CN109167667B - Sensor data acquisition and transmission system and method based on PTP synchronization - Google Patents
Sensor data acquisition and transmission system and method based on PTP synchronization Download PDFInfo
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- CN109167667B CN109167667B CN201811089362.7A CN201811089362A CN109167667B CN 109167667 B CN109167667 B CN 109167667B CN 201811089362 A CN201811089362 A CN 201811089362A CN 109167667 B CN109167667 B CN 109167667B
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- H04L67/00—Network arrangements or protocols for supporting network services or applications
- H04L67/01—Protocols
- H04L67/10—Protocols in which an application is distributed across nodes in the network
- H04L67/1095—Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
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- H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
- H04J3/0658—Clock or time synchronisation among packet nodes
- H04J3/0661—Clock or time synchronisation among packet nodes using timestamps
- H04J3/0667—Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays
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Abstract
The invention provides a sensor data acquisition and transmission system and method based on PTP synchronization, switches are connected in series, large-scale expansion can be realized according to specific application scenes, the number of the switches connected in series can be customized, the number of acquisition nodes connected with each switch can be customized, the number of sensor channels which can be acquired by each acquisition node can be customized, the array length is not limited, the process is simple, and the number of cables is small; by adopting a PTP synchronization protocol, the synchronous sampling of the data of the ultra-far distributed sensors is realized, and the synchronous acquisition precision is high; by adopting a gigabit Ethernet transmission and gigabit Ethernet transmission architecture, the transmission band is wide, long-distance transmission can be realized, and the data throughput is high; by using the Poe Ethernet power supply technology, the service data, the synchronous message and the power supply are transmitted by adopting an Ethernet cable, so that the structure of an acquisition and transmission system is simplified; the length of the acquisition array of the whole device is not limited, and high-precision synchronous acquisition and transmission of each acquisition node is realized during large-scale sensor array acquisition.
Description
Technical Field
The invention relates to the field of data acquisition and transmission, in particular to a sensor data acquisition and transmission system and method based on PTP synchronization.
Background
The distributed data acquisition and transmission technology is widely applied, and the most typical application scenes comprise data acquisition and transmission of a military linear array sonar wet-end distributed hydrophone, data acquisition and transmission of a super-large-scale multi-cable multi-detector for offshore oil exploration, a deep-sea thin cable sonar acquisition and transmission detection system and the like. The drawbacks of conventional and existing distributed data acquisition and transmission systems are summarized as follows: firstly, the traditional data acquisition and transmission technology usually adopts architectures of RS485 bus, ATM transmission, custom LVDS transmission, Ethernet plus RS485 and Ethernet plus LVDS, and the architectures have difficult engineering application, backward performance and poor reliability; secondly, the synchronization mode is backward, and the synchronization mode in the prior art mostly adopts a mode of adopting an extra certain communication protocol and using an extra cable to transmit a public system main clock node and a synchronization pulse, or adopts a mode of using serial data clock recovery to cooperate with command delay compensation to realize small-scale synchronous acquisition. The synchronization precision is deteriorated along with the enlargement of the system scale, the system does not have the expansion extensibility of a large-scale system, is complex to realize, needs additional software and hardware cooperation, causes adverse effects on the system reliability, and is limited to be applied in the fields of military sonar and seismic petroleum exploration with extremely strict requirements on the reliability; thirdly, the prior art does not have the data transmission capability of a super-large scale system, and the data throughput and the transmission distance are limited; in the prior art, service data, synchronous signals, clocks and power supplies are transmitted by adopting independent cables, the number of cables in the whole system is large, the connection relation is complex, the process is complex to realize, and the system reliability is adversely affected. A sensor data acquisition and transmission system and method based on Ethernet PTP synchronization, which has strong reliability, large-scale expansion, large throughput and high synchronization precision, are needed.
Disclosure of Invention
In view of this, the invention provides a sensor data acquisition and transmission system and method based on ethernet PTP synchronization, which are strong in reliability, large in scale expansion, large in throughput, and high in synchronization precision.
The technical scheme of the invention is realized as follows: on one hand, the invention provides a sensor data acquisition and transmission system based on PTP synchronization, which comprises a plurality of sensors, a plurality of acquisition nodes, a plurality of switches, a computing center, a master clock node and a slave clock node;
the acquisition node comprises an A/D conversion chip and a crystal oscillator subjected to PTP synchronization taming;
the working clock of the A/D conversion chip is from the crystal oscillator which is synchronously acclimated by PTP;
the master clock node is a computing center or an acquisition node, and the rest acquisition nodes are slave clock nodes;
the acquisition nodes exchange messages with the master clock node through a PTP (precision time protocol), each acquisition node locks the master clock node, and each acquisition node uploads service data to the computing center through a TCP/IP (transmission control protocol/Internet protocol);
the computing center is in signal connection with an exchanger through a gigabit Ethernet transmission line, the exchanger is connected with the exchanger in series through the gigabit Ethernet transmission line, the exchanger is in signal connection with the acquisition nodes through the gigabit Ethernet transmission line, and the sensors are in signal connection with the acquisition nodes through analog differential transmission lines.
On the basis of the technical scheme, preferably, the calculation center sets the starting time and the stopping time of data acquisition, and adjusts the sampling frequency, the working frequency and the gain;
the starting time is the sum of the current time and the preset delay time;
and the computing center issues the starting time and the sampling frequency configuration to each acquisition node through a reliable transmission protocol.
On the basis of the technical scheme, the Ethernet backup transmission line also comprises a gigabit Ethernet backup transmission line;
ten-gigabit Ethernet backup transmission lines are adopted between the computing center and the switch and between the switches.
Further preferably, the device also comprises an isolated power supply with a wide range of 36V-72V;
the switch adopts an isolated power supply with a wide range of 36V-72V to supply power, and adopts a network power supply Poe technology to supply power to the acquisition nodes.
On the basis of the technical scheme, preferably, the switch comprises a plurality of tera optical interfaces and a gigabit electrical interface;
the exchanger is a transparent clock node in PTP synchronization and is a power supply device Pse in Poe technology for supplying power to the acquisition node;
the collection node is a boundary clock node in PTP synchronization and is a powered device PD in Poe power supply technology.
On the other hand, the invention provides a sensor data acquisition and transmission method based on PTP synchronization, which comprises the following steps:
s101, building a system framework that a computing center is in signal connection with an exchanger through a gigabit Ethernet transmission line, the exchanger is connected with the exchanger in series through the gigabit Ethernet transmission line, the exchanger is in signal connection with a plurality of acquisition nodes through the gigabit Ethernet transmission line, and the acquisition nodes are in signal connection with a sensor through an analog differential transmission line;
s102, each acquisition node comprises an A/D conversion chip and a crystal oscillator which is subjected to PTP discipline, the working clock of the A/D conversion chip is derived from the crystal oscillator which is subjected to PTP synchronous discipline, a main clock node is set as a calculation center or one acquisition node, the rest acquisition nodes are slave clock nodes, each acquisition node independently exchanges messages with the main clock node through a PTP protocol, all the acquisition nodes lock the main clock node, after the acquisition nodes lock the main clock node, the phase and the frequency of the working clock of each acquisition node are synchronous with the main clock node, and after synchronization, each acquisition node continuously performs message interaction with the main clock node, and dynamic time synchronization is maintained;
s103, setting starting time for starting data acquisition by the acquisition nodes, adjusting sampling frequency by the computing center, and sending the starting time and the sampling frequency configuration to each acquisition node through a TCP/IP protocol;
s104, after receiving the starting time and the sampling frequency configuration, each acquisition node continuously compares the starting time with the local time, when the starting time is equal to the local time, the A/D conversion chip is immediately controlled to start to acquire data by controlling the low level of the SYNC _ IN pin of the A/D conversion chip, the A/D conversion chip of each acquisition node simultaneously starts to acquire data, and the acquired data are uploaded to a computing center through a TCP/IP protocol.
On the basis of the technical scheme, preferably, the switch in the S101 adopts an isolated power supply with a wide range of 36V-72V to supply power, and adopts a network power supply Poe technology to supply power to the acquisition node.
Still further preferably, the switch comprises several tera optical interfaces and gigabit electrical interfaces;
the exchanger is a transparent clock node in PTP synchronization and is a power supply device Pse in Poe technology for supplying power to the acquisition node;
the collection node is a boundary clock node in PTP synchronization and is a powered device PD in Poe power supply technology.
On the basis of the technical scheme, preferably, in the step S101, ten-gigabit ethernet backup transmission lines are adopted between the computation center and the switch and between the switch to form backup links;
the backup link is accomplished by configuring the switch chip internal status register.
On the basis of the above technical solution, preferably, the starting time in S103 is the sum of the current time and the preset delay time.
Compared with the prior art, the sensor data acquisition and transmission system and method based on PTP synchronization have the following beneficial effects:
(1) by connecting the switches in series, the system can be expanded in a large scale according to specific application scenes, the number of the switches in series connection can be customized, the number of acquisition nodes connected with each switch in a hanging mode can be customized, the number of sensor channels which can be acquired by each acquisition node can be customized, wiring can be reduced, and the system can be applied to military linear array sonar underwater acoustic sensing data acquisition and transmission, large-array-scale marine petroleum multi-cable multi-channel seismic exploration systems and deep sea acquisition transmission detection systems, wherein the traditional acquisition transmission systems cannot be well adapted;
(2) clock signal synchronization of each acquisition node is realized by adopting a PTP synchronization protocol, and high-precision synchronous acquisition of all sensors is realized based on an Ethernet PTP synchronization network;
(3) the working clock of the A/D conversion chip in the acquisition node is from the crystal oscillator after PTP discipline, so that the problems of increased routing and unreliable signal quality caused by the fact that the whole distributed acquisition system uses and transmits a unique main clock node signal through other protocols can be avoided;
(4) by adopting a gigabit Ethernet transmission and gigabit Ethernet transmission architecture, the method has the advantages of high transmission performance, wide transmission bandwidth, unlimited array length, simple process, less cables, capability of long-distance transmission, super-large-scale system data transmission capability and high data throughput;
(5) the Poe Ethernet power supply technology is used for providing power for the acquisition nodes, the acquisition node service data, the synchronous signals, the clock and the power are transmitted by Ethernet cables, the acquisition nodes can be used independently or in a small scale in a plug-and-play mode, a large-scale acquisition and transmission system can be rapidly formed, the structure of the acquisition and transmission system is simplified, and the reliability of the system is improved;
(6) the Ethernet carries out centralized management on all the acquisition nodes and adopts a TCP/IP protocol, thereby improving the transmission reliability and ensuring that data is not lost;
(7) the length of the whole collection array of the whole device is not limited, and high-precision synchronization of all collection nodes is realized during large-scale sensor array data collection application.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a structural diagram of a sensor data acquisition and transmission system based on PTP synchronization according to the present invention;
FIG. 2 is a structural diagram of a sensor data acquisition and transmission system based on PTP synchronization according to the present invention;
FIG. 3 is a flow chart of a sensor data acquisition and transmission method based on PTP synchronization according to the present invention;
FIG. 4 is a graph showing the relationship between the second pulse of the acquisition node and the master clock node in the PTP synchronization-based sensor data acquisition and transmission method of the present invention;
FIG. 5 is a schematic diagram of sampling of each acquisition node of the sensor data acquisition and transmission method based on PTP synchronization according to the present invention;
FIG. 6 is a flowchart of a method for setting a preset time according to a first embodiment of the present invention;
FIG. 7 is a network structure diagram of a default state system according to a fifth embodiment of the present invention;
fig. 8 is a network structure diagram of an abnormal state system according to a fifth embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The first embodiment,
As shown in fig. 3, the sensor data acquisition and transmission method based on PTP synchronization of the present invention includes the following steps:
s101, building a system framework that a computing center is in signal connection with an exchanger through a gigabit Ethernet transmission line, the exchanger is connected with the exchanger in series through the gigabit Ethernet transmission line, the exchanger is in signal connection with a plurality of acquisition nodes through the gigabit Ethernet transmission line, and the acquisition nodes are in signal connection with a sensor through an analog differential transmission line;
s102, each acquisition node comprises an A/D conversion chip and a crystal oscillator which is subjected to PTP discipline, the working clock of the A/D conversion chip is derived from the crystal oscillator which is subjected to PTP synchronization discipline, a master clock node is set as a calculation center, the rest acquisition nodes are slave clock nodes, each acquisition node independently performs message exchange with the master clock node through a PTP protocol, all the acquisition nodes lock the master clock node, after the acquisition nodes lock the master clock node, the phase and frequency of the working clock of each acquisition node are synchronous with the master clock node, and after synchronization, each acquisition node continuously performs message interaction with the master clock node, and dynamic time synchronization is maintained;
s103, setting starting time for starting data acquisition by the acquisition nodes by the computing center, wherein the starting time is the sum of the current time and preset delay time, and distributing the starting time and the sampling frequency to each acquisition node through a TCP/IP protocol;
s104, after receiving the starting time and the sampling frequency configuration, each acquisition node continuously compares the starting time with the local time, when the starting time is equal to the local time, the A/D conversion chip is immediately controlled to start to acquire data by controlling the low level of the SYNC _ IN pin of the A/D conversion chip, the A/D conversion chip of each acquisition node simultaneously starts to acquire data, and the acquired data are uploaded to a computing center through a TCP/IP protocol.
In this embodiment, the computing center is set as a master clock node, and each acquisition node is a slave clock node. The method for locking the master clock node by the acquisition node comprises the following steps: the master and slave clock nodes interact with each other to synchronize the message and record the receiving and sending time of the message, the round-trip total delay between the master and slave clock nodes is calculated by calculating the round-trip time difference of the message, if the network is symmetrical, namely the transmission delays in two directions are the same, half of the round-trip total delay is one-way delay, the one-way delay is the clock deviation between the master and slave clock nodes, and the slave clock node adjusts the local time according to the deviation, so that the synchronization with the master clock node can be realized.
As shown in fig. 6, in step S103, the method for measuring the preset delay time includes the following steps:
s201, the master clock node sends a Sync message to the slave clock node and records the sending time t1, and the slave clock node records the receiving time t2 after receiving the message;
s202, after the master clock node sends a Sync message, a Follow _ Up message carrying t1 is sent;
s203, the slave clock node sends a Delay _ Req message to the master clock node, the Delay _ Req message is used for initiating the calculation of reverse transmission Delay, the sending time t3 is recorded, and the master clock node records the receiving time t4 after receiving the message;
s204, after receiving the Delay _ Req message, the master clock node replies a Delay _ Resp message carrying t 4.
At this time, the slave clock nodes have four time stamps of t1 to t4, so that the total round-trip delay between the master clock node and the slave clock node is calculated to be [ (t2-t1) + (t4-t3) ], and in the embodiment, the time synchronization network is symmetrical, so the one-way delay between the master clock node and the slave clock node is [ (t2-t1) + (t4-t3) ]/2. Thus, the clock skew of the slave clock node relative to the master clock node is: offset ═ (t2-t1) - [ (t2-t1) + (t4-t3) ]/2 ═ t2-t1) - (t4-t3) ]/2.
Example II,
As shown in fig. 3, on the basis of the first embodiment, the present invention provides a sensor data acquisition and transmission method based on PTP synchronization, including the following steps:
s101, building a system framework that a computing center is in signal connection with an exchanger through a gigabit Ethernet transmission line, the exchanger is connected with the exchanger in series through the gigabit Ethernet transmission line, the exchanger is in signal connection with a plurality of acquisition nodes through the gigabit Ethernet transmission line, and the acquisition nodes are in signal connection with a sensor through an analog differential transmission line;
s102, each acquisition node comprises an A/D conversion chip and a crystal oscillator which is subjected to PTP discipline, the working clock of the A/D conversion chip is derived from the crystal oscillator which is subjected to PTP synchronous discipline, a master clock node is set to be one acquisition node, the rest acquisition nodes are slave clock nodes, each acquisition node independently performs message exchange with the master clock node through a PTP protocol, all the acquisition nodes lock the master clock node, after the acquisition nodes lock the master clock node, the phase and frequency of the working clock of each acquisition node are synchronous with the master clock node, and after synchronization, each acquisition node continuously performs message interaction with the master clock node, and dynamic time synchronization is maintained;
s103, setting starting time for starting data acquisition by the acquisition nodes by the computing center, wherein the starting time is the sum of the current time and preset delay time, and distributing the starting time and the sampling frequency to each acquisition node through a TCP/IP protocol;
s104, after receiving the starting time and the sampling frequency configuration, each acquisition node continuously compares the starting time with the local time, when the starting time is equal to the local time, the A/D conversion chip is immediately controlled to start to acquire data by controlling the low level of the SYNC _ IN pin of the A/D conversion chip, the A/D conversion chip of each acquisition node simultaneously starts to acquire data, and the acquired data are uploaded to a computing center through a TCP/IP protocol.
In this embodiment, any one of the collection nodes is selected as a master clock node, and the remaining collection nodes are all slave clock nodes. MCLK of the A/D conversion chip of each acquisition node is derived from the crystal oscillator after PTP synchronization discipline, so that the working frequency and the clock phase of each acquisition node are equal for a long time, and the A/D conversion chip automatically controls the sampling interval by taking the clock as a source clock, so that the subsequent acquisition nodes can be guaranteed to sample simultaneously within the synchronization precision range.
The method for measuring the predetermined delay time is the same as the first embodiment, and is not cumbersome.
Example III,
As shown in fig. 1 and fig. 2, on the basis of the first embodiment, the invention provides a sensor data acquisition and transmission system based on PTP synchronization, which includes a plurality of sensors, a plurality of acquisition nodes, a plurality of switches, a computation center, a master clock node, and a slave clock node.
The computing center is respectively connected with an exchanger through a gigabit Ethernet transmission line in a signal mode, the exchanger is connected with the exchanger in series through the gigabit Ethernet transmission line, the exchanger is connected with a plurality of acquisition nodes through the gigabit Ethernet transmission line in a signal mode, and the acquisition nodes are connected with the sensor in a signal mode through analog differential transmission lines. In the present embodiment, j switches, j × m acquisition nodes, and j × m × n sensors are provided.
And the acquisition node is used for conditioning, analog-to-digital conversion and packaging transmission processing on the n-channel sensor signals. And the master clock node is used for giving time to each acquisition node, the master clock node is a calculation center or one acquisition node, the rest acquisition nodes are slave clock nodes, if the master clock node is the calculation center, all the acquisition nodes are slave clock nodes, and if the master clock node is one acquisition node, the rest acquisition nodes are slave clock nodes. Each collection node independently exchanges messages with the master clock node through a PTP (precision time protocol) protocol, each collection node communicates with the computing center through a TCP/IP (transmission control protocol/Internet protocol) protocol, as shown in figure 4, after a period of time, all the collection nodes lock the master clock node, the collection nodes are basically synchronous with the master clock node in second pulse, and after each collection node locks the master clock node, clocks among the collection nodes are indirectly synchronous, namely, the phases and the frequencies are synchronous. After the acquisition node locks the master clock node, the acquisition node still continuously performs message interaction with the master clock node, and dynamic time synchronization is maintained.
And the computing center controls the acquisition control and the acquisition data collection and processing of each acquisition node. The computing center monitors the state of each acquisition node, and can send an instruction to start the acquisition node to acquire data only after each acquisition node locks the master clock node. The starting instruction is completed by using a starting time, the starting time is the sum of the current time and the preset delay time, the starting time of all the acquisition nodes is the same, and the phase and the frequency of the working clocks of the sampling nodes are also the same. The computing center issues the configuration of the starting time and the sampling frequency to each acquisition node through a reliable transmission protocol, such as a TCP/IP protocol. After receiving the starting time and the sampling frequency configuration, each acquisition node continuously compares the starting time with the local time, and when the starting time is equal to the local time, the acquisition nodes start to acquire data at the same time. The acquisition nodes comprise an A/D conversion chip and a crystal oscillator which is acclimated synchronously by PTP, as shown IN fig. 4 and 5, the A/D conversion chip is controlled to start acquiring data by controlling the low level of a SYNC _ IN pin of the A/D conversion chip, and meanwhile, MCLK of the A/D conversion chip comes from the crystal oscillator which is acclimated synchronously by PTP, so that the working frequency and the clock phase of each acquisition node are equal for a long time, the A/D conversion chip automatically controls the sampling interval by taking the clock as a source clock, and therefore, the follow-up acquisition nodes can be guaranteed to sample simultaneously IN the synchronous precision range. Each acquisition node uploads acquired data to the computing center through a TCP/IP protocol, if sampling is required to be stopped, the computing center sends an acquisition stopping instruction to the acquisition nodes, and the stopping instruction is completed by using a stopping time. When stopping, each acquisition node is configured with the same stopping time.
And the switch is responsible for storing and forwarding the data of the collection nodes. The switch comprises a plurality of tera optical interfaces and gigabit electrical interfaces, and is also a transparent clock node in PTP synchronization, and the acquisition node is a boundary clock node in PTP synchronization and is also a powered device PD in Poe power supply technology. In the embodiment, the switch only directly forwards the Sync message, the Follow _ Up message and the Announce message, terminates other PTP protocol messages and participates in calculating the delay of each section of link on the whole link.
The working principle of the invention is as follows: each acquisition node independently exchanges messages with the main clock node through a PTP (precision time protocol), after a period of time, all the acquisition nodes lock the main clock node, after the acquisition nodes lock the main clock node, the phase and the frequency of the working clock of each acquisition node are synchronous with the main clock node, and after the synchronization, each acquisition node continuously exchanges messages with the main clock node, so that dynamic time synchronization is maintained. After each acquisition node locks the master clock node, the computing center sends an instruction to start the acquisition nodes to acquire data. The starting instruction is completed by using a starting time, the starting time is the sum of the current time and the preset delay time, the starting time of all the acquisition nodes is the same, and the phase and the frequency of the working clocks of the acquisition nodes are also the same. And the computing center issues the starting time and the sampling frequency configuration to each acquisition node through a TCP/IP protocol. After receiving the starting time and the sampling frequency configuration, each acquisition node continuously compares the starting time with the local time, when the starting time is equal to the local time, the A/D conversion chip is immediately controlled to start acquiring data by controlling the low level of the SYNC _ IN pin of the A/D conversion chip, the A/D conversion chip of each acquisition node simultaneously starts acquiring data, and meanwhile, the MCLK of the A/D conversion chip is derived from the crystal oscillator which is subjected to PTP synchronization domestication, so that the working frequency and the clock phase of each acquisition node are equal for a long time, and the A/D conversion chip automatically controls the sampling interval by taking the clock as a source clock, so that the subsequent acquisition nodes can be ensured to sample simultaneously IN a synchronization precision range. The A/D conversion chip collects data and sends the data to the collection nodes, each collection node conditions, converts analog to digital and packages and transmits the sensor signals under the collection nodes, the packaged data are sent to the switchboard through a TCP/IP protocol, and the switchboard forwards the data to the computing center for signal processing. If the system scale needs to be enlarged, and more data of the sensors are collected, the number of the switches and the collection nodes is increased.
Example four,
On the basis of the first embodiment or the second embodiment, in this embodiment, the switch supplies power by using a 36V-72V wide-range isolation power supply, and each acquisition node supplies power by using a network power supply PoE technology, which adopts a standard of 802.3af and supports 12.95W power output, and the PoE technology can automatically realize functions such as load detection, power classification, surge control, and the like. The isolation power supply is electrically connected with the switches through power lines respectively, a network power supply PoE technology is adopted on gigabit Ethernet transmission lines and ten-gigabit Ethernet transmission lines, the most valuable point of the network power supply PoE technology is that PoE adopts Ethernet cables for power transmission, a special power line is not needed for supplying power to the collection nodes, the service data, the synchronous messages and the power supply of the collection nodes are transmitted through one Ethernet transmission line, the number of power supply lines can be reduced, and the reliability of the system is improved. If one acquisition node is connected with a single sensor during implementation, the whole system has no analog cable except a main power supply line, and full digitalization and networking are really realized.
In this embodiment, the switch serves as both a transparent clock node in PTP synchronization and a power supply device Pse for supplying power to the collection node, where the collection node is a boundary clock node in PTP synchronization and is also a power receiving device PD in Poe power supply technology.
Example V,
On the basis of the third embodiment, the present embodiment configures a state register inside a switch chip to implement dual backup of a backbone network.
For a system in which a backbone network, such as a linear cascade switched ethernet, is in a serial connection mode, a failure of a certain serial node or link will cause data loss before the failed node, and the system risk is high. As shown in fig. 7 and 8, the backbone network is divided into a working link and a backup link, and in an initial state, the HOST and the N switches 10GbSW are connected in series to form the working link, and when the working link works, the switching port P1 and the port P2 are opened, and the port P3 and the port P4 are closed. And once a certain node on the working link is abnormal, automatically switching to the backup link corresponding to the node to work in a hot mode. As shown in fig. 7, in the default state, the switches on the working link all use the switch port P1 and the port P2, and when a switch fails, the switch automatically switches to the backup links of the switch port P3 and the port P4, thereby ensuring normal operation.
Example six,
On the basis of any one of the first embodiment to the fourth embodiment, the present embodiment is applied to the application scenario of vector hydrophone linear array military sonar. A single vector hydrophone includes three acceleration channels and one acoustic pressure channel, for a total of 4 channels. Therefore, a single acquisition node can be arranged to condition, analog-to-digital convert and package the single 4-channel vector hydrophone signal. If the vector towed array needs 320 vector hydrophones in total, the system can be configured in such a way that backbone network 40-stage switches are connected in series, each switch is connected with 8 acquisition nodes in a hanging mode, and each acquisition node acquires 4-channel data. Namely, in the system structure diagram, j is 40, m is 8 and n is 4. The link throughput is determined according to the sampling frequency and the total data volume of the acquisition node.
Under the application scenarios of large data volume transmission and ultra-far distributed sensor data transmission, a backbone network can be configured into a gigabit Ethernet switch and a gigabit transmission link, and the acquisition nodes can be connected with the switch by using the gigabit Ethernet. Therefore, the transmission delay can be reduced, and the PTP synchronization precision is improved while the real-time transmission of data is met; secondly, the requirement of mass data acquisition and transmission can be adapted.
Under the application scenes of low power consumption requirement and medium data transmission, a backbone network can be configured into a gigabit Ethernet switch and a gigabit transmission link, and a hundred-gigabit Ethernet connection can be adopted between the acquisition nodes and the switch.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (9)
1. The utility model provides a sensor data acquisition transmission system based on PTP is synchronous, its includes a plurality of sensor, a plurality of collection node, a plurality of switch and calculation center, its characterized in that: the system also comprises a master clock node and a slave clock node;
the acquisition node comprises an A/D conversion chip and a crystal oscillator subjected to PTP synchronous taming;
the working clock of the A/D conversion chip is derived from the crystal oscillator which is synchronously disciplined by PTP;
the master clock node is a computing center or an acquisition node, and the rest acquisition nodes are slave clock nodes;
the acquisition nodes exchange messages with the master clock node through a PTP (precision time protocol), each acquisition node locks the master clock node, and each acquisition node uploads service data to the computing center through a TCP/IP (transmission control protocol/Internet protocol);
the computing center is in signal connection with an exchanger through a gigabit Ethernet transmission line, the exchanger is connected with the exchanger in series through the gigabit Ethernet transmission line, the exchanger is in signal connection with a plurality of acquisition nodes through the gigabit Ethernet transmission line, and a plurality of sensors are in signal connection with one acquisition node through an analog differential transmission line;
the Ethernet backup transmission line also comprises a gigabit Ethernet backup transmission line;
and ten-gigabit Ethernet backup transmission lines are adopted between the computing center and the switch and between the switches.
2. The sensor data acquisition and transmission system based on PTP synchronization of claim 1, wherein: the calculation center sets the starting time and the stopping time of data acquisition and adjusts the sampling frequency, the working frequency and the gain;
the starting time is the sum of the current time and the preset delay time;
and the computing center issues the configuration of the starting time and the sampling frequency to each acquisition node through a reliable transmission protocol.
3. The sensor data acquisition and transmission system based on PTP synchronization of claim 1, wherein: the device also comprises an isolated power supply with a wide range of 36V-72V;
the switch adopts a 36V-72V wide-range isolation power supply to supply power, and adopts a network power supply Poe technology to supply power to the acquisition nodes.
4. The sensor data acquisition and transmission system based on PTP synchronization of claim 3, wherein: the switch comprises a plurality of tera optical interfaces and a gigabit electrical interface;
the switch is a transparent clock node in PTP synchronization and is a power supply device Pse in Poe technology for supplying power to the acquisition node;
the acquisition node is a boundary clock node in PTP synchronization and is a powered device PD in Poe power supply technology.
5. A sensor data acquisition and transmission method based on PTP synchronization comprises the following steps:
s101, building a system framework that a computing center is in signal connection with an exchanger through a gigabit Ethernet transmission line, the exchanger is connected with the exchanger in series through the gigabit Ethernet transmission line, the exchanger is in signal connection with a plurality of acquisition nodes through the gigabit Ethernet transmission line, and the acquisition nodes are in signal connection with a sensor through an analog differential transmission line;
s102, each acquisition node comprises an A/D conversion chip and a crystal oscillator which is subjected to PTP discipline, the working clock of the A/D conversion chip is derived from the crystal oscillator which is subjected to PTP synchronous discipline, a main clock node is set as a calculation center or one acquisition node, the rest acquisition nodes are slave clock nodes, each acquisition node independently exchanges messages with the main clock node through a PTP protocol, all the acquisition nodes lock the main clock node, after the acquisition nodes lock the main clock node, the phase and the frequency of the working clock of each acquisition node are synchronous with the main clock node, and after synchronization, each acquisition node continuously performs message interaction with the main clock node, and dynamic time synchronization is maintained;
s103, setting starting time for starting data acquisition by the acquisition nodes, adjusting sampling frequency by the computing center, and sending the starting time and the sampling frequency configuration to each acquisition node through a TCP/IP protocol;
s104, after receiving the starting time and the sampling frequency configuration, each acquisition node continuously compares the starting time with the local time, when the starting time is equal to the local time, the A/D conversion chip is immediately controlled to start to acquire data by controlling the low level of the SYNC _ IN pin of the A/D conversion chip, the A/D conversion chip of each acquisition node simultaneously starts to acquire data, and the acquired data are uploaded to a computing center through a TCP/IP protocol.
6. The sensor data acquisition and transmission method based on PTP synchronization of claim 5, wherein: and in the S101, the switch supplies power by adopting a 36V-72V wide-range isolation power supply and supplies power to the acquisition node by adopting a network power supply Poe technology.
7. The sensor data acquisition and transmission method based on PTP synchronization of claim 6, wherein: the switch comprises a plurality of tera optical interfaces and a gigabit electrical interface;
the switch is a transparent clock node in PTP synchronization and is a power supply device Pse in Poe technology for supplying power to the acquisition node, and the acquisition node is a boundary clock node in PTP synchronization and is a power receiving device PD in Poe power supply technology.
8. The sensor data acquisition and transmission method based on PTP synchronization of claim 5, wherein: in the S101, ten-gigabit Ethernet backup transmission lines are adopted between the computing center and the switch and between the switch and the switch to form backup links;
the backup link is completed by configuring the internal status register of the switch chip.
9. The sensor data acquisition and transmission method based on PTP synchronization of claim 5, wherein: the starting time in S103 is the sum of the current time and the preset delay time.
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| CN109831267B (en) * | 2019-02-26 | 2020-10-27 | 武汉海晟科讯科技有限公司 | Cascade synchronous data acquisition and transmission system based on PTP (precision time protocol) |
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| CN111447030B (en) | 2020-03-31 | 2021-02-19 | 中国科学院地质与地球物理研究所 | Network time service precision control method and system of earthquake collector and terminal equipment |
| CN112858624A (en) * | 2021-01-19 | 2021-05-28 | 浙江大学 | Multi-node sensor array structure and data acquisition and disaster early warning device thereof |
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