1. The range of monitoring fire doors is not sufficient At present, many engineering projects only monitor the normally open fire doors installed in buildings, control the closure of normally open fire doors after confirming a fire, and receive feedback signals on the closure of fire doors, without monitoring the closure status of normally closed fire doors. Through research on the application of fire doors in engineering projects, it was found that the problem of fire doors not being able to close properly due to damage to door closers and sequencers is quite prominent. Due to the lack of necessary monitoring measures, fire safety management personnel are unable to timely grasp the problems that exist on site, resulting in the inability to maintain problematic fire doors in a timely manner, thereby affecting the effectiveness of fire doors in firefighting. Therefore, in practical engineering design, the monitoring range of the fire door monitoring system should include all normally open and normally closed fire doors installed on the building evacuation routes. 2. Adopting fire alarm controller or fire linkage controller In practical engineering design, there is a phenomenon of using fire alarm controllers or fire linkage controllers to replace fire door monitors. The current standard GB4717-2005 "Fire Alarm Controller" stipulates in Article 4.2 that the input signals monitored by the controller, except for fire alarm and fault signals, should be managed as supervisory signals. If a fire alarm controller is used instead of a fire door monitor in actual engineering design, the fault signal of normally closed fire doors opening should be managed as a supervisory signal. According to the standard GB4717-2005 "Fire Alarm Controller" 5.2.6.2, when there is a supervision signal input, the controller should emit supervision alarm sound and light signals that are significantly different from the fire alarm signal within 100 seconds, and the sound signal can only be manually eliminated. Due to the fact that the normally closed fire doors used in practice also allow personnel to pass through, when using a fire alarm controller to monitor the working status of the fire doors, once the normally closed fire doors are opened, the fire alarm controller should emit a supervisory alarm sound and light signal, and this sound alarm signal must be manually silenced by humans to be released. The on duty personnel in the fire control room will continuously handle the silencing of the sound alarm signal, which seriously affects the normal work of the on duty personnel. According to standard GB29364-2012 "Fire Door Monitor" 4.3.1.9, the monitor should have a fire door fault status indicator light. When the fire door is in a fault state, the indicator light should light up and emit an audible and visual alarm signal. The sound pressure level of the sound signal (1m in front) should be between 65-85dB, and the fault sound signal should be prompted at least once per minute, with a duration of 1-3 seconds each time. When the normally closed fire door is closed, the fault state of the fire door is eliminated, the fire door monitor is in normal monitoring state again, and the fault sound signal prompt sound is released. That is to say, the provisions on the sound signal of fire door faults in the standard GB29364-2012 "Fire Door Monitor" are determined based on the special functional requirements of the fire door monitoring system, which is more in line with the needs of practical engineering applications. According to the requirements of the fire automatic alarm system product architecture, the fire linkage controller can only be connected to on-site components related to fire linkage control. Due to the fact that the closure information of normally closed fire doors does not fall within the scope of fire linkage control, the fire linkage controller cannot be connected to the monitoring module used to monitor the closure status of fire doors. If a fire linkage controller is used instead of a fire door monitor in the engineering application process, according to the provisions of Article 4.2.2.5 of the current standard GB16806-2006 "Fire Linkage Control System", once the normally closed fire door is opened, the sound alarm signal emitted by the fire linkage controller also needs to be manually silenced to be released, which also affects the normal work of the on duty personnel in the fire control room. As a dedicated system for monitoring the working status of building fire doors, the interface display of the fire door monitor can more intuitively reflect the usage of the fire door. A single control function can achieve reliable control of normally open fire doors. At the same time, the proprietary functions of the fire door monitor are more in line with the actual needs of fire safety management work. Therefore, in practical engineering design, dedicated fire door monitors should be selected instead of using fire alarm controllers or fire linkage controllers as substitutes. 3. The selection of the fire door monitoring system does not meet the requirements of the fire access system There is a phenomenon in some engineering designs where on-site components such as the fire door electromagnetic release device, normally closed fire door magnetic switch, and normally closed fire door electric door closer are not connected according to the matching requirements of the fire door monitor in the type inspection report. The performance inspection of the fire door monitor is completed by connecting on-site components such as electromagnetic release devices, door magnetic switches, or electric door closers claimed by the manufacturer. In the type inspection report of the fire door monitor product, detailed descriptions are provided for the on-site components connected to the fire door monitor. Due to the different electrical parameters of electromagnetic release devices for fire doors, magnetic switches for normally closed fire doors, and electric door closers for normally closed fire doors produced by different manufacturers, the installation of untested on-site components in actual engineering can affect the reliability and stability of the fire door monitoring system operation. Therefore, in the actual engineering design process, it is necessary to select on-site components such as electromagnetic release devices, door magnetic switches, or electric door closers that have passed type inspection according to the compatibility requirements of the fire protection product access system and fire automatic alarm system, and based on the matching requirements of the product inspection report. In some engineering designs, fire door monitors are installed on site, and centralized display devices that have not been tested or whose technical performance does not meet the standard GB29364-2012 "Fire Door Monitor" are installed in the fire control room to centrally display the working status of the fire door monitor. According to Article 6.11.1 of the standard GB50116-2013 "Code for Design of Automatic Fire Alarm Systems", the fire door monitor should be installed in the fire control room. If no fire control room is set up, it should be installed in a manned location. Therefore, in the actual engineering design process, regardless of the selected fire door monitoring system architecture mode, fire door monitors that have passed type testing should be installed in the fire control room to centrally monitor all fire doors, and other devices should not be used as substitutes. 4. Misconceptions in programming linkage control logic The programming of the linkage control logic for some engineering fire door monitoring systems is too complex, requiring the fire alarm controller to communicate with the fire door monitor according to a specific communication protocol and determine the range of fire door closure based on the alarm situation of the fire detector, which brings certain difficulties to the specific implementation of the project. The fire doors installed in buildings should be able to close automatically in the event of a fire, which is the basis for programming the linkage control logic of the fire door monitoring system. Due to the high uncertainty of the development trend of building fires, after confirming the fire, all normally open fire doors installed in the building should be closed to play a role in fire separation. Therefore, in the specific programming design of the linkage control logic of the fire door system, it is recommended to use the alarm signals of two independent fire detectors in a specific fire compartment or one fire detector and one manual alarm button as the linkage trigger signal of the system. The linkage control signal is sent from the fire linkage controller to the fire door monitor, and the linkage control logic programming design method is used for the linkage control of all normally open fire doors set in the building to be closed by the fire door monitor.