FR2755557A1 - COMMUNICATION DEVICE AND METHOD FOR PRECISE DATE OF EVENTS - Google Patents

Abstract

The communication device comprises a central (1) and stations connected by a network (4). The central unit (1) comprises first means (10, 11, 12) for correcting the effects of the processing time of the transmission of a synchronization frame. A station (6d) comprises second correction means (15, 16) for correcting the effects of the processing time of the reception of said synchronization frame, and management means (17) of a local time. Events dated in local time by the station are then corrected and dated in absolute time in the control unit.

Description

AT

  COMMUNICATION DEVICE AND METHOD FOR PROVIDING

PRECISE DATE OF EVENTS

  The invention relates to a communication device comprising: - a communication central comprising first frame communication means, - at least one communication network connected to the first communication means of the central, - at least one station comprising second means for communicating frames connected to the communication network, - a clock connected to the first communication means of the central unit providing a time information signal, and - information processing means connected to the central unit, Known communication devices include a central and stations connected to the central by a communication network. Communication stations send frames to the central unit of information concerning, for example, the status of electrical devices

associated with said stations.

  The central unit processes the information frames in the order of arrival. However, for certain applications, it is necessary to date the information received by the frames. In that case,

  a clock is connected to the central unit to provide the date and time.

  The central unit then combines information representative of particular events received by the frames and time information provided by the clock. The two types of associated information are processed and then, for example, recorded in devices for

memorization or display.

  In this embodiment, the event information is associated with time information when it is received by the central. However, this type of dating is not very precise. Indeed, quite a long time may elapse between the moment when an event occurs at a station and the moment when the information is

dated in the central.

2 2755557

  The object of the invention is a communication device and method allowing a

precise dating of events.

  According to the invention, the device comprises: - means for determining delays caused by the processing of communication frames comprising time information, connected to communication means, and - correction means, connected to the determination means and to means of communication, to correct time information carried by frames of

communication.

  In a preferred embodiment of the invention, the central unit comprises: - first means for determining delays, caused by the first communication means of the central unit, connected to the clock and to means for transmitting the first means of communication from the central unit, and - from the first correction means connected to the first determination means, to means for receiving the first communication means, and to the means for

information processing.

  According to a development of the preferred embodiment, the transmission means of the first communication means of the central station provide, to the first means of

  determination, a signal representative of the transmission of a frame.

  The first correction means provide the information processing means with dated information as a function of hourly information values supplied by frames received by the reception means of the first communication means increased by

  first delay values provided by the first determination means.

  Preferably, the central unit includes storage means connected to the first

  means of determining delays.

3 2755557

  In a particular embodiment, at least one station comprises: second means for determining delays, caused by the second communication means of the station, connected to means for receiving the second communication means of the station, and - second correction means connected to the second determination means, to the second means for receiving the second communication means of the station, and to

  means of managing a local time of the station.

  According to a development of the particular embodiment, the means for receiving the second communication means of the station provide the second means with

  determination, a signal representative of reception of a frame.

  The second correction means correct hourly information values, of frames supplied by the reception means of the second communication means, as a function of second delay values supplied by the second determining means, hourly information values being increased values representative of said second values

delay.

  The station comprises processing means supplying a frame comprising event information associated with timetable information, connected to the local time management means, to event detection means and to means

  transmission of the second means of communication.

  A first method according to the invention comprises: - a step of requesting transmission of a first frame comprising time information, - a step of processing the transmission of the first frame, - a step of determining the duration of processing of the transmission of the first frame, - a step of memorizing the value of the processing time of the transmission of the first frame, - a step of receiving a second frame comprising a second time information, and - a step of correcting the second time information as a function of the value of the

  processing time of the transmission of the first frame.

4 2755557

  A second method according to the invention comprises: - a step of detecting reception of a first frame comprising time information, - a step of processing the reception of the first frame, - a step of determining the processing time of the reception of the first frame, - a step of correcting the value of the hourly information of the first frame, - a step of loading the corrected value, of the hourly information, in a local time manager, - an event detection step, a step for constituting a second frame comprising information on the event and local time information, and

  a step of transmitting said second frame.

  Other advantages and characteristics will emerge more clearly from the description which follows.

  to follow, of particular embodiments of the invention, given by way of nonlimiting examples, and represented in the appended drawings in which:

  - Figure 1 shows a block diagram of a communication device of known type.

  FIG. 2 represents a block diagram of a communication device according to a mode of

realization of the invention.

  - Figure 3 shows a flowchart for sending a frame by a central unit of a device

  according to one embodiment of the invention.

  - Figure 4 shows a flowchart of reception of a frame by a station of

  device according to an embodiment of the invention.

  - Figures 5 and 6 show two flowcharts for processing frames respectively

  sent by a station and received by a central.

  - Figure 7 shows a block diagram of a communication device according to a second

  embodiment of the invention.

2755557

  The communication device of FIG. 1 comprises a central unit 1, a clock 2 connected to the central unit, an information processing device 3, a first and a second communication network 4 and 5 respectively, stations 6a, 6b and 6c connected to the first network 4 and stations 7a, 7b and 7c connected to the second network 5. The central unit 1 communicates with the stations and receives information representative of events detected by said stations. The information is dated in the central unit then supplied to the processing device 3. The device 3 allows, in particular, to

  memorize or record dated information.

  Clock 2 provides the center with time information to date the events received

  by the central. This time information includes day and time information.

  They will be considered as the absolute time of the communication device.

  When an event is detected by a station, said station sends a frame comprising information representative of the event. The frame is received by the central unit which processes the frames and dates the information representative of events. Then the information

  dated are transmitted to the processing device 3.

  This method of dating events is sufficient as long as the accuracy of the dating is not critical. Indeed, a significant delay may elapse between the appearance of an event

  and the time of the dating of this event.

  To overcome this drawback, in one embodiment of the invention, stations, the events of which must be dated with precision, include a device for managing a local time. This local time management device makes it possible to date an event as soon as it is detected by the station. Thus, the station produces a frame comprising information representative of the detected event and time information provided by the local time management device. The frame, sent by the station, is received and processed by the central. Then the information dated by the station is transferred to the processing device 3.

6 2755557

  The local time management device in the station makes it possible to avoid the dating problems caused by the time of transmission of the frame in the station and by the time

  frame reception and processing in the central.

  To ensure consistent time information across the communication device, the central office clock and local time management devices must be synchronized. This synchronization is done by the transmission of frames containing synchronization time information. These frames are sent by the central to

  stations incorporating local time management devices.

  The processing of frames in the central unit delays the sending of said frame to the stations. Consequently, the value of the time information of the frame is different from the absolute time

  of the clock when the frame is sent.

  The problem of delay due to treatment is also present in the stations. Indeed, a time information frame received by a station is processed before being used for example to synchronize the local time management device. The processing carried out in the station induces an additional delay which also affects the time information

conveyed by the frame.

  The processing times for sending and receiving synchronization time information frames can also affect the accuracy of dating events if this

dating must be very precise.

  Figure 2 shows a diagram of a communication device, according to a mode of

  realization of the invention, allowing very precise dating of events.

  In this embodiment, the central unit 1 comprises a first circuit 8 for processing the transmission of frames and a first circuit 9 for processing the reception of frames connected to a communication network 4, a first calculation module 10 connected to the circuit 8 and to the clock 2, a storage circuit 11 connected to the calculation module 10, and a first correction module 12 connected to the calculation module 10 and to the reception processing circuit 9.

7 2755557

  A station 6d, also shown in FIG. 2, comprises a second circuit 13 for processing frame reception and a second circuit 14 for processing frame transmission connected to the network 4, a second calculation module 15 connected to the second circuit 13 , a second correction module 16 connected to the circuit 13 and to the calculation module 15, a local time management device 17 connected to the second correction module 16, and an event processing circuit 18 connected to the management device 17 and to the second transmission processing circuit 14. The event processing circuit 18 of the station 6d

  is connected to an event detector 19d associated with the station 6d.

  In the diagram in Figure 2, a second station 6e is connected to network 4 and a second

  detector 19th is associated with the second station 6th.

  In the embodiment of FIG. 2, during a phase of synchronization of the local time of the stations, the clock 2 sends, to the transmission processing circuit 8 and to the calculation module 10, a signal 20 d time transmission including absolute time information CK1. The processing circuit 8 processes the time information CK1 and sends a frame comprising this information. When the frame is sent, the circuit 8 provides the module 10 with a signal 21 representative of the end of processing of the transmission of the frame comprising time information. The module 10 calculates a delay value EC1 representative of the

  delay between the instants of appearance of signals 20 and 21.

  A signal 22 representative of the delay value EC 1 is supplied to the storage circuit

11 to save the EC1 value.

  The frame containing the time information sent by the central unit is reviewed by stations 6d and 6e. In station 6d, the second circuit 13 for processing the frame reception provides the calculation module 15 with a signal 23 representative of the frame reception and a signal 24 comprising the time information CK1 after processing of the frame reception.

8 2755557

  The calculation module 15 calculates a delay value EC2 representative of the delay between the instants of appearance of the signals 23 and 24. A signal 25 representative of the delay value

  EC2 and signal 24 are supplied to the correction module 16.

  The correction module 16 corrects the value of the time information CK1 supplied by the signal 24 to provide a signal 26 representative of a specific local time CKL1. The correction consists in particular in adding the value EC2, representative of the processing delay on reception of the frame, to the value of the hourly information received CK1. Thus, the value of local time is, at the time of correction, substantially equal to the sum

  values representative of the absolute time CK1 and of the duration of the delay EC2.

  The signal 26 representative of the instantaneous value of the local time is supplied to the device 17 for managing the local time. The value of the local time is then synchronized as a function of the value of the absolute time sent by the central unit and corrected by the module 16. When the synchronization is carried out, the device 17 includes a local clock which provides a local time CKL1 synchronized with the absolute time CK1 supplied by the central unit. This local time can however be offset from the absolute time, by a

  value equal to the value of the EC 1 central unit processing time.

  When the event detector 19d detects an EVST1 event, it supplies a signal 27 representative of said event to the processing circuit 18. The management device 17 supplies to the circuit 18 a signal representative of the local time at which the event occurs. Then, the processing circuit 18 provides a frame signal comprising information representative of the event and information representative of the local time CKL1 at which the event occurred. The transmission of the frame is then processed by the second

  circuit 14 for processing the transmission of frames which sends the frame on the network 4.

  The frame sent by circuit 14 of the station is received by the central. The first frame reception processing circuit 9 supplies the first connection module 12 with a signal 30 representative of the event information and of the time information in local time. The correction module 12 corrects the value of the local time CKL1 of the frame as a function of the value EC1 of delay in processing the transmission from the central unit. This delay value is supplied to module 12 by calculation module 10 or by the

storage 11.

9 2755557

  The correction of the local time of the frame consists, in particular, in adding the value of the

  delay to the value representative of local time.

  Information representative of the event and the corrected time at which

  the event is detected are supplied to the information processing device 3.

  With the correction of the time information in the central unit by the module 12 and in the stations by the module 15, the events coming from the stations with correction modules 15 are dated in absolute time. The dating of these events is therefore very precise and the chronology of the appearance of the events can be effectively treated by the

device 3.

  Since the dating can be very precise, of the order of a millisecond, the hourly information can also be expressed to the nearest millisecond. For example, information

  schedule can have the following format: day, hour, minute, second, millisecond.

  FIG. 3 shows a flowchart for sending a frame by a central unit 1. In this method according to an embodiment of the invention, during a first step 31, at a time tl, a request for transmission of synchronization frame with a CK1 absolute time value is required. Then, during a step 32, the processing of the transmission of the frame is carried out. At an instant t2 (step 33), the frame is sent and a signal for the end of transmission processing is supplied. Then, in a step 34, a calculation of a delay EC1 is carried out. The value of the delay EC1 is representative of the duration between the instants t2 and tl

  (EC1 = t2 - tl). In a step 35, the value of the delay EC1 is stored.

  A flowchart for receiving a frame by a station is shown in FIG. 4. The reception of a frame begins with a step 36 at an instant t3. Then, the processing of the reception of the frame comprising time information CK1 is carried out during a step 37. At an instant t4 (step 38), the end of processing of the frame is detected. Then, in a step 39, a calculation of a delay EC2 is carried out. The value of the delay EC2 is representative of the duration between the instants t4 and t3 (EC2 = t4 t3). In a step 40, a local time CKL1 is calculated, it corresponds substantially to the sum of the time information CK1

2755557

  and EC2 delay. Then, in a step 41, the calculated value of the local time is loaded for

  synchronize the local time of the station with the absolute time of the central.

  This method of receiving the station makes it possible to avoid the effects caused by the delay produced by the processing of the frame reception. The correction is done directly in the

single phase station.

  A flow diagram for sending a frame by a station is shown in FIG. 5. In a step 42, an EVST event is detected at a local time CKLST. Then, in a step 43, a processing is carried out to produce a frame comprising information relating to the event and time information representative of the local time at

  which the event occurred. Then the frame is transmitted, during a step 44.

  Frame reception by the central unit is represented by a flowchart in FIG. 6. In a step 45, the central unit processes the reception of a frame comprising event information EVST and time information CKLST of local time. Then in a step 46, the central unit corrects the value of the hourly information of local time to date the event in absolute time. Thus, the event is dated as if the time of occurrence of the event was provided directly by the clock associated with the central unit. The correction of the time information consists of providing absolute time information CKAEV representative of the sum of the local time of the CKLST event and the value of the processing delay EC1

  the transmission of the synchronization frame by the central unit (CKAEV = CKLST + EC1).

  Then, in a step 47, the central unit sends the information processing device a

  EVST event information dated in absolute time CKAEV.

  This method of receiving the central unit overcomes the effects of the delay produced by the transmission of a frame by the central. In this process the correction is done in two phases. A first phase consists in determining the delay in transmission and a second phase consists in correcting the time information of the frames received by the central unit

as a function of the delay in transmission.

  In the embodiments according to the invention described above, the accuracy of the dating of the events can be of the order of lms. This communication device is

  particularly well suited to installation surveillance communication networks.

  For example, when stations are associated with circuit breakers and o event detectors are linked to trip devices or auxiliary contacts. In this case, precise dating of events makes it easy to identify the place and the time

  appearance of electrical faults.

  The control unit 1 can communicate with the stations through several different networks. A diagram of a communication network comprising a central communicating through

  two networks are shown in Figure 7.

  In this embodiment, the central unit 1 comprises two first processing circuits 8a and 8b for the transmission of frames connected respectively to networks 4 and 5, and two first processing circuits 9a and 9b for receiving the frame also connected to the networks 4 and 5 respectively. A station 6f is connected to network 4 and a station 7d is

connected to the network 5.

  During a synchronization phase, the clock 2 sends to circuits 8a, 8b and to module 10

  CK1 time information in absolute time.

  Each circuit 8a, 8b processes the transmission of a frame comprising time information CK1. Then, the circuits 8a and 8b supply the module 10 with signals respectively 21a

  and 21b when their respective frame is sent.

  Module 10 calculates delays EC1 and EC2 due to the respective processing of the two

  circuits 8a and 8b, then stores them in the storage circuit 11.

  When receiving frames from the network 4, the circuit 9a processes the reception and sends a signal 30a comprising event information and local time information. The correction module 12 corrects the time of the event in absolute time as a function of the delay value EC1 determined during the synchronization phase. Then,

  the module 12 provides the device 3 with the information of the event dated in absolute time.

  In the same way, the circuit 9b processes the reception of frames coming from the network 5 and provides the module 12 with a signal 30b comprising event and local time information. The

12 2755557

  module 12 corrects the time of the event according to the EC2 delay previously determined

  then provides the device 3 with the information of the event dated in absolute time.

  In the above embodiments, the clock 2 is shown next to the central, but it is obvious that this clock can be integrated into the central or remote far from

the power plant.

  In the communication devices according to embodiments of the invention, it is not necessary that all the events, detected by all the stations, be dated very precisely. Devices can have very precisely dated event stations and stations on the same or different networks.

  less precisely dated events.

  The sending of synchronization frames can be initiated manually by a user or preferably automatically by the central unit. The frequency of these

  frames can be, for example, predetermined and regular.

  The circuits and modules described above in the communication device can be separated or preferably integrated into the same microcontroller or microprocessor. Similarly, functions of said circuits and modules can be realized in a form

  programmed operating with a microprocessor.

13 2755557

Claims (11)

  1. Communication device comprising: - a communication center (1) comprising first means (8, 9, 8a, 9a, 8b, 9b) for frame communication, - at least one connected communication network (4, 5) to the first communication means of the central unit, - at least one station (6a-6f, 7a-7d) comprising second means (13, 14) for communicating frames connected to the communication network, - a clock (2) connected to the first communication means of the central unit providing a time information signal (20), and - means (3) for processing information connected to the central unit, device characterized in that it comprises: - means (10, 15) for determining delays caused by the processing of communication frames comprising time information, connected to means (8, 8a, 8b, 13) of communication, and - correction means (12, 15) connected to the means of determination and means of communication, to correct time information carried by frames of communication.   2. Communication device according to claim 1 characterized in that the central unit (1) comprises: - first means (10) for determining delays caused by the first central station communication means, connected to the clock and to means (8, 8a, 8b) for transmitting the first communication means of the central unit, and - first correction means (12) connected to the first determination means (10), to means (9, 9a, 9b ) of receipt of the first means of   communication, and means (3) for processing information.   3. Communication device according to claim 2 characterized in that the means (8, 8a, 8b) for transmitting the first communication means of the central unit supply, to the first means (10) for determining, a signal (21, 21a , 21b)   representative of the transmission of a frame. 14 2755557   4. Communication device according to one of claims 2 or 3 characterized in that   that the first correction means (12) supply the information processing means (3) with dated information as a function of hourly information values supplied by frames received by the means (9, 9a, 9b) for receiving the first means of communication increased by first delay values provided by the first means (10) of determination.   5. Communication device according to any one of claims 2 to 4   characterized in that the central unit includes storage means (11) connected to the   first means (10) for determining delays.   6. Communication device according to any one of claims 1 to 5   characterized in that at least one station comprises: - second means (15) for determining delays, caused by the second communication means of the station, connected to means (13) for receiving the second communication means of the station , and - second correction means (16) connected to the second determination means (15), to the second means (13) for receiving the second communication means from the station, and to means (17) for managing a local station time. 7. Communication device according to claim 6 characterized in that the means (13) for receiving the second communication means of the station provide, to the second means (15) for determining, a signal (23) representative of reception of a frame.   8. Communication device according to one of claims 2 or 3 characterized in that   that the second correction means (16) correct hourly information values, of frames supplied by the reception means of the second communication means, as a function of second delay values supplied by the second determining means, of the values of time information being increased by values representative of said times second delay values. 2755557   9. Communication device according to any one of claims 6 to 8   characterized in that the station comprises processing means (18) supplying a frame comprising event information associated with timetable information, connected to the means (17) for managing a local time, to means (19d , 19e) for detecting events and for means (14) for transmitting second communication means. 10. A communication method characterized in that it comprises: - a step (31) of requesting transmission of a first frame comprising time information, - a step (32) of processing the transmission of the first frame , - a step (34) of determining the duration of processing of the transmission of the first frame, - a step (35) of memorizing the value of the processing duration of the transmission of the first frame, - a step (45) of receiving a second frame comprising a second time information, and - a step (46) of correcting the second time information as a function of the value of   the processing time for the transmission of the first frame.   11. A communication method characterized in that it comprises: - a step (36) of detecting reception of a first frame comprising time information, - a step (37, 38) of processing the reception of the first frame , - a step (39) of determining the processing time of the reception of the first frame, - a step (40) of correcting the value of the time information of the first frame, a loading step (41) of the corrected value, of the time information, in a local time manager, - a step of (42) event detection, - a step (43) of constitution of a second frame comprising information on the event and local time information, and   - A step (44) of transmitting said second frame.