The difference between fire alarm and bus system

Multi-line control is used for manual control by the host control room, which is usually not controlled by the alarm system and is controlled by humans. Utilize relays, contactors.

Finish. The multi-line is a pair of control of the fire linkage facility.

1. Point-to-point control loop.

The bus is an automatic fire alarm system.

The signal transmission line and the fire linkage system are combined into one, that is, there are detectors, manual alarm buttons, and control module loops that control the action of fire linkage facilities and accept the action return credit number in one loop. That is, the devices are connected in parallel on a single bus. It is relatively simple to use the bus system wiring.

Under normal circumstances, if the number of fire-fighting linkage facilities is relatively large and concentrated, it is more economical and reasonable to adopt the bus system.

What is the difference between the fire alarm multi-limit and the bus system? What is the difference in construction processes? How is each point connected to the fire host? What form of fire alarm system is generally used at present?

Multi-line: The circuit of the detector is relatively simple, but the disadvantages are that there are many lines, large pipe diameter, complex threading, and it is difficult to find line faults.

Bus: The two-wire system uses less wire, and the two-wire system is a technology that combines the power supply line and the signal line into one relative to the four-wire system (two power supply lines and two communication lines), and realizes that the signal and power supply share a bus. The second bus saves the cost of construction and cables, and brings great convenience to on-site construction and later maintenance.

The design and construction are convenient, so the powerbus two buses can be wired steplessly, the bus can be powered, and the communication and power supply do not need to be electrically isolated.

The bus has strong anti-interference ability and can go parallel with the mains.

Up to 256 devices can be connected at the same time.

The communication distance can reach 3000m

Hermaphroditic cabling is supported.

Support arbitrary topology routing: tree, star, bus.

No special cable requirements.

The maximum bus voltage can reach 48V

Transparent serial port protocol, compatible with the original RS485 system.

Adaptive 9600bps and 2400bps half-duplex communication.

Low-cost solution.

It can be isolated and non-isolated, so as to ensure that the electromagnetic compatibility is special. Sex.

There is a difference between the multi-line system and the bus system, whether it is in the fire alarm system or not. The multi-wire system is applied 1-to-1. The master to each slave is pulled out separately.

The bus system is used by the master to pull a group of wires out to connect all slaves. Fire alarm systems are just one part of a fire protection electronics system. There are others such as:

Fire door monitoring system, emergency evacuation indication system, combustible gas detection system and so on. Generally speaking, these systems are mainly based on the bus method, taking into account the problems of on-site construction. For example, the temperature and smoke sensing plus hand report are generally used by the fire bus, and the emergency evacuation, power monitoring and other systems will use the powerbus bus.

No matter how you use it, you can make the whole system in the form of a bus.

This fire alarm is a profiteering industry, there is no unified form of fire alarm system at all, and the interpretation of the provisions is: fire alarm system, fire automatic alarm system.

It is composed of a fire alarm host, a fire feature or early fire feature sensor, an artificial fire alarm device, and an output control device.

The sensor completes the detection of fire characteristics or early fire characteristics and transmits the relevant signals to the fire alarm host.

The alarm host completes the display and recording of the signal, and completes the corresponding output control. Lightning protection and grounding regulations for automatic fire alarm and fire linkage control system in buildings.

1. The signal transmission cables of the alarm host, linkage control panel, fire alarm broadcasting, intercom communication and other systems of the fire alarm control system should be installed at the junction of the direct lightning protection area (LPZO A) or the direct lightning protection area (LPZO B) and the first protection area (LPZ1) in and out of the building.

2. The inlet and outlet line ports of the network between the fire control room and the "119" alarm command center in the region or city should be equipped with an appropriate signal surge protector.

3. In the fire control room, an equipotential connection network should be set up, and all racks (shells), wiring ducts, equipment protection grounding, safety protection grounding, and surge protector grounding terminals in the room should be connected to the equipotential grounding terminal board nearby.

4. The metal rack (shell), metal trunking (or steel pipe), grounding trunk in the electrical shaft, and the protective grounding terminal of the junction box of the regional alarm controller should be connected to the equipotential grounding terminal board nearby.

5. The grounding of the automatic fire alarm and linkage control system should be shared. The grounding trunk should be made of copper-core insulated wire with a cross-sectional area of not less than 16 mm2, and the equipotential grounding terminal board connected to this layer (or nearby) should be laid through the pipe.

1. The cost is different.

The bus system saves wiring and cost in terms of layout, and the cost is lower, while the multi-wire system is more cumbersome and cost-effective in terms of layout.

2. The input mode of the detection signal is different from that of the controller.

The multi-wire detectors (devices) are independent of each other, and all detection signals are input in parallel to the controller. In layman's terms, it is a point-to-point connection. The bus system means that all detectors (devices) are connected to the bus in parallel, and all detection signals are serial communication with the controller.

Each detector (device) has its own unique address code.

3. Reliability is different.

Multi-line control is direct control, and the signal is manually or linked output by the alarm host, which is directly provided to the equipment; It is used for key equipment with high control reliability and good stability; The bus system, on the other hand, is usually used for less important device linkage and is slightly less reliable.

Now the alarm system of each manufacturer adopts the two-bus wiring method, that is, multiple alarm devices (smoke sensor, temperature sensor, hand report, etc.) can be connected in parallel on the two lines, according to the circuit capacity of each manufacturer, the maximum number of equipment connected by these two lines is not the same (for example: the bay circuit capacity is 242 points, other manufacturers have 96 points, there are 256 points, etc.).

The multi-line system is for the bus system, our national fire code has provisions, for some important equipment (such as: fire hydrant pump, sprinkler pump, smoke exhaust machine, etc.) must be controlled by the multi-line system, that is, each equipment must have a separate control line connected with the fire host, so that even if the line of a certain equipment is faulty or shortened by fire, it will not affect the use of other equipment.

The advantages of the bus wiring method: simple wiring, convenient construction, low project cost.

Disadvantages: Once there is a problem with a certain line, it may simply affect the equipment on a section of the line (or the entire circuit) and not work properly.

Advantages of multi-wire system: If there is a problem with one line, it will not affect the normal operation of other equipment.

Disadvantages: complex wiring, high project cost.

In the fire alarm system, the way of controlling the linkage of equipment is divided into bus system and multi-wire system.

Bus control is module control, and the 24V power supply signal or switching signal required for equipment action is provided by the bus module, which is usually used for less important equipment linkage; The advantage is that the wiring construction is convenient and the cost is lower, and the disadvantage is that the reliability is not as good as that of multi-line.

Multi-line control is direct control, and the signal is manually or linked output by the alarm host, which is directly provided to the equipment; It is used for the control of key equipment; The advantage is high reliability and good stability, and the disadvantage is that the construction workload is large and the cost is high.

1. The multi-wire system is generally the connection between the fan, pump and other important equipment and the fire alarm controller, and the common one is two to three wires, which are directly pulled from the host to the controlled equipment for direct start. The bus system is generally broadcast, strong cut, and rolling shutter. Elevators, tuyeres, sound and light, smoke temperature sensor, hand report, elimination report, fan and other equipment are connected to the host, the host has multiple circuits, all equipment is connected to one or more circuits, each device is a point, electronic code to distinguish, this is the bus.

One host has many lines and few points, which can be configured. There are many bus points, each circuit is generally about 240, can be equipped with multiple circuits, and a host can reach tens of thousands of points.

2. This is a two-core square hard wire, which is mostly used as a power cord for fire protection.

Generally speaking, the wired communication control of the constituent system can be divided into bus system, and multi-wire system or sub-limit. But it's not the same:

The bus system is that the master can be connected to multiple slaves through a line, and the slaves are given address bits, and the hosts are managed in a unified manner;

The multi-wire system (split line system) generally means that each slave is connected by a separate cable between the host and does not need an address code.

The advantage of the bus is that it facilitates multi-node wiring, saves wire, and the construction process. The advantage of the split line system is that when the wire is disconnected, it only affects the work of one node, and the others are not affected.

Therefore, when you see the wiring on the host side, you can make a basic judgment on what kind of way it is.

The bus system is that the equipment needs to be encoded, a group of lines with many devices, each device is encoded, and the host decodes;

The multi-wire system is a group of wires for a device, without coding, and the equipment is distinguished by the interface of the line.

Take fire protection as an example, the bus system, a group of lines, can be equipped with equipment such as extensions and modules within the capacity range, and multi-wire systems, an extension or module correspond to a group of lines.

It is to lead 2 wires from the alarm controller as a bus, and all detectors are hooked to this bus. The signals of each circuit are returned to the control center via the bus.

The bus system is that it branches outward from a main line, like a tree trunk;

The multi-wire system means that the signals of each loop are directly returned to the control center; For some small systems, multi-wire alarm can be used, that is, multiple lines are drawn from the alarm controller to connect each detector, and one detector has 2 lines.

The multi-line system is like a star, radiating outward from a center.

In fact, when the system is very large, for example, with 300 detection points, a combination of bus and multiline is used.

1. The bus system is: the bus system of serial communication is composed of the address line, chip selection line, data sending line, data receiving line, power line, public line, etc. of the microcomputer, and many probes are connected in parallel on about 7 common wires, and then conducted to the centralized control center through these 7 wiresWhile providing the power supply current, the bus can distinguish the output signal of each probe, and the faulty probe can also be remotely disconnected from the bus;

2. The voltage between the two buses is 24V, and the two-bus communication chip at the transmitter side outputs the digital quantity that needs to be transmitted to the two-bus in the form of current in serial output; The receiver receives the signal while receiving the power from the bus, which realizes the requirements of the common bus for power and signal.

3. The second bus is that the manufacturer connects all the alarm points through two wires and displays them in a centralized manner, which saves costs.

The two-wire system is also the bus system, the fire alarm system is not the difference between multi-line and bus, the advantage of multi-line is that a line is broken, it does not affect other equipment, but the disadvantage is that the line is fee.

There are only bus system and multi-wire system for fire alarms.

The so-called two-wire system is actually a two-wire bus, that is, the power bus and the signal bus, which still belong to the bus system.

The multi-wire system is generally only used in the fire and gas system.

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