What is the Difference Between MSTP and BACnet IP When Doing a Building Retrofit?

If you were to purchase a new mobile phone, would you buy the exact same model for the full price if the only difference was the colour? Speaking of phones, do you know anyone who still uses a landline?

When doing a building retrofit, it’s not uncommon for companies to pay full price for integrating communication technologies that don’t offer anything new and limit buildings from advancing towards the future. Bridging the gap between new and old technology is an essential aspect of retrofitting a building, which can be achieved by transitioning from an MSTP protocol to a BACnet IP protocol and APIs.

Transitioning to open, faster and higher bandwidth protocols allows building owners to continuously adapt to the technologies of tomorrow, reducing CapEX and OPEX costs while protecting the future valuation of the asset.

This article will provide a basic understanding of the difference between MSTP and IP.  Knowing the difference between these protocols can improve a building’s operations, and help to ensure an asset is ready for the future. It will also hopefully prevent ‘buyers remorse’ and ensure that the end user is investing in the latest relevant building technologies.

What exactly is MSTP?

MSTP stands for ‘Master Slave Token Passing’, it was developed over 34 years ago to allow various building devices to communicate through a system of cables. It was the most widely used communication protocol in the building automation industry. MSTP utilises RS485 cabling which runs throughout the building, connecting devices that control functions like HVAC and some lighting systems. This cabling is of a similar type that is used by old landline telephones. When building a new building, does any modern builder provide for landline telephones in the infrastructure? 

Like many other dated technologies such as the landline telephone, MSTP struggles with the requirements of today’s building technology systems. While it may meet the minimum requirements for traditional HVAC systems, the data transfer rate required to communicate with external systems such as cloud analytics is extremely taxing on an MSTP network.

Analytics is just one system that is requesting data from the HVAC network. In the future of connectivity, think about how much data is required to be moved from system to system. This is just one reason why strong and robust networks are required for the building systems of today and tomorrow.

What is BACnet IP?

BACnet IP assigns an address to a desired device, making it accessible and recognisable over a network. It allows for communication between different IP subnets and multi-campus control systems, all while providing an open-data communication platform between devices.

The architecture is ‘flat’ which means there are no global devices, and data can securely pass from device to device at a greater speed. Today’s BACnet IP network deployments allow for quick installation by using a ‘daisy-chain’, where one controller connects to the next. This is the same methodology that the building industry has used for the past 35+ years, but BACnet IP uses ethernet cabling instead of the older RS485 standard cables.

Why switch from MSTP to IP?

As mentioned earlier, MSTP limits the capabilities of the building systems and makes it more complex when integrating advanced smart building technology. 

If a building owner aimed to integrate multiple building systems under one single pane of glass, and the MSPT network was required to provide data every few seconds, we know from existing sites that the MSTP protocol would have difficulties providing the required data to the other systems in time. Below are some other misconceptions about MSTP:

Isn’t MSTP more secure than IP systems? 

On an MSTP network there is no encryption or security of data being transferred between devices, as it’s easy to connect a device to the cables and pull data off the building.

Isn’t MSTP simpler to fix? 

No, finding the issues with problems with the cables can be tricky, and it’s difficult to troubleshoot if there is an issue.

Isn’t IP more expensive? 

In today’s market, the total cost of an MSTP installation can actually cost more than the installation cost of an IP or fibre system due to the increased speed of installation for IP systems.

The immeasurable value of IP

As building owners are looking for more advanced ways to accumulate data, the increased bandwidth and speeds of IP are the most logical solution. The communication speeds of BACnet IP are faster and more reliable with a more robust bandwidth.

The BACnet IP is a faster communication protocol that meets the needs of today’s building systems. BACnet IP and BACnet Secure Connect allow for secure encrypted data to be transferred safely between devices or system to system. This protocol adds valuable capabilities to the IT infrastructure, which will increase the overall value of a building.

What is next for MSTP?

While the use of IP is on a continual upwards trend and smart technology is advancing rapidly, the older style cable communication protocols are heading towards redundancy. The rising demand for organisations to collect, process and manage data means it no longer makes sense to continue to use this slow and outdated practice.

We’re not suggesting owners remove their MSTP cables instantly. If you’re still using this protocol, we recommend transitioning slowly towards IP without affecting the architecture and operations of your building. The transition from MSTP to IP can be simple if an effective migration path is put in place, this is called a phased approach.

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