GB2609921A - A control system and method - Google Patents

Abstract

A control system having at least one controller with a connected primary bus, at least one device connected to the primary bus, and at least one secondary bus (sub-bus in Figure 2) connected to the primary bus. Each device communicates with the controller, and each secondary bus has at least one sub-device. Communication between the controller, the/each device on the primary bus, and each sub-device uses controller area network (CAN) protocol. The primary bus may connect to the/each secondary bus using branch nodes and the/each sub-device may be a leaf node connected to an external device. The controller may assign an address to each device and each sub-device, such that each device has an address number with a single digit 1-4, and each sub-device has an address number with two digits 2.1-2.4, with the addresses being assigned automatically based upon the position of each device or sub-device on the primary and secondary buses. The control system may be used to control horticultural irrigation and may have a resilient configuration with a redundant second controller (Figure 4) or where both ends of the secondary bus are connected to the primary bus (Figure 3).

Description

Intellectual Property Office Application No G132111730.4 RTM Date January 2022 The following terms are registered trade marks and should be read as such wherever they occur in this document: Raspberry Pi Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo

A CONTROL SYSTEM AND METHOD

Description

The present invention relates to a system and method for the control of devices, and particularly the control of devices which may be used to monitor or control a commercial or industrial setting.

There is a requirement to improve the control and management of devices in a commercial industrial setting. It is often the case that devices in this type of setting are connected together using a complex wired system, or using a wireless system which may have a limitation on the number of devices which may be managed, may suffer from issues with battery life, or may suffer from interference.

In accordance with a first aspect of the present invention, there is provided a control system, the control system including at least one controller having a primary bus connected thereto, at least one device connected to the primary bus, and least one secondary bus connected to the primary bus, wherein the or each device connected to the primary bus is configured to communicate with the controller, and the or each secondary bus includes at least one sub-device, and wherein the communication between the controller, the or each device on the primary bus, and the or each sub-device uses CAN protocol.

Preferably, the primary bus connects to the or each secondary bus using branch nodes.

Conveniently, the primary bus includes at least one branch node which connects to a secondary bus and wherein the or each sub-device is a leaf node which connects to an external device.

Advantageously, the or each secondary bus is connected to at least two branch nodes on the primary bus.

Preferably, the primary bus includes at least two controllers.

Conveniently, the or each secondary bus includes a branch node. -2 -

Advantageously, the or each branch node connected to the secondary bus is in turn connected to a sub-bus including at least one leaf node.

Preferably, the sub-bus connected to the secondary bus is connected to at least two branch nodes.

Alternatively, the secondary bus is connected to at least two branch nodes.

Conveniently, a signal line is connected between the branch nodes.

Advantageously, the controller is configured to, using the signal line, assign an address to each device connected to the controller, such that the or each device connected to the primary bus is provided with an address number with a single digit, and each device connected to the or each secondary bus is provided with an address number having two digits, the first digit being the number of the device on the primary bus, and the second number being the number of the device on the secondary bus.

Preferably, the primary bus includes a power supply.

Conveniently, the power supply is connected to each of the branch and leaf nodes on the primary bus.

Advantageously, the or each branch node on the primary bus includes a power distribution arrangement, wherein the power distribution arrangement is configured to supply power to the secondary bus connected thereto.

Preferably, the power distribution arrangement further includes a switching arrangement configured to control the power supply to the secondary bus connected thereto.

Conveniently, the controller is configured to be connected to a local area network. -3 -

Advantageously, the controller is configured to expose an interface, via the local area network connection, to enable communication to and from branch and leaf nodes, including receiving real-time data from such nodes.

Preferably, the or each leaf node is a button, an actuator, a switch, or a sensor.

A further aspect of the present invention provides for a method of controlling devices, the method including the steps of providing at least one controller having a primary bus connected thereto, providing at least one device connected to the primary bus; and providing at least one secondary bus connected to the primary bus, such that the or each device connected to the primary bus is configured to communicate with the controller, and the or each secondary bus includes at least one sub-device, and wherein the communication between the controller, the or each device on the primary bus, and the or each sub-device uses CAN protocol.

Conveniently, the method includes the step of providing at least one branch node connected to the primary bus and wherein the or each sub-device is a leaf node connected to the secondary bus.

Advantageously, the method includes the step of assigning an address to each device connected to the controller, such that the or each device connected to the primary bus is provided with an address number with a single digit, and each device connected to the or each secondary bus is provided with an address number having two digits, the first digit being the number of the device on the primary bus, and the second number being the number of the device on the secondary bus.

Preferably, the method includes the step of assigning an address to each device connected to the controller is carried out automatically.

Conveniently, the addresses are assigned based upon the position of the or each device on the primary and/or the or each secondary bus.

Advantageously, the method further includes the step of providing a power management arrangement to the or each device connected to the controller. -4 -

Preferably, the method further includes the step of receiving a control signal and, in response to the control signal, switching the power stage of the or each device by way of the power management arrangement Embodiments of aspects of the present invention will now be described by way of example only with reference to the accompanying drawings in which:-Figure 1 shows an arrangement of client system and controllers in accordance with that described herein; Figure 2 shows a schematic diagram of a control system as described herein; Figure 3 shows a schematic diagram of a control system as described herein with redundancy, Figure 4 shows a schematic diagram of a control system as described herein with multiple controllers for redundancy; Figure 5 shows a high-level topology of the control system as described herein; Figure 6 shows a schematic diagram which describes an auto addressing process; Figure 7 shows a further schematic diagram which describes an auto addressing process; and Figure 8 shows a schematic diagram of a control system including power management.

The control system and method described herein provides for a multi-master, bidirectional communication system. The control system and method further provides auto-addressing functionality, which may provide automatic spatial configuration of devices within the system.

The control system, in general, comprises at least one controller configured to be connected to a client system. The or each controller may communicate with the client -5 -system via a network connection. The or each controller may expose a standard network connection such that the or each controller may communicate with the client system in a known fashion.

By way of example, the network connection exposed by the or each controller may be an RJ45 connection, operating using known network protocols. This arrangement is demonstrated in Figure 1. The controller may utilise a 100BASE-T Ethernet PHY allowing for low-latency communication between the Host and the control system. The controller may open a persistent channel over a network to effect communication.

The top-level layer of communication may be conducted over an Ethernet LAN interface for maximum data-transfer rates, while secondary communications operate on a proprietary interface, giving robustness with scope for flexible up-scaling.

A controller is required at the head of each modular installation of the control system and method described herein, and may communicate on its proprietary bus with branch nodes.

The controller may be custom hardware, using a single-board computer. In an example, this single-board computer may have similar computing power to that of a Raspberry Pi.

Further, in Figure 1, the demarcation is shown between the control system and method described herein and the systems and devices which form part of the client system to which the control system described herein would connect.

As may be seen in Figure 1, more than one controller may be connected to a client system. In order to operate the control system, a client may use an API which is exposed by the Controller device.

This API may take the form of a messaging API, which may more specifically be a JSON web API, with a bespoke messaging architecture. This messaging will be discussed in more detail later. -6 -

Turning now to Figure 2, a schematic representation of an implementation of a control system and method in accordance with that which is described herein. The control system and method as described herein may be broken down into the following types of devices: Controller node (described above), along with Branch nodes and leaf nodes as described below. These three types are shown in Figure 2.

Figure 2 includes a controller equivalent to that shown in Figure 1. The controller is the highest-level element. It is the head of the control network, which comprises a tree structure of communication buses (the control tree). This control tree may include the primary bus headed by the controller, and a set of nested sub-buses, which are denoted Sub-bus 1' and 'Sub-bus 2' in Figure 2.

As may be seen in Figure 2, both the Primary bus and the sub-buses are populated by nodes. These nodes perform some structural or input/output function. Branch nodes, denoted by square boxes in Figure 2, head a sub-bus, while Leaf nodes, denoted by circles in Figure 2, perform input/output.

The control system and method described herein is designed with the capability to automatically map its control tree, assigning location-based addresses to each node.

This automatic mapping is demonstrated in Figure 2, in which it may be seen that nodes are assigned a set of indices based on their position relative to the Controller.

In the example shown in Figure 2, the Primary bus includes Branch nodes 1, 2, and 4, along with Leaf node 3. As described above, Branch nodes 1, 2, and 4 head a sub-bus, whilst Leaf node 3 may perform input/output.

Sub-bus 4 is not shown in Figure 2, but Sub-bus 1 and Sub-bus 2 are both shown. Sub-bus 1 includes four leaf nodes. These leaf nodes may perform input/output. Sub-bus 2 includes leaf nodes 2.1, 2.2, and 2.3, and branch node 2.4, which forms the head of Sub-bus 2.4. Sub-bus 2.4 includes leaf nodes 2.4.1 and 2.4.2 which, along with leaf nodes 2.1, 2.2, and 2.3 may perform input/output. -7 -

This tree topology described above, along with the recursive structure of the control system and method provides for a large number of devices which are resilient to individual device failure.

The communication between the Controller, Branch nodes, and Leaf nodes may be effected by way of a modular nested CAN bus with automatic topological sequencing that utilises a proprietary application layer. This will be discussed in more detail below.

The node numbering described above may be considered to be the addressing of the nodes, and in some examples, this may have a maximum depth of 5 indices. The addresses are sequential and give a context-free address There is, however, scalability with the number of devices. That is to say there may be tens of thousands of devices as part of an implementation of the control system and method as described herein.

Branch nodes bridge communications between the Primary and Secondary proprietary buses, each shown in Figure 2, with each branch heading its own secondary communications bus.

Each branch may have the capability to route data packets up-and down-stream with high efficiency, utilising a unique data packet format along with optimised on-board processing to ensure low-latency, high-speed communication between primary and secondary communication buses.

In an example, around thirty branches are provided from the primary bus, with ten to fifteen leaves on each branch. In this example, one controller is provided. However, to provide resilience, multiple controllers could be used. A number of resilient configurations have been considered. A redundant controller could be used to enable switching or fail-over between controllers.

In a further example, demonstrated in Figure 3, a Branch Node could be provided at each end of a sub-bus. Referring to the example shown in Figure X, this makes all -8 -Nodes from 1.1 to 1.5 resilient to the failure of either Branch Node 1A or Branch Node 1B.

A further resilient example is set out in Figure 4, in which a Controller is placed at both ends of the Primary bus. In this example, if one Controller were to fail, there is a replacement Controller which may be brought into operation.

Turning now to leaf nodes, these serve as the endpoints of a control system installation, with the capability to interface with a multitude of devices.

Each leaf node may communicate directly with any standard communication protocol including SPI, I2C, CAN, [IN, UART, RS-232 and RS-485. Leaf nodes may respond to requests from a Host Application, while retaining the capability to initiate up-stream communications.

This may reduce response time in real-time monitoring situations, with nodes able to communicate status messages up-stream without having to wait for a status request from the Host Application. This is discussed in more detail later.

Up to 100 branch nodes may interface with a single controller, and up to 100 Leaf Nodes can interface with any branch, giving a possible total of 10,000 arbitrary devices connected to a single controller, in an example with a tree depth of 2.

The principal communication bus is based on the Controller Area Network ('CAN') physical layer, with a proprietary messaging specification allowing for efficient handling of data packets and errors.

This allows for both robust bi-directional communication over twisted-pair wiring, and multi-master bus access which allows any node to initiate communications with any other node.

CAN messaging may provide a simple means of communicating information from leaf nodes, via branch nodes, to the controller. -9 -

Each branch and node on the network may be auto-addressed by the control system. This auto-addressing aims to simplify client-side installation requirements, and can result in less rigid requirements for installer training and competency, leading to reduced installation costs and time taken.

The modularity and scalability of the control system and method described herein allows for the communication with and contact between primarily branch and leaf nodes) via a unique identifier, which may have a one-to-one relationship with physical on-site installation location.

A limited number of options exist to control this one-to-one relationship. One option includes the use of control node serial numbers at end-of-production-line, ensuring that the serial number and location of each node is meticulously logged at installation. Another option is to implement a method of dynamically allocating addresses which automatically determines the location of each installed node depending on its relationship to other nodes.

The auto-addressing feature described herein seeks to address this second approach, which in turn seeks to reduce the complexity of installation.

The use of a control system and method as described herein does not rely on using highly-skilled installers using a time-consuming method of logging installation locations of specific nodes, and also removes the administrative complexity of tracking node serial numbers from the factory to the installation site, as these are all allocated dynamically at install-time. Serial numbers can also be logged by the host application if required.

The auto-addressing feature may use an additional transmission line between adjacent nodes. This may be a twisted-pair differential signal on the primary bus (utilised for resilience against noisy industrial environments) and a single wire signal on the shorter secondary bus, which is less susceptible to external interference.

The adjacent connection between Nodes via separate transmission lines ensures that a signal can be propagated down from the controller, to each branch and leaf, -10 -allowing for accurate addressing of any node at any location within the installation site.

This concept may also be up-scaled for multi-site applications, with the host able to consolidate node address information across multiple control system installations, enabling the possibility of inter-site communications between individual nodes.

The tree structure of the control system allows the concepts of modularity and scalability to be achieved with high efficiency and low component counts.

Returning to a discussion of Figure 2, the structure of a main trunk, defined as a primary bus within the control system, and branches breaking off from the main trunk, defined as secondary buses within the control system, allows for bandwidth-efficient packet routing from any leaf node on any secondary bus, back to the root of the tree, which is defined as a controller node.

This may reduce supply-side administrative burden, allowing for a limited number of part numbers, with all parts being modular and scalable.

The tree structure also allows for flexible specification of an entire system, which can be dynamically scaled up or down as required.

Furthermore, the control system and method described herein is entirely modular, with customers able to determine the best installation layout for any required application. This allows for installation in both rigidly defined work zones, as well as dynamic and modular industrial zones.

Modularity may be achieved by ensuring device level processing is kept as basic as possible, with the host application implementing most of the required logic for specific applications. This leaves full control of the installation with the customer, allowing for client-side adjustments to be made without a consultancy requirement. This in turn reduces time taken for any client-side changes to be made.

All cabling and auxiliary equipment such as power supplies are also integrated into the control system in a modular fashion, which allows for fewer unique part numbers, reducing administrative burdens for both suppliers and customers.

The control system and method as described herein may also allow for software modularity on the client-side, with a single unified API being provided to interface with the host application.

An installation of a control system as described herein may be up-scaled with ease, by taking advantage of the modularity of the system.

Scaling the installation may be completed by removing the bus termination component of the required communications bus, connecting or removing additional nodes as required, and carrying out the auto-addressing process described below to ensure all new nodes have mapped correctly.

From a practical perspective, all modular cables are available in different lengths, with common pin-outs, allowing for complete modularity of the system.

Returning to a discussion of the auto-addressing functionality, the control system and method includes an 'address' command. The controller may initiate an addressing operation, and with reference to Figure 2, sends a command to device 1, which then addresses the next device. In an example, this may be 1.1.

Figure 5 illustrates the high-level topology of the control system in a general use case. Multiple Controllers may be connected to a host application, which may be an application or device of the end-user of the system, via a host interface, which may be a local area network (LAN). Each Controller may be independent from all others on the host interface. Each Controller may be connected to a number of Branch Nodes via a primary interface. Each Branch Node may be connected to a number of Leaf Nodes via a secondary interface. Each Leaf Node may be connected to an arbitrary device, which may be a sensor or actuator, via a device interface, which may be any industry-standard electronic interface (e.g. SPI, I2C, RS232).

-12 -Figure 6 describes the auto-addressing operation. The operation is initiated by the Controller, which sends a signal on its address line to the adjacent Node, marked Node 1. This Node responds with a CAN message containing its unique identifier. The Controller assigns the Node an ID of 1, indicating its location relative to the Controller. The Controller then instructs Node 1 to send a signal on its address line to the next adjacent Node, which responds in turn with a CAN message containing its unique identifier. The Controller assigns it an ID of 2. The process repeats until the end of the bus is reached, at which point every Node on the bus has been assigned an ID indicating its relative position on the bus.

Figure 7 describes the analogous process for auto-addressing sub-buses.

This addressing may be carried out using a line in a communications cable between nodes, and may also employ General Purpose I/O ('GPI0') between nodes.

One example of a node could be a definable button. Leaf Nodes may be small, low-cost devices which utilise embedded computing, e.g. a low-power MCU. This button may have a definable feature, and may be configured to control, in an example, a device connected to another node. This device may be a sensor, actuator, or other electrical device.

By way of an example, the definable button connected to a first Leaf node, for example node 2.3 may be used to provide an input to a sprinkler or irrigation system connected to, for example, node 2.4. This may provide manual ground-level control for a device which is also configured to be operate by way of remote computer control. The system and method described herein may be employed to automate tasks with real-world equipment, but retain a manual control element.

Leaf nodes, and the associated button/control/device/output may be custom-built for the application required.

Data may be transmitted by way of CAN-FD frames. The messages may include a standard header, followed by data in a format which is bespoke.

-13 -Diagnostic messages may be sent from Nodes to the Controller. These messages may be used to describe the node as OK/not OK.

To communicate from a leaf node to the controller, a leaf node may generate a message, and subsequently transmit the message. When the message is sent, routing 'stamps' are applied to the message at each further node that the message passes through. In an example, leaf node 2.4.2 is used.

Leaf node 2.4.2 sends a message identifying itself as '2'. This message gets passed to node 2.4, which identifies itself as '4', appending this '4' to the '2', to give a route of 4(2). When the message is processed by branch node 2, which also identifies as '2', this further '2' is appended to the message to give 2(4(2)). When the message is transmitted by branch node 2, the controller has the full address of the origin of the message. A message from the controller to a node may be routed in reverse fashion.

Firmware of nodes may be updated over the communications bus.

In addition, PDU or power management may be incorporated into the system. It may be used to monitor failures. The control system may include further a power rail and power distribution systems.

In an example, a 48v feed (or two 48v feeds, for redundancy) is/are provided. This voltage is selected because it is a safe working voltage and does not suffer from voltage drop over a distance of 50 metres.

In addition, a PDU may sit on both 48v rails and outputs 12v. Switchover/redundancy is achieved by switching between the 48v rails of the PDU. A PDU at branch level may switch, dynamically, between rails, or control the power on the branch the PDU is supplying.

There is a potential advantage in the power management aspect -that of an increase in efficiency, and a saving in power. Edge devices (those connected to leaf nodes) may be booted substantially very quickly, that is to say in the order of milliseconds. Edge devices and, in fact, entire branches may be left in a powered-down state until they are required, to increase power efficiency.

-14 -The or each PDU, controller, and branch node may need to remain powered-up to achieve this. Each sub bus may be turned off. Nodes may be configured to turn off the device to which they are connected.

The control system and method described herein is designed to be resilient and fault tolerant. All nodes are designed to be hot-swappable, which allows for efficient maintenance of the system with minimal downtime. This may allow for replacement of leaf nodes, or indeed entire installations of the control system, without affecting functionality of any other parts of the system.

This design feature results in a much lower cost in terms of both time and resource if any maintenance or adjustments to the system are required.

The ability to be hot-swapped applies to both power rails and communications busses, ensuring that any nodes not under maintenance are still able to communicate with the host application as if maintenance works were not being carried out.

Returning to a more general discussion of power distribution and management, power distribution nodes may also be implemented in the control system. These power distribution nodes may increase energy efficiency of the system depending on the ratio of required up-time to down-time. Power distribution may be achieved on branch and leaf nodes, and these solutions are also modular, with control system installations working with and without power distribution options.

Figure 8 shows an example of a PDU being incorporated between a Primary bus and a Secondary bus, with the Branch node being provided with a 48V feed, a DC to DC converter to reduce the voltage on the Branch node to 12V, and a switching arrangement to control the power supply to the Secondary bus. The Branch node may be configured to control the power supply to the Secondary bus, such that the Secondary bus may be powered down, including the Leaf nodes (and Branch nodes, if present) may be powered down when not required. This power control may be provided by the Controller, and carried out by the Branch node.

-15 -Controllable power distribution implementation is handled by the host application depending on customer requirements, and the power distribution features allow for on/off control of any branch Node, leaf node, or arbitrary device in real time.

This may allow for customer-specific application of power distribution across entire sites, ensuring that nodes are only powered on when required, and are not consuming energy when powered down.

Any acute faults, or events such as user input and sensor readings, may be transmitted upstream immediately by the Controller, and therefore the client may receive messages on the event link at any time.

On a more general level, the control system described herein is a highly modular and scalable control system for industrial applications. The system may consist of various interconnected nodes, allowing for reliable, low-latency, long distance communications with a host application.

The system is designed to be modular and can be installed in various configurations. The auto-addressing feature described above may remove client-side installation complexity, while the capability to hot swap nodes allows for efficient maintenance.

The architecture of the system is highly scalable for any application, and the two-tier tree structure communication topology complements the modularity of individual Nodes.

As the system is designed to be modular, a wide range of industrial-scale applications can be implemented via the use of the control system, including remote monitoring, asset tracking, real-time data transfer, and connected warehouse systems.

The control system and method described herein is intended to be a facilitator of arbitrary device integration into an industrial control environment, as opposed to a solution to a specific problem.

-16 -As a result almost any third-party, off-the-shelf, or custom device can be integrated into a wide range of industrial control systems via the use of the control system and method described herein. This high-level abstraction means that the control system and method is useful in any scenario where a low-latency, modular communications system is required.

Returning to a discussion of communication between the Controller and the client system, HTTP and WebSockets may be used. The use of HTTPS may give rise to structured request/response communication for the purposes of control, and the gathering of information, by the host application. WebSockets may be used to communicate upstream real-time events, Node disconnections or newly detected faults, and/or completion of asynchronous processes, such as discovery of all Nodes.

The two protocols may be well suited to these tasks, and are well-established, and may make it relatively simple to integrate into a client system with these protocols.

The communication architecture described herein may give rise to benefits which include minimised network points (a single point per controller), minimised cabling (a single tree layout), maximised modularity/extensibility, and maximised fault tolerance (node isolation).

Low bandwidth communication may also result in minimised load on the client system, and device-level processing arises as a requirement of the low-bandwidth nature of the system. the Nodes must process the raw data streams, extracting and communicating only the most important information.

Processing at a Node level may also give rise to significantly reduced performance requirements for the or each Controller in the system.

In use, the control system and method may be used to control horticulture irrigation, and this example of usage is discussed below.

The concept of a large scale commercial horticultural enterprise covering 10 acres may be addressed via the use of a control system installation.

-17 -Using the control system, a large amount of real estate can be covered by very few top-level component assemblies. A single controller may be connected to the host network, and may feed a number of branch nodes, each with their own secondary bus populated with leaf nodes.

The site is considered a large regular grid of 100 zones, with each zone measuring 20m x 20m. In this illustration each zone has a branch. Connected to each branch are multiple local leaf nodes.

Individual custom leaf node sensors measure soil temperature, soil moisture level, air temperature, air humidity and human occupancy detection.

Individual custom leaf node actuators control local irrigation, bed heaters, air heaters, roof vents and artificial lighting.

The system exposes all sensor inputs to the user over an API, and permits the user to control all actuators over the same API according to the customers control strategy, thereby maximising yield. Sprinkler, heating and lighting outputs can further be adjusted according to human operafi/ves identified in a zone.

In this illustration with 100 branches and 10 leaf nodes per branch, there are a total of 1000 leaf nodes. Installation teams follow a pre-agreed logical physical connection order for branch nodes. The automatic system addressing removes all requirements for user interaction during site configuration. Due to the physical system architecture, all 10 leaf nodes connected to a particular branch are automatically associated with each other. There is no need to capture serial numbers or go through a configuration on each leaf node.

All leaf nodes receive their power and data communications from their corresponding Branch node. API commands may be utilised to turn off the DC power output from the Branch, thereby reducing power consumption for a particular branch to OW. Power up time for an entire branch is under 5ms. As the standby current for each leaf node is circa 1W, the standby current for the leaf nodes of the entire site is 1000W. Annually, the leaf node standby power consumption is 8760kVVh. By only powering up a branch when it is required to control actuators, or read sensor values, it is -18 -possible to reduce the powered period to a maximum of 15 minutes per day. This corresponds to an annual power consumption of 91.25kVVh, an energy saving of 98.96% and a CO2 saving of approximately 2 tonnes This is a simple example of the application -many other sensors and actuators can easily be integrated into the system via additional connector interfaces on existing Leaf Nodes.

While the invention has been illustrated and described in detail in the drawings and preceding description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. Each feature of the disclosed embodiments may be replaced by alternative features serving the same, equivalent or similar purpose, unless stated otherwise. Therefore, unless stated otherwise, each feature disclosed is one example of a generic series of equivalent or similar features.

In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. Any reference signs in the claims should not be construed as limiting the scope.

Claims (24)

1. -19 -Claims 1. A control system, the control system including: at least one controller having a primary bus connected thereto; at least one device connected to the primary bus; and at least one secondary bus connected to the primary bus, wherein the or each device connected to the primary bus is configured to communicate with the controller, and the or each secondary bus includes at least one sub-device, and wherein the communication between the controller, the or each device on the primary bus, and the or each sub-device uses CAN protocol.
2. 2. The control system of claim 1, wherein the primary bus connects to the or each secondary bus using branch nodes.
3. 3. The control system of claim 2, wherein the primary bus includes at least one branch node which connects to a secondary bus and wherein the or each sub-device is a leaf node which connects to an external device.
4. 4. The control system of claim 2 or claim 3, wherein the or each secondary bus is connected to at least two branch nodes on the primary bus.
5. 5. The control system of any previous claim, wherein the primary bus includes at least two controllers
6. 6. The control system of any preceding claim, wherein the or each secondary bus includes a branch node.
7. 7. The control system of claim 6, wherein the or each branch node connected to the secondary bus is in turn connected to a sub-bus including at least one leaf node.
8. 8. The control system of claim 7, wherein the sub-bus connected to the secondary bus is connected to at least two branch nodes.
9. 9. The control system of claim 3, wherein a signal line is connected between the branch nodes.-20 -
10. 10. The control system of claim 9, wherein the controller is configured to, using the signal line, assign an address to each device connected to the controller, such that the or each device connected to the primary bus is provided with an address number with a single digit, and each device connected to the or each secondary bus is provided with an address number having two digits, the first digit being the number of the device on the primary bus, and the second number being the number of the device on the secondary bus.
11. 11. The control system of any preceding claim, wherein the primary bus includes a power supply.
12. 12. The control system of claim 11, wherein the power supply is connected to each of the branch and leaf nodes on the primary bus.
13. 13. The control system of claim 12, wherein the or each branch node on the primary bus includes a power distribution arrangement, wherein the power distribution arrangement is configured to supply power to the secondary bus connected thereto.
14. 14. The control system of claim 13, wherein the power distribution arrangement further includes a switching arrangement configured to control the power supply to the secondary bus connected thereto.
15. 15. The control system of any preceding claim, wherein the controller is configured to be connected to a local area network.
16. 16. The control system of any previous claim, wherein the controller is configured to expose an interface, via the local area network connection, to enable communication to and from branch and leaf nodes, including receiving real-time data from such nodes.
17. 17. The control system of any preceding claim, wherein the or each leaf node is a button, an actuator, a switch, or a sensor.
18. 18. A method of controlling devices, the method including the steps of: -21 -providing at least one controller having a primary bus connected thereto; providing at least one device connected to the primary bus; and providing at least one secondary bus connected to the primary bus, such that the or each device connected to the primary bus is configured to communicate with the controller, and the or each secondary bus includes at least one sub-device, and wherein the communication between the controller, the or each device on the primary bus, and the or each sub-device uses CAN protocol.
19. 19. The method of claim 18, further including the step of providing at least one branch node connected to the primary bus and wherein the or each sub-device is a leaf node connected to the secondary bus.
20. 20. The method of claim 19, further including the step of assigning an address to each device connected to the controller, such that the or each device connected to the primary bus is provided with an address number with a single digit, and each device connected to the or each secondary bus is provided with an address number having two digits, the first digit being the number of the device on the primary bus, and the second number being the number of the device on the secondary bus.
21. 21. The method of claim 20, wherein the step of assigning an address to each device connected to the controller is carried out automatically.
22. 22. The method of claim 20 or claim 21, wherein the addresses are assigned based upon the position of the or each device on the primary and/or the or each secondary bus
23. 23. The method of any one of claims 18 to 22, further including the step of providing a power management arrangement to the or each device connected to the controller.
24. 24. The method of claim 23, further including the step of receiving a control signal and, in response to the control signal, switching the power stage of the or each device by way of the power management arrangement.