devices are online. If they happen too frequently though, the system can get completely overloaded.

Big spikes in activity are a common sign of Who-Is problems. You can visualize your traffic on the home screen of Visual BACnet, with the BACnet traffic in green. In this example, the sudden spikes are a good sign that something’s wrong.

How to solve BACnet problems global who-is

In the Who-Is Checks, we can see that there are 46 packets with Global Who-Is in this 20-minute capture, and one source device is sending a Global Who-Is every minute. That’s way too much! Especially on a large system, this can overwhelm the network and cause delays.

If you change that configuration, it should put your broadcast problems to rest.

How to solve BACnet problems global who-is

3. Finding Duplicate Device IDs

You need unique device IDs on your network, but it’s hard to keep track of them! You might end up with duplicates because of default settings, changes in the system, or incorrect programming. Finding the root of these Duplicate Device IDs can be super challenging, but we’ve got ways to help.

Visual BACnet spots duplications, so you can drill down and find the devices with conflicting IDs.

How to solve BACnet problems Duplicate Device ID
How to solve BACnet problems Duplicate Device ID

By clicking on the “Duplicate Device ID” row, you can find which device ID is used by more than one device, and drill down to find the SNET and SADR.

4. Detecting and solving Circular Networks

A Circular Network means you have two or more routes to one controller. Any message transmitted to the network will continue to be transmitted over and over. That causes so much traffic that the network becomes clogged, and the controller gets so busy servicing the network that it can’t do anything else. Your controller might not be reachable, there might be reduced network bandwidth, and the BMS could be functioning slowly, among other things.

Got a Circular Network? Watch our 10-minute webinar to find out how to fix it!

5. Identifying and troubleshooting Duplicate BBMDs

A BACnet Broadcast Management Device (BBMD) sends messages from one device on a subnet to other subnets, where the message gets rebroadcast. A Duplicate BBMD means that multiple devices on the same network are set as BBMDs and send out the same messages. It’s a broadcast overload! These BBMDs can increase the amount of traffic to dangerous levels and can bring down the network entirely.

Find out how Visual BACnet helps you spot BBMD issues and fix them, in our mini-webinar!

6. Finding and solving Duplicate Networks

Duplicate Networks happen when there are multiple BACnet routers sending traffic to the same network. You can only have one router per segment, so each router needs a unique network number. When those numbers get duplicated, you end up with double the routers sending traffic. This can get really complicated, but the good news is that it’s a logical network problem and not a physical one.

Check out our guide to solving duplicate networks!


Enjoyed the advice? Download our PDF guide to take this on the go! 

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