Data logging in a fire alarm system

Abstract

A data logging device 20 is provided which is compact and small enough to fit within the casing 6 of a control panel (3,fig.1) of a fire alarm system (1,fig.1). The data logging device 20 includes a data interface 23 for connection to a data connection 11 (diagnostics port) of the control panel, allowing connection to the data bus 14 thereof. The data logging device 20 is arranged to learn what detectors (4,fig.1) are in the fire alarm system and the addresses thereof. Detector values may then be securely collected from the control panel over an extended period of time, significantly longer than is possible via the typical event log in the memory 8 of the control panel. Data from the logging device 20 may be subsequently reviewed on a laptop in order to assist with identifying fire alarm conditions or faults which arise and identifying when such conditions arose, and which device was involved. The data logger device may be a single board computer (SBC) such as a Raspberry Pi® or Arduino®.

Description

Field of Invention The present invention relates to the logging of data in a fire alarm system. Background Fire alarm systems, such as the one shown in Figure 1, are installed in many premises, such as office buildings, factories, homes, and the like, and typically include a fire alarm control panel 3 (often known as control and indicating equipment, CIE), a number of detectors 4a, a number of notification appliances 4b, and wiring 2 connecting the detectors and notification appliances to the fire alarm control panel. The system might also include call points 4c and a range of other ancillary modules. In many cases, the wiring 2 which is installed is a 2-wire addressable loop, and the detectors, notification appliances, call points and other ancillary modules (hereafter called "the devices") are arranged on the loop connected across its 2 wires. Multiple loops are generally installed from the control panel, with each loop typically carrying the devices 4 to a different part of the premises. The loops typically provide power to the devices 4 on the loop, and convey instructions and data from the control panel to the individual devices, such as configuration data to all devices or an alarm signal to the notification appliances, and convey data from the devices to the control panel 3, such as a value corresponding to whatever it is that the detector is sensing. The looped arrangement means that there is some resilience to a break in an individual loop occurring during operation and that the voltage level between the wires in the loop are maintained sufficiently high to sustain all of the devices around the complete loop. A single alarm control panel can support multiple loops of addressable devices 4. Faults can arise in the fire alarm system 1 which must be identified and resolved, which involves testing the integrity of the loops, and the correct operation of the devices and the control panel. A fire alarm condition is indicated when the control panel determines that certain conditions are met by the values sent to it by the devices 4. A false alarm is raised when there is not a fire condition but the control panel processing the values indicates there is one. This false alarm could be raised for many reasons including poor detector type choice (smoke, heat etc) or by poor selection of an algorithm within the control panel which assesses the values against the criteria for a fire alarm condition. If the system reports unwanted alarm events the engineer needs to investigate. Once the cause is explained a technician can take the appropriate action. The event log contains a record of events such as fire alarm conditions or faults which arise, and identify when such conditions arose and which device was involved. Fire alarm systems do not have data storage sufficient to collect all available data over a long period of time because, in fault-free operation, an enormous amount of data would be collected which would require costly large-scale storage. Fire alarm technicians are known to connect laptop computers to control panels to collect the contents of logs and detector values over a short period of time, but this is generally limited in duration to an hour or two by the fact that the laptop must generally be supervised by a person to prevent its theft. An aim of the present invention is to permit detector values to be to be securely collected from the control panel over an extended period of time of more than a few hours, preferably extending to more than one day (24 hour period). Summary of Invention According to a first aspect of the invention, a method of logging detector values from a control panel of a fire alarm system in which the control panel includes a casing, a processor, and a data connection, the method comprises: placing within the casing of the fire alarm system a data logger device having a logger storage unit, and a data interface; connecting the data interface of the data logger device to the data connection; closing the casing of the control panel; and logging detector values from the control panel into the logger storage unit of the data logger device. The present invention permits detector values to be stored in the logger device to be logged securely over an extended period of time. In one embodiment, the method further comprises connecting a portable data memory device to the data logger device once it has logged detector values from the alarm control system. In one embodiment, the method further comprises installing logger control software on the logger storage unit before the step of logging data. Preferably, the logging of detector values involves the data logger device requesting from the control panel the most recently returned value from one of the detector devices, and to the data logger repeating the request for the most recent value of each of the other detectors. Advantageously, the method further comprises learning the addresses of the detectors by requesting a detector value of every possible address at which a detector might be present, and recording the addresses which correspond to a detector being present. In this way pre-configuration of the data logger device is not required. According to a second aspect, the invention is a control panel of a fire alarm system installed with a data logger device, wherein the fire alarm system comprises: an openable casing, a processor, and a data connection; and wherein the data logger device comprises a logger storage unit, and a data interface; wherein the data logger is located within the closed casing with the data interface connected to the data connection; and wherein the data logger device is arranged to log detector values from the control panel into the logger storage unit of the data logger device. Advantageously, the data logger comprises logger control software on the logger storage unit for managing communication with the control panel, and for managing the operation of the data logger system. Preferably, the data logger device is a single board computer. In this specification, references to a single-board computer (SBC) are to a complete, functioning computer in which its microprocessor, input / output functions, memory, and other features are all built on a single circuit board, with RAM built in and with no expansion slots for peripherals. Examples of SBCs are the Raspberry Pi, the Arduino and the ASUS Tinker Board. Brief Description of the Drawings The present disclosure will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a block diagram showing a known fire alarm system; Figure 2 is a block diagram showing a fire alarm control panel and data logger device according to the present invention; and Figure 3 is a flow diagram showing the steps involved in carrying out the present invention. Detailed Description Since the general structure of the fire alarm system of the present invention is the same as the known system shown in Figure 1, the above description of it is not repeated. Figure 2 shows the control panel 3 having a casing 6 within which are a processor 7, storage 8, a user interface 9, a loop controller 10, a data connection 11 and a power supply 12. The power supply 12 supplies power to the processor 7, storage 8, loop controller 10 and user interface 9 via power wiring 13. A data bus 14 is connected between the processor 7, storage 8, user interface 9, loop controller 10 and data connection 11. The data bus 14 permits data communication between each of those components. The processor 7 controls the operation of the control panel 3. It communicates with each of the devices 4 by instructing communications to be sent to the devices 4 via the loop controller 10. The loop controller 10 includes a number of ports for connection to the wiring 2. Communication received from the devices 4 by the loop controller 10 are communicated via the data bus 14 to the storage 8, and the processor 7 which acts according to its programming to determine any consequent actions. For example, if a detector 4a sends a communication giving a detector value which exceeds a threshold corresponding to a fire condition, the processor 7 will instruct the loop controller 10 to send an alarm signal to the notification appliances 4b, so as to alert people to the detection of a fire, and will instruct the storage 8 to record an alarm condition in the event log. Communication on the wiring takes place using a Command / Response protocol where the processor 7 directs the loop controller 10 to poll each of the devices 4 with an addressed command, and when a device receives a command addressed for it, the device 4 carries out the instruction and sends a response on the wiring 2 for the control panel 3 to receive. The command from the loop controller 10 to a device 4 could, for example, instruct it to enter data into its memory, such as configuration data, it could instruct it to send some data to the control panel over the loop, it could request an alarm status if the device is a detector 4a, or it could request a value from the device if the device is a detector, or it could instruct the device to sound an alarm if the device is a notification appliance 4b. Every device is polled about every 5 seconds. The storage 8 includes the event log which stores a record of significant events, such as an alarm condition or when a fault is identified. The log also records the time and date of the event, and the source of the event. The storage 8 also stores other data, including the values returned by the devices when they are polled by the control panel, and it is this data which the processor 7 is described above as comparing with a threshold value to determine whether a fire condition exists. Since every device 4 is polled about every 5 seconds, to avoid the collection of a very large amount of information, the value returned by a device replaces or overwrites the value returned on the previous polling event so that only the most recent value is stored. When faults arise in communication between the fire alarm control panel 3 and the devices 4 on the loop, for example, by errors in installation, or by noise, the cause can be difficult to diagnose because they are often intermittent, and because there is insufficient data. In this scenario, technicians typically rely on the event log in the storage 8 of the fire alarm control panel 3, but event logs contain a limited amount of information, and don't give the exact cause for communication failure. It has been determined that diagnosis of the cause can be aided by analysing the values returned to the control panel by the devices 4 over a longer period of time, for example for a day or a week. The user interface 9 allows for a technician or other authorised person to enter data into the control panel 3, and to view information about the status of the fire alarm system. For example, the user interface 9 will typically include a keypad and a display which is a combination of status lights and an LED screen. A data connection 11 is present on the data bus 14 to allow other devices, such as diagnostic tools, to be plugged into the system with access to the data bus 14. Since the storage 8 only retains the most recent values returned to the control panel by the devices, diagnosis of problems is constrained by the fact that values returned over a longer period are not available to a technician. To overcome this problem, and to ensure security of any data logging equipment, a data logger device 20 is used which is a single board computer, as defined above. The single board computer comprises a CPU 21, a logger storage unit 22 a data interface 23 and a second data interface 24, all of which are connected to a data bus 25. The data logger device 20 also includes a power input 26 which supplies power to at least the CPU 21 and the logger storage unit 22. In this case, the data logger device 20 is a Raspberry Pi loaded with control software stored on the logger storage unit 22 to control its operation. An essential characteristic of the data logger device is that it is very compact and small enough to fit within the casing 6 of the control panel 3. A data logger device 20 is shown in Figure 2 as being located within the casing 6 of the control panel 3 with the power input 26 connected to the power supply 12 and the data interface 23 connected to the data connection 11. Once installed, the data logger device 20 is securely located within the casing to minimise the risk of theft. The method of logging data from the control panel 3 of the fire alarm system will now be described with reference to Figure 3. Step one 31 is to open the casing 6 of the control panel 3. Step two 32 is to place the data logger device 20 within the casing 6 of the control panel 3. It might be appropriate to secure the data logger device 20 within the casing 6, for example, with zip ties. Step three 33 is to connect the data interface 23 of the data logger device 20 to the data connection 11 of the control panel 3 with a cable so that data can be passed from the data connection 11 to the data interface 23. Step four 34 is to connect the power input 26 of the data logger device to the power supply 12 within the casing 6 of the control panel 3. However, the data logger could be battery powered, in which case, this step would not be required. Step five 35 is to close the casing 6 of the control panel 3 with the data logger device 20 located securely inside. Step six 36 is the learning of what detectors are in the fire alarm system and the addresses of those detectors. This is done by the CPU 21 of the data logger device 20 sending a request to the processor 7 of the control panel for the value of a device having a first address, say Loop 1, address 001, via the data bus 25 of the data logger device 20, the data interface 23, the data connection 11 and the data bus 14 of the control panel for the current value held in the storage 8 for that device. If there is a detector at this address, the data storage 8 returns the detector value back to the data logger device 20 where that value is stored in the logger storage unit 22 together with the time and date of collection, and the identity of the device 4 that the value came from. If there is no detector with that address, the storage 8 reports this to the data logger device which ensures that no future requests are made corresponding to that address. The CPU 21 repeats this process with Loop 1, address 002 and all the other possible addresses, and logs both the values of all the sensor devices 4a, and learns which addresses to request future values about, and which to exclude. Step seven 37 of logging the values can then take place. It will be realised that, once steps one to four have been completed, the logging of data might be expected to start before the casing is actually closed. Logging is done by the CPU 21 of the data logger device 20 sending a request to the processor 7 of the control panel via the data bus 25 of the data logger device 20, the data interface 23, the data connection 11 and the data bus 14 of the control panel for the current value held in the storage 8 for a particular detector. The data storage 8 returns that value back to the data logger device 20 where that value is stored in the logger storage unit 22 together with the time and date of collection, and the identity of the detector 4 that the value came from. Some detectors have more than one sensing element, such as smoke and heat sensing elements, so more than one value might be available, in which case all of the values are stored by the data logger device. Once a value has been stored, the data logger device 20 requests the value of the next detector 4, and this is repeated until the values originating from all of the detectors has been collected and stored. It is important that the data logger device 20 doesn't put the control panel under too great a load as it must remain fully operational during the logging. For this reason, the data logger device 20 throttles its requests. One way it can do this is to request values at a frequency, for example, of X requests per second, at which it is known that the control panel is capable of achieving. An alternative is to have a timed pause following the receipt of a value before requesting the next one, say 0.2s. The reason this is advantageous is that it introduces a dynamic component to the requests because, if the control panel is under greater than average load, it will take longer to return a value, and this causes a reduction in the frequency of requests made to the control panel for values. It will be appreciated that not all of the values will be stored in the data logger device because, the frequency of value logging will generally be less than the frequency at which they are acquired by the control panel. However, enough data will be logged to make diagnosis of problems much easier, and the safe operation of the control panel will not be compromised by the logging process. The data stored will include the time / date, device type, device address, monitored values. Step eight 38 is carried out once the data logger device 20 has been operating for a long enough time that it will have connected a sufficient amount of data, and is to reopen the casing 6. Step nine 39 is to download the data from the data logger device 20. This might be done in a number of ways. A portable data memory device can be plugged into the second data interface 24 in order to download the data onto the portable data memory device so that the data can then be analysed, for example, by being plugged into a laptop computer. Alternatively, the laptop computer could be plugged directly into the second data interface 24 of the data logger 20 and download it directly. Step ten 40 is to disconnect the data logger device 20 from the control panel 3 and to remove it from the casing 6. Step eleven 41 is to close the casing. Once the data has been analysed, if a situation can be identified (a fault or cause of false alarms) based on the data which has been analysed, appropriate action can be taken. Various further modifications to the above-described examples, whether by way of addition, deletion or substitution, will be apparent to the skilled person to provide 5 additional examples, any and all of which are intended to be encompassed by the appended claims.

Claims

1. A method of logging detector values from a control panel of a fire alarm system In which the control panel includes a casing, a processor, and a data connection, and the fire alarm system includes detectors, the method comprising:5 placing within the casing of the control panel a data logger device having a loggerstorage unit, and a data interface;connecting the data interface of the data logger device to the data connection;closing the casing of the control panel; and10 logging detector values from the control panel into the logger storage unit of thedata logger device.

2. A method according to claim 1 comprising connecting a portable data memory device to the data logger device once it has logged detector values from the alarm 15 control system.

3. A method according to any one of the preceding claims comprising installing logger control software on the logger storage unit before the step of logging data.20 4. A method according to any one of the preceding claims wherein the logging ofdetector values involves the data logger device requesting from the control panel the most recently returned value from one of the detectors, and to the data logger repeating the request for the most recent value of each of the other detectors.25 5. A method according to any one of the preceding claims, further comprising learningthe addresses of the detectors by requesting a detector value of every possible address at which a detector might be present, and recording the addresses which correspond to a detector being present.30 6. A control panel of a fire alarm system installed with a data logger device, the firealarm system including detectors,wherein the control panel comprises: an openable casing, a processor, and a data connection; andwherein the data logger device comprises a logger storage unit, and a data35 interface;wherein the data logger is located within the closed casing with the data interface connected to the data connection; andCMwherein the data logger device is arranged to log detector values from the control panel into the logger storage unit of the data logger device.

7. The control panel of a fire alarm system installed with a data logger device 5 according to claim 6, wherein the data logger comprises logger control software on the logger storage unit for managing communication with the control panel, and for managing the operation of the data logger system.

8. The control panel of a fire alarm system installed with a data logger device 10 according to claim 6 or 7, wherein the data logger device is a single board computer.

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