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Legacy Integration: How we Connect with Your Existing Systems

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Recently our CTO Andrew Hathaway, explained how The Hark Platform integrates with legacy systems in various different industries and why flexibility of our platform is key to our product and service offering.

Here I’d like to delve a little deeper and explain how our system works from a hardware perspective, and what protocols we use.

The protocols we integrate with have huge adoption within the industrial appliance industry. This gives us a large market that can immediately see the benefits of connecting their devices to The Hark Platform. These protocols can support control of the connected devices, so we have the potential to replace their SCADA (Supervisory Control And Data Acquisition) systems.


Modbus is a serial communications protocol, that was made in 1979 by Modicon, now acquired by Schneider Electric.

The main use of Modbus is to connect industrial systems. Generally, in a configuration of one RTU (Remote Terminal Unit) as master, with other devices connected as slaves.

There are around 8 versions of the protocol specification, one for each different method of communication. We currently employ two of these, Modbus RTU & Modbus TCP/IP. Generally speaking though the protocol is the same across the wire between most of the versions with some subtle differences and/or extensions.

Modbus RTU is connected to our Hark Hub, via two-wire RS-485 cabling. We often use Modbus RTU for connecting to submeter appliances.

Modbus TCP/IP is a method in which all of the devices are connected to the same LAN (Local Area Network). With the Hark Hub connected to the same network, we can connect to Modbus TCP/IP devices by using their IP addresses. Industrial temperature control devices are often connected via Modbus TCP/IP, for example, Eurotherm’s EPC-3000 series.


BACnet stands for “Building Automation & Control network”. A lot of HVAC (Heating, Ventilation and Air Conditioning Control) systems support BACnet by default. It allows automation controllers to easily gather information from connected devices, no matter where the device is physically located.

As with Modbus, there are a range of ways to connect to BACnet, we often use the BACnet/IP variation.

Differing from Modbus, BACnet is a self-describing network. This allows you, as a protocol user, to easily gather information about all of the devices on a BACnet network.

Modbus requires you to know a devices information, and how to query for that information, for you to get a value out of the protocol. This includes knowing said devices IP address, and register information, which differs per-device.

With BACnet’s “Identify” command, devices on the network will respond and describe themselves to you, with a plethora of information.


C-Bus is another communications protocol that is used for connecting to home and building devices, for automation. C-Bus is often employed for lighting control systems, and was original made by Clipsal Integrated Systems, a company now also owned by Schneider Electric, as a proprietary protocol for their automation equipment.

The automation equipment makes it easier for industrial lighting protocols to be connected together and controlled from one source. Examples of such protocols are DALI, Digital Addressable Lighting Interface, and DSI, Digital Serial Interface. These are used for LED based lighting systems, and florescent ballasts.

As mentioned, we can now connect these separate systems together and group them, enabling us to turn the lights up, configure a schedule or setup scenes.

Large supermarkets often require minimal lighting in the morning, before customers arrive. When trading starts, a schedule will have prepared the lights and set the brightness to the correct value, ready for the day ahead.

C-Bus, like most protocols we see in this area, is a serial communication protocol. That being said, because the C-Bus interface carries power over its lines (and uses RJ-45 across the network), you can’t just connect it to a network switch. In fact, if you see a C-Bus device with it’s bright pink Ethernet cables, it’s best not to try connect a network switch or network device to it as you could ended breaking your network appliance or worse your expensive C-Bus device.

If you have any questions about any of the protocols mentioned above, feel free to get in touch, we love protocols!

Bradley Halstead
Bradley Halstead
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