The necessity of applying NTP time synchronization server to hospital information system
1.1.1. System overview
Clock system products used in hospital, campus and traffic engineering must be accurate, safe and reliable. On the basis of summing up the experience of clock system produced by the company and its counterparts at home and abroad for many years, we adopt the design ideas of system theory and process theory, apply the advanced communication and computer technology in the world, and adopt the distributed structure to design a kind of distributed control system with high accuracy and reliability, advanced technology and excellent quality Large area sub master clock system. The equipment in the technical proposal is supplied by the company itself, and the components and components (except for CUP chips) are used in the system. Most of the equipment and components are made in China. The design of the hardware and software is based on the principle of advanced and reliable, considering the complicated environmental conditions of each field, and the product design. The environmental differences and architectural styles of the South and North are fully considered. The exterior design and internal and external protection of the products are fully prepared and considered. In particular, the appearance design of the slave clock is coordinated with the on-site decoration design style to achieve the perfect combination of function and impression.
Clock system is an indispensable and important part of engineering system. Its main function is to provide a standard and unified time information for system staff and people, and provide unified standard time signal for other relevant operation system equipment of each department, so as to realize the time standard unification of departments and the whole network. It plays an important role in the service quality of the system.
The working principle of the clock system is that the master clock receives the time information of GPS / Beidou satellite. The master clock provides unified standard time signal for other systems through serial port and NTP Ethernet interface, so as to synchronize the time of other communication system equipment, LAN server, computer workstation and clock system, so as to realize the unified time standard of the whole network.
1.1.2. Key points of system design
① All equipment of the system can meet the requirements of continuous operation 24 hours a day.
② This system has the ability of monitoring. By setting the monitoring computer in the campus control center, it can monitor the running status of the main equipment of the clock system and the synchronization of the campus clock in real time.
③ The distributed structure is adopted in the system design. The system is composed of master clock (ZigBee wireless interface, multi-channel serial output interface equipment, NTP network timing interface), slave clock and transmission channel. The campus master clock is independent of the upper network and can control the time of the slave clock. Similarly, the NTP server can also be independent of the upper network and can provide the standard time signal to the network.
④ Network master clock generates precise time code by receiving standard time signal of upper network or GPS / BeiDou Satellite standard time signal of local station. ZigBee wireless communication interface is used to communicate with the slave clock and other systems. Thus, the time of the whole network system is strictly synchronized with the standard time of the upper network or satellite.
⑤ The promotion and whole process control of green and environmental protection design concept, the selection and use of low energy consumption components, the application of low-energy long-life luminescent materials, the use of new durable materials, and the introduction and application of advanced VLSI technology have greatly reduced the overall energy consumption of the clock system, improved the service life of the clock system, and reduced the use cost.
⑥ In order to improve the reliability of the system, the system adopts closed-loop control, isolation technology, power failure protection, software self diagnosis measures, etc., and the software and hardware design adopts large redundancy.
⑦ The design of the system follows the principles of maturity, accuracy, simplicity, reliability, easy expansion and management, so as to ensure the safety, reliability and low cost of long-term operation. At the same time, it is easy to manage and expand, and maintain the advanced nature in a certain period.
⑧ The design of the system fully considers the characteristics of high-speed rail traffic, especially the interference of electromagnetic wave generated by electromagnetic motor on the clock system. Anti electromagnetic and anti electrical interference equipment and cables are adopted, and necessary protective measures are taken.
⑨ The system can be easily expanded and upgraded, and the changes to the campus master clock system of each node will not affect the whole system.
1.1.3. System composition
188.8.131.52. System structure diagram
184.108.40.206. System function
Synchronous proofreading function:
The network master clock receives the standard time (main external clock source) from the clock source of the upper network (master clock) or the GPS / BeiDou time code signal set by the local station (standby external clock source), so as to calibrate its internal clock accuracy and keep synchronization with the upper network standard time and the local GPS / BeiDou standard time. When the network master clock fails both in the upper network and GPS / BeiDou signals, the master clock automatically switches to the master clock with stable working height.
Master clock on time: minute: second format display time; digital slave clock time: minute: second display (or optional with date display). Date display:
Master clock can display year, month, day, week, hour, minute, second and other full time scale time information, and display the operation information of loaded slave clock.
Provide standard time signal for other systems:
The master clock is equipped with NTP Ethernet interface output interface, and Ethernet (NTP protocol) interface signal is sent to other system equipment.
System hot backup function:
Master clock is composed of master clock and standby master clock, with hot backup function. When the main master clock fails, the system can immediately detect and automatically switch to the standby master clock, and the standby master clock will fully replace the main master clock. After the main master clock returns to normal, the standby master clock will immediately switch back to the main master clock.
Network master clock function:
The main and standby signal processing unit of network master clock is the central part of the whole campus clock system. Its working stability determines the reliability of the whole system to a great extent. Therefore, it is designed as a dual computer system with main and standby machines. The main and standby machines have self-test and mutual inspection functions, and can realize automatic or manual switching between the main and standby computers. The output of network master clock is digital signal, which conforms to the industry standard and ITU specifications.
(1) network master clock can display year, month, day, week, hour, minute, second and other full time scale time information.
The network master clock panel indicator displays the following information:
I. effective quantity of GPS / BeiDou data
II. Effective indication of upper network data
III. power condition
IV. display the date output by clock device in YY-MM-DD (year month day) format
V. display the output time of clock equipment in hh-mm-ss (hour minute second) format, which can be switched between 12 hours and 24 hours.
ⅵ local fault alarm indicator
The network master clock has the following alarm output,
I. GPS / BeiDou signal failure
II. Bits signal failure
III. output failure
IV. power failure
V. failure of auxiliary system
(2) the network master clock is synchronized with GPS / BeiDou or upper network standard time.
(3) the network master clock can realize the unified adjustment of time through the keyboard set on the front panel with lock.
(4) Beidou and Beidou can receive time signals. However, when the external clock source fails or the time signal is interrupted, the fax democratic master clock immediately enters the “free operation” mode after judgment and confirmation, and the process of judging the actual effect of the external clock source does not exceed 5 seconds. In the free operation mode, the network master clock generates the time information according to the last received upper network or GPS / BeiDou signal as the reference time. During the external signal interruption, the network master clock continues to work independently, uses the time signal generated by its own highly stable crystal oscillator as the time reference, and operates in the “independent operation” mode, so as to maintain the continuity of itself and its subsidiary systems. At the same time, alarm is sent to the clock system maintenance terminal and the dispatching center of Wuhan Guangzhou line.
(5) the network master clock can adjust the starting time and change the clock speed.
(6) the network master clock receives the operation status information from the campus master clock and its slave clock through the data channel provided by the transmission cable through the shunt output interface box.
(7) the network master clock has the function of setting and timing switching of daylight saving time. This function mainly considers that it can adapt to the needs of unified implementation of daylight saving time in the future. It is normally closed and can be activated immediately when necessary to avoid manual intervention.
(8) the network master clock can detect the frequency fluctuation of the city power grid in real time. When the frequency fluctuation is too large, it can send an alarm to remind the equipment management personnel to take necessary measures.
(9) the network master clock is connected with the maintenance terminal of the dispatching center or the centralized alarm network management of the monitoring center of the Ministry of railways through the standard RS232 / 422 interface to realize the monitoring of the main equipment and components of the clock system.
⑽ Through 10 standard RS422 / 485 interface, network master clock sends full time scale time signal to operation organization, passenger transport management department, campus and signal, official telephone system, special telephone system, wireless system, broadcasting system, AFC system, recording system, PIS system, signal system, MCS system and SCADA system, and other subsystems that need to be unified in time, so as to realize all communication subsystems The system time is strictly unified.
(11) the network master clock can realize the automatic switch between the master clock and the standby master clock immediately when a fault is found through the cyclic self inspection and mutual inspection of the working state of the master clock and the standby master clock, and the normal master clock and the standby master clock can also be manually switched.
(12) working time of the system: 25 years × 365 days × 24 hours. No amplifier and relay equipment are connected, and ordinary class 5 UTP transmission is adopted. The limit line distance of driving slave clock of campus master clock is 1500m (optical fiber transmission is not limited by distance).
Function of slave clock
The slave clocks of each network are connected with the campus master clock through the NTP interface and the direct cable in the point to multipoint manner to receive the synchronous time signal sent by the campus master clock, calibrate its own internal clock, and directly indicate the time information to the staff and passengers. After receiving the standard time signal, the slave clock sends back its working state to the campus master clock.
The slave clock is not directly connected to the campus power supply system, and the 220 V AC power supply is provided by the campus master clock in a point-to-point manner. By lighting the LED indicator on the clock panel, each slave clock indicates that it has received the correct control data and has synchronized with the campus master clock.
When the slave clock receives the effective control signal from the local campus master clock, the time error between the slave clock and the campus master clock shall not exceed 10 microseconds.
All slave clocks have independent timing function, which can track the work of campus master clock. When the campus master clock fails or fails to receive the synchronous time signal due to other reasons, the slave clock can still rely on its own crystal oscillator and send alarm information to the upper network or campus master clock through RS422 interface.
When the signal is interrupted, the slave clock will enter the “free operation” mode, and the LED indicator will go out. After receiving valid control data again, the slave clock will be calibrated automatically. The calibration of digital slave clock is completed within 1 second, and the longest time tracking distance of analog slave clock is 6 hours (forward and reverse time tracking is available), and it takes 6 minutes to complete time tracking at 60 times speed. Unless the slave clock fails, it is not necessary to manually adjust the display time.
The project adopts two types of slave clocks: Digital slave clock and analog slave clock. All embedded slave clocks are embedded in the guiding screen of campus platform and station hall. Windows are opened on them according to the size given by the clock system. The slave clocks are embedded in the window with closed and independent modules, and the power line and signal line are introduced separately.
All slave clocks have memory function, built-in real-time clock integrated circuit and rechargeable battery. After power failure, the real-time time data can be maintained for ten years. The digital slave clock will automatically refresh and display the correct time. The analog slave clock will automatically enter the time tracking program, automatically calculate and select the shortest path forward or backward, and run normally after catching up to the correct time at 60 times speed.
Under various light conditions (such as strong direct sunlight), all slave clocks are clearly visible.
The shell of the slave clock is made of stainless steel or aluminum and other metal materials. See the appearance drawing for the design effect of the bell cover. The appearance design meets the requirements of the specification and fully considers the visual influence of the slave clock and the slave clock box in the campus. The ergonomic factors and the overall coordination with the campus design are also considered in the case design.
The range of color selection for the bell cover is unlimited, and it can be made according to the color code required by the owner. The color selection will be decided by the owner during the design liaison.
All bell guards are equipped with shatter proof, anti reflective glass or hemp panel.
Maintenance terminal function
Each campus is equipped with a clock system monitoring and management PC, that is, a maintenance terminal, which can carry out system performance management, configuration management, fault management and security management. The monitoring software is programmed with Visual Basic 6.0 and runs on Windows XP Home operating system. The monitoring interface adopts Chinese display and pull-down menu mode, which has friendly man-machine interface, good openness and expansibility. It is convenient to add, delete and change the number of master clocks and slave clocks that need to be monitored. It is connected with the upper network through the standard RS232 / 422 interface, and has the functions of centralized maintenance and self diagnosis.
The maintenance terminal can detect the operation status of the main equipment of the railway campus level clock system in real time, display, print and archive the working status and fault status of the system, and can control the clock point-to-point in the whole line. The main monitoring and display contents include:
(1) receiving status of upper network and GPS / BeiDou signal
(2) working state of signal processing unit
(3) working state of master clock and each slave clock
(4) working state of output interface
(5) working state of transmission channel
(6) control of the whole line clock system
(7) working state of power supply
(8) basic troubleshooting principles and other help information
The monitoring terminal can also print and record the fault status and time. When the system fails, it can send out sound and light alarm to indicate the fault position. At the same time, the fault information can be transmitted to the centralized alarm terminal of customer service information platform for centralized management with customer service information system (through network card). In addition, it can also realize remote network alarm and timely transmit relevant information to the communication tools of equipment managers who are not in the fault site.
NTP server function
Network time protocol (netp) is a synchronous time protocol that serves computer clock through Internet. It provides a synchronous time mechanism, which can adjust the time allocation with the speed of light in the large and complex Internet. It uses a returnable time design scheme. Its characteristics are: the time server is a kind of distributed subnet, which can self-organization operation, hierarchical management configuration, and can synchronize the logic clock through wired or wireless mode to reach the national standard time. In addition, the server can reallocate the standard time through the local routing algorithm and time daemons.
The design of NTP brings three products clock offset, time delay and difference, all of which are associated with the specified reference clock. The clock offset represents the number of offset caused by adjusting the local clock to be consistent with the reference clock; the time delay represents the delay time between the sending message and the reference clock within the specified time; the difference represents the maximum offset error of the local clock relative to the reference clock. Because most host time servers are synchronized through other peer-to-peer time servers, each of the three products has two components: one is determined by the peer, which is relative to the reference source of the original standard time; the other is the part measured by the host, which is relative to the peer. Each part is maintained independently in the protocol, which makes error control and management of the subnet easier. They not only provide precise measurement of offset and delay, but also provide a clear maximum error range, so that the user interface can determine not only the time but also the accuracy of the time.
Industrial standard, 19 inch standard rack type, through receiving the satellite standard time signal, first synchronizes its own internal clock, and then synchronizes the computer equipment in LAN through 10m / 100M Ethernet card. The specific hardware configuration is as follows:
1. Input signal: time code: BNC or DB9
2. Output signal: 10baset / 100BaseT Ethernet interface / RJ45 for NTP
Time code: BNC or DB9
3. Management port: 10baset / 100BaseT Ethernet interface / RJ45 for management
RS-232: terminal interface for configuration
4. Network time synchronization accuracy: ntp-1-10ms over TCP / IP network
5. Environmental requirements: working temperature: 0 ～ + 50 ℃;
6. Power supply: AC 220 V ± 25%, 50 Hz ± 5%;
7. Power frequency: 50 Hz ± 5%.
8. Power: ≤ 15W
9. Mean time between failures (mfbf): ≥ 70000 hours
220.127.116.11. Equipment configuration and performance index
Equipment performance index:
Network master clock
⊙ power supply: AC 220 V ± 15%, 50 Hz ± 5%
⊙ synchronization accuracy: when receiving GPS / Beidou / upper network signal normally, the time error with upper network / GPS / BeiDou signal shall not exceed ± 1 microseconds
⊙ it can be equipped with no more than 120 level-2 master clocks and 4200 digital slave clocks
⊙ synchronous precision error of slave clock ≤ 10ms
⊙ NTP server ≤ 2ms, bits server ≤ 2ns
⊙ extensible NTP server function
⊙ the free running accuracy is better than:
After one hour operation, the accuracy is 99.998%
2. After one week operation, the accuracy is 99.9997%
⊙ GPS / BeiDou signal recovery automatic calibration completion time: 5 seconds
⊙ self crystal oscillator precision: 1 × 10－8 seconds / day
⊙ output interface: Standard RS422 interface / NTP interface
⊙ slave clock load mode: point to multipoint
⊙ transmission distance: standard communication distance of network cable
⊙ power consumption: less than 10W
⊙ ambient temperature: – 10 ℃～ + 65 ℃
⊙ relative humidity: 5% ～ 95%
GPS / BeiDou receiver
⊙ number of tracking satellites: ≥ 6 satellites tracking at the same time
⊙ timing accuracy: 0.1s/year
⊙ interface mode: Standard RS-422 interface
⊙ antenna feeder length: 30m
⊙ antenna: equipped with lightning protection device, waterproof and anti-corrosion, with protection level no less than IP65
⊙ signal transmission distance: 100M
⊙ power supply: AC220 V ± 20%, 50 Hz ± 5%
Single side digital slave clock
⊙ display time, minute, day, and week.
⊙ support synchronous public and private network NTP time server.
⊙ support countdown display time.
⊙ the clock display can be turned off by remote software to reduce energy consumption.
⊙ the brightness software of each display module of the layout can be adjusted to ensure that the LED brightness of the display panel is symmetrical.
⊙ the clock automatically switches the addresses of main and standby NTP time servers.
⊙ clock software can be upgraded online.
⊙ digital tube pen end failure automatic scanning alarm.
⊙ support networked batch management
⊙ timing accuracy: 0.5 s / day
⊙ working power supply: AC 220 V 50 Hz
⊙ working temperature: – 20 ~ 70 ℃
⊙ dimensions: 70 * 30 * 5cm; 70 * 19 * 5cm;
⊙ LED display unit luminous intensity: ≥ 200cd / m2
⊙ contrast: ≥ 10:1
⊙ visual angle of LED display: ≥ ± 65 degrees
⊙ LED display MTBF: ≥ 50000 hours
⊙ independent timing accuracy: ≤± 0.5 s / day
⊙ environmental requirements: working temperature – 40 ～ + 50 ℃
NTP network time server
⊙ input signal: time code: BNC or DB9
⊙ output signal: 10baset / 100BaseT Ethernet interface / RJ45 for NTP
Time code: BNC or DB9
⊙ management port: 10baset / 100BaseT Ethernet interface / RJ45 for management
RS-232: terminal interface for configuration
⊙ network time synchronization accuracy: NTP on TCP / IP network: 1-10ms
⊙ environmental requirements: working temperature: 0 ～ + 50 ℃;
⊙ power supply: AC 220 V ± 25%, 50 Hz ± 5%;
⊙ power frequency: 50 Hz ± 5%.
Power: ⊙ 15W
⊙ mean time between failures (mfbf): ≥ 70000 hours
Detailed description of equipment configuration
A NTP clock server is set in the cabinet of each network communication control room (machine room), and the slave clock display screen is set in the hall, corridor, channel and other eye-catching places of other departments and inpatient houses; NTP clock server equipment includes NTP Ethernet output interface, GPS / BeiDou signal receiving processor and network interface signal for synchronization of slave clock display screen.
The detailed description is as follows:
Brand and model
Describe the configuration
GPS network master clock
GPS satellite is used as clock source, 4-channel NTP network interface (RJ45) is output for computer network clock synchronization, 2-way RS232 serial port, accuracy of 1-10ms, dual power redundancy backup, rack design, 30 meter antenna, client software, antenna bracket and other accessories;
Network clock screen
5 “nixie tube / power module / display time / minute / second / network module
Network clock screen
2.3 and 5 inch nixie tube / power module / display date, day, week, hour, minute, second / network module