EP0361298B1 - Collecting system of alarms from a group of stations - Google Patents

Abstract

A central station (SC) is connected in series with the stations by a looped connection comprising a message loop (BM), a clock-signal loop (BH) and a state-control loop (BCE). Each station comprises an interface (I) connected to the various loops of the connection. The message loop routes messages transmitted by the central station destined for at least one interface, the responses from the interfaces, and messages transmitted by the interfaces destined for the central station. The clock-signal loop routes a clock signal transmitted by the central station and the state-control loop routes a state-control signal transmitted by the central station, this signal having a first value for a drive mode of operation and a second value for a reserve mode of operation of the interfaces; the passing from the first to the second value enables the control of a reset to zero of the interfaces. The clock and state-control signals have the same circulation sense, the messages having an inverse circulation sense.

Description

The invention relates to the interrogation of different stations of a set of stations, in order to know their operating state.

By station is meant any electronic command or control device, automatic workstation, or computer, which are, for example, part of a production line, of a set of computers connected by a bus, of a central telecommunications in which the stations are electronic devices such as recorders, taxers, markers, translators, control bodies, connection units, connected to a connection network. The stations can therefore talk to each other, be independent or even be controlled by a central control unit.

A station transmits alert signals, each alert signal having a precise meaning such as parameter or value reaching a threshold, malfunction or failure of an organ of the station. In the following, we will designate by alarm any reported fault or failure. Knowledge of these alarms provides information on the operating status of the station.

The alarms are generally routed by cables to a central station where they are analyzed, which leads to a concentration of cabling depending on the number of stations and the number of alarms per station, with all the drawbacks which result from this, in particular the congestion wiring and its price.

The document GB-A-2 080 000 describes a system for collecting alarms from a set of n stations, comprising a central station for grouping alarms, each station comprising at least one interface for collecting alarms from said station, and a link connecting the central station and interfaces in series; said link carrying messages sent by each of the stations to destination of the central station. But the central station does not send any message to the stations.

The document IEE Proceedings-G / Electronic circuits and systems, vol. 135, n ° 1, part G, February 1988, p. 1-10 Stevenage, Herts, Al-Kalili & al. "Multiple single-chip microcomputer approach to fire detection and monitoring system" describes an alarm collection system comprising a loop link, and where each station is identified by an address.

The object of the invention is to collect the alarms from the stations of a set of stations which do not have the drawbacks of collecting each of the alarms by wiring.

• une boucle de commande d'état acheminant un signal de commande d'état délivré par la station centrale pour imposer un mode de fonctionnement, pilote ou réserve, à toutes les interfaces; ledit signal de commande d'état ayant une première valeur pour un mode de fonctionnement pilote et une deuxième valeur pour un mode de fonctionnement réserve;
• et une boucle de signal d'horloge, acheminant un signal d'horloge délivré par la station centrale à destination de toutes les interfaces.

The subject of the invention is a system for collecting alarms from stations of a set of n stations each identified by an address, and each comprising at least one interface for collecting alarms from said station; including a central alarm grouping station; and a loop link connecting the central station and the interfaces in series; an output of each interface being connected to an input of another interface; said loop link comprising a message loop carrying messages sent by the central station to at least one interface, and a response from each destination station, and carrying messages sent by the interfaces to the central station; characterized by the fact that said loop link also comprises:

• a status control loop carrying a status control signal delivered by the central station to impose an operating mode, pilot or reserve, on all the interfaces; said state control signal having a first value for a pilot operating mode and a second value for a reserve operating mode;
• and a clock signal loop, carrying a clock signal from the central station to all interfaces.

• la figure 1 est un schéma de principe d'un système de collecte des alarmes de l'invention,
• la figure 2 représente un mode de réalisation d'un système de l'invention,
• la figure 3 représente une interface de chaque station du système de l'invention,
• la figure 4 représente un autre mode de réalisation d'un système de l'invention,
• les figures 5 à 10 représentent des messages destinés à des stations du système de l'invention selon les figures 2 et 4, la figure 5 étant relative à un message de lecture des alarmes, la figure 6 étant relative à un message d'initialisation, la figure 7 étant relative à un message de télécommande, la figure 8 étant relative à un message d'essais, la figure 9 étant relative à un message octets non identifiés et la figure 10 étant relative à un message de positionnement de voyants d'alarmes.

The invention will be described with the aid of exemplary embodiments illustrated by the appended figures in which:

• FIG. 1 is a block diagram of an alarm collection system of the invention,
• FIG. 2 represents an embodiment of a system of the invention,
• FIG. 3 represents an interface of each station of the system of the invention,
• FIG. 4 represents another embodiment of a system of the invention,
• FIGS. 5 to 10 represent messages intended for stations of the system of the invention according to FIGS. 2 and 4, FIG. 5 being relating to a message for reading the alarms, FIG. 6 being relating to an initialization message, FIG. 7 relating to a remote control message, FIG. 8 relating to a test message, FIG. 9 relating to an unidentified byte message and FIG. 10 relating to a message for positioning of warning lights .

FIG. 1 schematically represents the system of the invention. A central station SC for collecting alarms is connected in series to a set of n stations S1 to Sn by a message loop BM which is an asynchronous serial link. The stations S1 to Sn are each identified by an address which is a number, the order of succession of the stations is not necessarily that of the addresses, the first station S1 of the set of stations being connected to a transmission terminal Tx of the central station, and the last station Sn of said set of stations being connected to a reception terminal Rx of the central station. Each station has an interface I connected at input and output to the message loop BM; each interface receives from the central station, a clock signal H necessary for its operation, and groups the alarms of the corresponding station which reach it by an alarm link AL; following a message sent by the central station SC, the alarms are sent on the message loop BM.

Figure 2 is an embodiment of the system of Figure 1. The central station SC and the stations S1 to Sn are connected in series, as in Figure 1, by the message loop BM. They are also connected in series, by a clock signal loop BH and a state control loop BCE; the last station Sn of the set of stations is connected, by these two loops, to a transmission terminal HE and to a transmission terminal CE of the central station, these terminals transmitting a clock signal and a status control signal , respectively ; the first station S1 of the set of stations is connected, by these two loops, to a reception terminal HR of the clock signal and to a reception terminal RE of the state control signal, of the central station SC.

In the stations, the BH and BCE loops are connected to the I interfaces.

The BM, BH and BCE loops are combined to form a cord between two stations, and between the central station and a station. In the event of a cord cut, the stations located downstream of the cut always receive, taking the direction of flow of messages on the BM loop as a reference, the clock signal and can transmit as will be specified below; similarly these stations can receive the status control signal by the BCE loop.

In FIGS. 1 and 2 each interface is connected to the station by a remote control link LT by which it issues the remote control orders sent by the central station over the message loop BM.

FIG. 3 represents an interface I of a station Si, all the interfaces of the stations being identical. In this figure, mP represents a microcontroller with its memories, whether these are internal or external to the microcontroller, 1 is a parallel / serial register, 2 is an AND gate, 3 is a station address device, this address being a number given for example by wiring, I / O are transmitters / receivers.

To the right of the figure, the loops BM, BH and BCE are connected to the station S (i + 1); on the left of the figure they are connected to the station S (i - 1). The microcontroller mP has a reception input RD connected to the message loop BM by an E / R transmitter / receiver, a transmission output TD connected to the message loop BM by a transmitter / receiver, a clock input CLK connected to the signal loop BH clock signal by a transmitter / receiver whose output is connected by another transmitter / receiver to the clock signal loop connected to the station S (i - 1), an ECE status control input connected to the BCE status control signal loop by a transmitter / receiver whose output is connected by another transmitter / receiver to the BCE status control signal loop connected to the station S (i - 1). It can be seen that the microcontroller mP is in a way in series with the message loop BM while it can be considered as a derivation with respect to the clock signal BH and state control signal BCE loops. The mP microcontroller also has a remote control output connected to the station by an LT remote control link.

The parallel / serial register 1 has a parallel input connected at the output of the AND gate 2, one input of which is connected to the alarm link AL which carries the alarm signals from the station, and another input is connected by a link write LW to a write output W of the microcontroller mP which delivers by said write link an order to write the alarms in register 1; a serial output of register 1 is connected to a data input D of the microcontroller. A clock input of register 1 is connected to a clock output h of the microcontroller mP which delivers on this output a clock signal H for reading of register 1; this signal clock is applied only after the write signal, and is deleted when the reading of register 1 is finished. The alarm link AL is for example a link with sixteen lines, one line per alarm; register 1 is then a sixteen-bit register; the clock signal H must therefore, in this case, be applied for a time at least equal to sixteen periods of the clock signal, to shift the bits of the register towards the output; after reading, all the bits of the register are at zero and the register is ready to receive alarms on the order of the microcontroller.

The alarm link AL is also connected at the output of an alarm output circuit 5. It is then connected to a circuit for controlling the lighting of indicator lights; this control circuit, not shown, is located in the station and controls the lighting of grouped indicators in a station supervision room. The alarm output circuit 5 is a register connected at the output of an AND gate 6 connected at the input to the data input D, to the write output W and to a CV control output of the microcontroller which delivers by this output of CV command of the LED positioning commands.

When the interface I is responsible for collecting alarms register 5 is used for the online test of the alarm link AL.

When the interface I is used to position the warning lights, register 5 is used to give the state of these warning lights, and in this case the AL alarm link is an output for the interface I and will attack the indicator light control circuit; in this case the interface I does not collect alarms.

The station address device 3 contains the address of the station, which is a number given for example by wiring; this device is connected at the output to a station address input of the mP microcontroller.

Each interface includes a converter 4 which delivers a DC voltage of + 5V. For operational safety reasons the converter 4 is connected at the input to two independent power supplies -48V (1) and -48V (2) of -48 volts each; these two power supplies are coupled by diode to the input of the converter.

FIG. 4 represents another embodiment of the system of the invention.

In this figure 4, each station S1 to Sn has two identical interfaces I1 and I2. The interfaces I1 are linked to the central station SC by a link L1 comprising a message loop BM, a clock signal loop BH and a state control loop BCE; the interfaces I2 are connected to the central station SC by a link L2 comprising a message loop BM, a clock signal loop BH and a state control loop BCE. The device operates as a pilot / reserve, switching over to an L1 or L2 link either by a periodic task or when an anomaly is detected on the pilot chain.

The status control signal delivered by the central station SC on the status control loop BCE of the links L1 and L2 imposes on the interfaces the type of operation, pilot or reserve, depending on whether this signal has the value 1 or the value 0. The pilot / reserve transition, that is to say the passage from the value 1 to the value 0 of the status control signal, requires a reset to zero of the interfaces which are therefore initialized.

In the interfaces, a control signal of value 1 validates the remote control and positioning control outputs of the microcontroller LEDs, and a control signal of value 0 blocks these outputs.

In the device of FIG. 2, a control signal imposes on all interfaces a pilot or reserve operation, the reserve operation prohibiting any remote control and any control of indicator lights in the stations.

In the device of FIG. 4, each station having two interfaces I1 and I2, when the interfaces I1 are pilot the interfaces I2 are in reserve, and vice versa, so that it is always possible for the central station SC to control remote controls and indicator positions in the stations, even in the event of an L1 or L2 link cut, or in the event of an I1 or I2 interface failure.

Information exchange between stations and the station central SC are made, except anomalies, on the initiative of said central station which sends messages to the stations.

• lecture des alarmes : ce message permet à la station centrale de connaître les alarmes collectées par les interfaces I des stations ;
• exécution de télécommandes : ce message commande une action dans chaque station destinataire ;
• positionnement de voyants : ce message commande dans chaque station destinataire l'allumage de voyants d'alarme ;
• octets non identifiés : ce message est émis spontanément par une station qui n'a rien reçu depuis un certain temps, ou qui a reçu successivement deux octets non identifiés ;
• essai : ce message permet à la station centrale de s'assurer du bon fonctionnement des interfaces I.
• initialisation : ce message permet à la station centrale SC de connaître la configuration de la boucle de message, c'est-à-dire l'ordre de succession des stations, et l'état de fonctionnement de l'ensemble du dispositif.

These messages are:

• alarm reading: this message allows the central station to know the alarms collected by the I interfaces of the stations;
• execution of remote controls: this message commands an action in each destination station;
• positioning of warning lights: this message commands the warning lights in each destination station;
• unidentified bytes: this message is sent spontaneously by a station which has not received anything for some time, or which has successively received two unidentified bytes;
• test: this message allows the central station to check that the I interfaces are working properly.
• initialization: this message enables the central station SC to know the configuration of the message loop, that is to say the order of succession of the stations, and the operating state of the entire device.

Following a message sent by the central station, the stations successively insert their response, the message and the responses being received by the central station SC.

FIG. 5 relates to the message reading the alarms.

This message sent by the central station SC consists of two bytes; the first byte REQ is a request for transmission, the second byte is divided into two half-bytes, one of which has a PIL indicator of one bit and three bits at zero, and the other, marked LAL, gives the nature of the message: reading of alarms; following the message the central station SC sends a byte FF which is an end of transmission flag.

This message is received by the first station S1 of the set of n stations. The station S1 transparently transmits the two bytes of the message; the byte FF indicating the end of the transmission, therefore of the message, the station S1 transmits its response following the two bytes of the message transmitted to the central station SC. This response has six bytes, the first of which, with zero value, replaces, as indicated by the arrow f, the byte FF sent by the central station following the message. Following its response, the station S1 sends a byte of value FF which is a flag indicating the end of the transmission.

The next station, S2, receives the first two bytes of the message which it transmits transparently; then it receives the first zero value byte of the response from station S1; this byte indicates the presence of a response; station S2 therefore transmits this byte and the following bytes transparently, and when it receives the end of transmission flag, it inserts its own response following the response from station S1. This response begins with a zero byte which replaces, as indicated by the arrow f, the FF byte; following its response, the station S2 transmits a byte FF which is a flag indicating the end of the transmission.

The following stations do the same; the station Sn, which is the last of the set of n stations, transmits a response whose first byte has a zero value and follows this response with a byte FF which is a flag indicating the end of the transmission.

The central station SC receives from the last station Sn an alarm message consisting of the first two bytes of the transmitted order followed by successive responses from the stations, then the end of transmission flag, that is to say the 'byte FF; he tells her that there are no other answers to wait.

The byte containing the indication FF therefore indicates to a station which receives it that it is the last byte transmitted by the preceding station, and consequently that it can transmit its response which, as indicated, begins with a byte of value null sent instead of the FF byte received. When a station receives a null byte, this byte indicates to it that it is a response from a previous station and that this response must be transmitted transparently.

• un premier octet de valeur nulle,
• un deuxième octet divisé en deux demi-octets ; l'un des demi-octets contient la nature du message, LAL constituant la réponse, et l'autre demi-octet contient quatre indicateurs d'un bit chacun :
  • un indicateur RT qui donne le résultat de l'auto-test de l'interface I,
  • un indicateur CRC qui donne le résultat du contrôle cyclique par redondance sur tous les octets précédents reçus par la station,
  • un indicateur PIL qui indique l'état de l'interface, pilote ou réserve ; cet indicateur a la valeur 1 pour l'état pilote et la valeur 0 pour l'état réserve,
  • un indicateur EST qui signale une erreur sur le format de la trame, le mot trame désignant l'ensemble des octets reçus par une station,
• un troisième et un quatrième octets contenant l'adresse Ad Si de la station,
• un cinquième et un sixième octets contenant l'état des files d'alarmes de la station,
• un septième octet, CRC, contenant la valeur du contrôle cyclique par redondance calculé sur l'ensemble de la réponse de la station.

Each station response consists of seven bytes which are as follows:

• a first byte of zero value,
• a second byte divided into two half-bytes; one of the half-bytes contains the nature of the message, LAL constituting the response, and the other half-byte contains four flags of one bit each:
  • an RT indicator which gives the result of the self-test of the interface I,
  • a CRC indicator which gives the result of the cyclic redundancy check on all the previous bytes received by the station,
  • a PIL indicator which indicates the state of the interface, pilot or reserve; this indicator has the value 1 for the pilot state and the value 0 for the reserve state,
  • an EST indicator which signals an error in the format of the frame, the word frame designating all the bytes received by a station,
• a third and a fourth byte containing the Ad Si address of the station,
• a fifth and a sixth byte containing the state of the station's alarm queues,
• a seventh byte, CRC, containing the value of the cyclic redundancy check calculated over the entire response of the station.

FIG. 6 relates to the initialization message. This message is sent by the central station SC in order to know the configuration of the message loop, that is to say the order of succession of the stations. The initialization message is sent on the initiative of an operator when creating or extending the message loop, or even following a maintenance operation. This initialization message makes it possible to verify that the order of succession of the stations conforms to a configuration file of the message loop. In the event of non-compliance detected by the central station SC, the latter reports a fault on the message loop with, as a parameter, the point of divergence with the configuration file. The initialization process is identical to the alarm reading process, only the format of the responses differs; there is no indication of alarms.

The initialization message includes, like the message of alarm reading a first byte REQ request for transmission, and a second byte divided into two and a half bytes, one of which has three null bits and the PIL indicator, and the other, marked INIT, gives the nature of the initialization message . Following these two bytes, the central station SC transmits an end of transmission flag which is a byte FF.

The response of each station comprises seven bytes, the first of which has the value zero, the second is divided into two half-bytes, one of which marked INIT contains the nature of the response, and the other contains the same indicators RT, CRC, PIL , IS that in the response to an order to read the alarms, the third and fourth contain the address Ad Si of the station which sends its response, the fifth and sixth contain the checksum CS of the software loaded in the interface, contained in a word of the program memory of the microcontroller, and the seventh CRC contains the value of the cyclic control by redundancy calculated on the whole of the response of the station.

Upon initialization, each interface I receiving the initialization message performs its self-test. With regard to the program memory of the microcontroller, the self-test consists in calculating a checksum and verifying that it is identical to that located at the end of the program memory area. The fact of delivering the checksum CS in the response of the station to the initialization message, allows the central station to control the version of the software present in the program memory.

FIG. 7 relates to the remote control execution message which is a message intended for a station identified by its address with indication of the action requested.

• un deuxième octet nul,
• un troisième octet divisé en deux demi-octets dont l'un, repéré TEL, donne la nature du message, ici demande d'exécution d'une télécommande, et l'autre, comporte un bit de valeur zéro, un indicateur PIL d'un bit, et le numéro No TEL, de la demande d'exécution d'une télécommande, sur deux bits, ce numéro étant utilisé en cas de répétition de la demande d'exécution.
• un quatrième et un cinquième octets repérés Ad Si donnant l'adresse de la station destinataire du message,
• un sixième octet, divisé en deux demi-octets dont l'un repéré ACREQ, indique la télécommande demandée dans la station d'adresse Si (ce demi-octet permet de choisir une action parmi plusieurs dans la station Si), et l'autre, repéré T donne le temps d'exécution de la télécommande demandée,
• un septième octet, repéré CRC, contenant la valeur du contrôle cyclique par redondance calculé sur l'ensemble des six octets précédents.

This message begins with a first REQ byte which is a request to send; this byte is followed by the remote control message including:

• a second null byte,
• a third byte divided into two half-bytes, one of which, marked TEL, gives the nature of the message, here a request to execute a remote control, and the other, contains a bit of value zero, a one-bit PIL indicator, and the number TEL, of the remote control execution request, on two bits, this number being used in the event of a repeat of the execution request.
• a fourth and a fifth byte marked Ad Si giving the address of the station receiving the message,
• a sixth byte, divided into two half-bytes, one of which marked ACREQ, indicates the remote control requested in the station with address Si (this half-byte makes it possible to choose one action from among several in the station Si), and the other , marked T gives the execution time of the requested remote control,
• a seventh byte, marked CRC, containing the value of the cyclic redundancy check calculated on the set of the six preceding bytes.

Following the message, a FF byte indicates the end of the message, therefore the end of transmission.

Each station transmits the message transparently, if its station address does not correspond to AdSi. When the message arrives at the destination station, the latter after having detected the FF byte, activates the remote control notified in the message, verifies that it is indeed activated, and then re-issues a response with the BEC indicator (successful execution of the command) positioned at 1; the response is followed by a FF byte.

This response consists in re-transmitting the received remote control message, that is to say the seven message bytes with, in the third byte the BEC and PIL indicators positioned, the BEC indicator corresponding to the zero value bit of the half byte, and in the seventh byte, marked CRC, the value of the cyclic redundancy check calculated by the station; the response is followed by a FF byte.

Of course the response is transmitted transparently by all of the following stations. Following the transmission of a remote control request message, the central station therefore receives the REQ byte it sent, followed by the response bytes sent by the station receiving the remote control message, then by a FF byte. .

Figure 8 relates to the test message. This message, sent by the central station SC, consists of six bytes; the first byte REQ is a request for transmission, the second byte is zero, the third byte is divided into two half bytes one of which marked ESS gives the nature of the message, test, and the other includes a PIL indicator and three bits of value zero; the fourth and fifth bytes contain the address of the central station SC, and the sixth byte, marked CRC contains the value of the cyclic control by redundancy calculated on the set of the five preceding bytes; at the end of the message a byte FF indicates the end of the message. Any Si station which receives this message and which does not detect any anomaly retransmits the message as it is. When a station Sj detects an anomaly it does not retransmit the received message as it is; in this message it replaces the address of the central station with its address and sets the appropriate indicators which allow the central station to determine the origin and type of fault, and in the sixth byte marked CRC the value of the cyclic check by redundancy calculated by the central station is replaced by the value of the cyclic redundancy check calculated by the station Sj.

Then all the stations which receive this message retransmit it as it is, even if they themselves have detected an anomaly; in this way the message from the station Sj is routed to the central station. Thus, unlike the alarm message, the test message does not grow during its progression on the BM message loop.

FIG. 9 relates to the message unidentified bytes; it is transmitted by a station Si when the latter has not received any continuity byte for some time, or when it receives two unidentified successive bytes. In addition to the messages, the central station and the stations periodically send a continuity byte; a station which no longer receives this byte interprets it as an upstream failure. The unidentified bytes message has six bytes; the first byte marked REQ, the second byte is zero, the third byte is divided into two half bytes one of which marked ONI contains the nature of the message sent, unidentified bytes, and the other contains the indicators RT, CRC, PIL , IS positioned by the station, the fourth and fifth bytes marked Ad Si contain the address of the station Si, and the sixth byte, marked CRC, contains the value of the cyclic redundancy check calculated on the previous five bytes; a FF byte is sent following the message.

The following stations retransmit this message without adding a response.

FIG. 10 relates to the message positioning of indicators. This message, sent by the central station SC, is intended for a station identified by its address; the procedure is the same as that of the remote control execution message. The positioning message consists of eight bytes; the first byte marked REQ is a request for transmission, the second byte is zero, the third byte is divided into two half bytes one of which marked PVO gives the nature of the message, positioning of LEDs, and the other includes an indicator PIL and three bits of zero value, the fourth and fifth bytes, marked Ad Si give the address of the destination station, the sixth and seventh bytes, marked CPVO, indicate the alarm indicators whose positioning is requested, and the eighth byte, marked CRC, gives the value of the cyclic redundancy check calculated on the previous seven bytes.

The response from the destination station also has eight bytes; the first and second bytes are identical to the first and second bytes of the message; the third byte is divided into two half bytes, one marked PVO gives the nature of the message, positioning of LEDs, and the other has two bits at zero and two PIL and BEC indicators, the latter indicating the successful execution of the LED positioning request, the fourth, fifth, sixth and seventh bytes are identical to the corresponding bytes of the message, and the eighth byte, marked CRC contains the value cyclic redundancy check calculated on the previous seven bytes; the FF byte is issued following the response.

As indicated above, each interface has its own power supply. Also, any manipulation carried out on a station: plugging in, unplugging, energizing, will cause a disturbance on the entire alarm collection device. This disturbance will be detected by the central station which will then carry out a reset through the BCE loop to realign the entire alarm collection device.

When the n stations of the set of stations are powered up, or following a general reset controlled by the central station via the BCE status control loop, each interface performs its self-test, reads the alarms of its station and prepares, in advance, its response to an order from the central station SC. Each interface then waits for the REQ byte request for transmission; after receiving the REQ byte, it analyzes the next byte. If this byte is not zero, in the case of messages reading alarms and initialization, it gives the nature of the message; if this byte is zero, the interface analyzes the following byte to find out the nature of the message: execution of a remote control, test, unidentified bytes, positioning of LEDs.

Alarm reading message case.

To find out the alarms for each of the stations, the central station periodically transmits the transmission request, REQ byte, followed by a byte containing the nature of the request and then by a FF byte. An interface having received the first two bytes and having thus detected the nature of the order, therefore then receives a null byte or at FF, depending on whether the message is followed by a response or not; when it detects a FF byte this indicates the end of transmission from the previous station. A null byte indicates to the station that it must transmit this byte and the following bytes in transparency; a byte at FF indicates to the station that it must transmit its own response followed by a byte at FF. Following this transmission, the station interface performs its self-test, reads the station's alarms, prepares its next response, and waits to receive a new message.

Case of the initialization message.

As indicated above, this is not a periodic message, but, like the alarm reading message, it is intended for all stations which insert their response one after the other.

Case of the remote control execution message.

When the central station SC wants to command an action in a station, it transmits on the message loop a remote control message, then a byte to FF.

Analysis of the nature of the message contained in the byte following the null byte indicates that it is a remote control request, and the station's interface makes a comparison between its address and that it receives. In case of inequality the message is retransmitted to the next station. In the event of a tie, this indicates that the remote control is intended for the station. Before executing it, the interface checks that it is not seen at fault by its self-test and that the cyclic redundancy check of the message is correct.

The confirmation of the correct execution of the remote control will be made by positioning the BEC indicator (successful execution of the command) in the response to the remote control message. If the central station SC does not receive this confirmation, it repeats its request for a remote control.

When a station has detected a remote control message intended for it, it waits to receive the FF byte which indicates the end of the message; it then issues its response followed by a FF byte. Then the station interface performs its self-test, reads the station alarms, prepares the next response and waits for a new message from the central station.

Case of the test message.

This message is used when the interfaces are in reserve operation; it is issued periodically by the central station. In the case of FIG. 4 where each station has two interfaces I1 and I2, this message is transmitted only on the message loop of the interfaces in reserve. If no interface in reserve detects an anomaly the message is retransmitted as it is.

When a first Sj interface detects an anomaly, it retransmits the message by replacing the address of the central station with its address and by positioning one or more indicators to report the anomaly, or the anomalies, noted, and recalculates the CRC (control cyclic by redundancy); the following stations retransmit this message as is, even if they have detected an anomaly.

Case of the message bytes not identified.

This message is sent spontaneously by an interface which has received no byte after a certain time, or which has successively received two unidentified bytes; the stations located downstream retransmit this message as it is, without adding a response, to the central station SC.

Case of the LED positioning message.

This message is sent by the central station SC to position the warning lights in a station; the message therefore contains the address of the destination station. Any station which receives this message performs a comparison between its address and that which it receives.

All messages include the PIL indicator. This indicator is set when the message is sent; it has the value 1 for pilot operation and the value 0 for reserve operation; it is positioned by the central station, except well heard in the case of the message unidentified bytes since this message is transmitted by a station. Each interface which receives a message checks the state of the BCE state control loop, whose signal has the value 1 for pilot operation and the value 0 for reserve operation, and sets the PIL indicator in its response. function of the ECB loop state. The central station checks for each response the consistency between the state of the BCE loop and the PIL indicator, and in case of divergence the central station SC positions the BCE state control loop in the reserve state, the signal on this loop taking the value 0, and the interfaces pass from pilot to reserve; it should be noted that the divergence may occur when the state of the BCE loop already corresponds to the reserve state and in this case the state of the loop does not change. In the case of FIG. 4, where each station has two interfaces I1 and I2, the change of state of a state control loop causes a change of state of the other loop so that the pilot interfaces pass in reserve and vice versa.

The device of the invention makes it possible to treat anomalies. Any anomaly seen by an interface is signaled to the central station SC by the indicators contained in the response of a station. This allows the central station to locate a fault in the message loop.

Lack of reception.

The absence of reception is checked, at each interface by a continuity byte. The introduction of this byte makes it possible to solve simply all the problems of cut of cord constituted by the loops BM, BCE and BH, as well as the breakdowns in the serial ports of interfaces I and of the central station.

Each interface periodically transmits on the message loop and to the next interface, a continuity byte. When an interface no longer receives this byte or receives two successive unidentified bytes, it takes the initiative to send a message "unidentified bytes". The following stations retransmit the message as is without adding a response; the central station SC can thus locate the interruption, thanks to the address of the station contained in the message it receives.

Fault on a CRC (cyclic redundancy check).

Each interface recalculates the CRC of responses from previous stations. The detection of a CRC fault is signaled to the central station by the positioning of the CRC indicator sent in the interface response. This procedure makes it possible to easily detect and locate the location of the message loop causing the fault.

Frame errors (EST).

These are anomalies seen by the software of the microcontroller of an interface when receiving messages, such as for example no null byte or at FF.

In the event of an error on the frame, the interface which detects it ceases retransmitting all that it receives and sends a response as in the case of a message for reading alarms, in which the indicator EST is set. It then waits for a reset from the central station SC.

Test result (RT)

This indicator is set to 1 by the microcontroller when it considers that the entire interface is in perfect working order. This state is determined by an online test.

Claims (16)

1. A system for collecting alarms from a set of n stations (S1 to Sn) each specified by an address, and each including at least one interface (I) for collecting the alarms of said station; the system including: a central station (SC) where alarms are brought together, and a loop link interconnecting the central station and the interfaces in series; an output of each interface (I) being connected to an input of another interface (I); said loop link comprising: a message loop (BM) conveying messages transmitted by the central station (SC) to at least one of the interfaces, replies from each destination station, and messages emitted by the interfaces to the central station:
      the system being characterized by the fact that said loop link also comprises:

   - a state control loop (BCE) conveying a state control signal delivered by the central station to set an active or a standby operating mode in all of the interfaces, said state control signal having a first value for the active operating mode and a second value for the standby operating mode; and

   - a clock signal loop conveying a clock signal delivered by the central station to all of the interfaces.
2. A system for collecting alarms according to claim 1, characterized by the facts that each station comprises first and second alarm collecting interfaces (I1, I2), that the first interfaces (I1) of the stations are connected in series with the central station (SC) via a first loop link (L1), that the second interfaces (I2) of the stations are connected in series with the central station (SC) via a second loop link (L2), and that the central station delivers a state control signal over one of the loop links to determine active operating mode and a state control signal via the other loop link for determining standby operating mode of the interfaces connected to each of said loop links.
3. A system for collecting alarms according to claim 1 or 2, characterized by the fact that both the clock signal and the state control signal travel in the same direction in each loop link, with messages travelling in the opposite direction to the clock signal and the state control signal.
4. A system for collecting alarms according to claim 1, characterized by the fact that the central station (SC) delivers different types of messages over the loop: alarm read messages destined for all of the stations and transmitted periodically; remote control request messages destined for a particular station in order to perform a remote control operation in said destination station; a set indicator lamp message destined to a particular station in order to set the alarm indicator lamps of said destination station; an initialization message destined for all stations in order to discover the order in which the stations follow one another around the loop link; and a test message destined for all the stations and emitted periodically to discover any anomaly that may have been detected by the interfaces; the remote control request and set indicator lamps messages being transmitted only when the interfaces are operating in active mode; and the test message being transmitted only when the interfaces are operating in standby mode.
5. A system for collecting alarms according to claim 1, characterized by the fact that the central station periodically transmits a continuity byte over the message loop and that an interface which does not receive said continuity byte transmits a non-identified bytes message over the message loop towards the central station (SC), said message including the address of the transmitting station.
6. A system for collecting alarms according to claim 1, characterized by the fact that an interface which receives two non-identified bytes in succession over the message loop (BM) transmits a non-identified bytes message towards the central station (SC), said message including the address of the transmitting station.
7. A system for collecting alarms according to claim 1, characterized by the fact that each message transmitted by the central station includes a flag PIL whose value is determined by the central station as a function of the value of the state control signal in order to indicate the operating mode to which the interfaces are switched by the control signal loop.
8. A system for collecting alarms according to claim 1, characterized by the fact that each reply from an interface and each message transmitted by an interface includes a flag PIL whose value is determined by the interface as a function of the value of the state control signal as received by said interface.
9. A system for collecting alarms according to claim 4, characterized by the fact that the read alarms message comprises a transmission-request first byte (REQ), a second byte split into two half-bytes, one of which specifies the type of the message and the other of which contains three zero value bits and a 1-bit flag PIL whose value is determined by the central station as a function of the value of the state control signal; that an end-of-transmission one byte flag FF is transmitted following said message; that a reply to said message comprises: a zero value first byte; a second byte split into two half-bytes, one of which specifies the "read alarms" type of the reply, and the other of which comprises four 1-bit flags, namely a flag RT for the result of an autotest performed by the station interface, a flag CRC for the result of a cyclic redundancy check on the message and the replies as received by the station, a flag PIL for specifying the operating mode corresponding to the state control signal as received by the station, and a flag EST for indicating a framing error; third and fourth bytes containing the address of the station; fifth and sixth bytes for indicating the alarms of the station; and a seventh CRC byte for specifying the value of the cyclic redundancy check calculated on the reply of the station; that a first station receiving the message removes the end-of-transmission flag; following the message and inserts its reply following the message after which it adds its own end-of-transmission flag, and that thereafter each station removes the end-of-transmission flag following the preceding reply, inserts its own reply, and inserts its own end-of-transmission flag.
10. A system for collecting alarms according to claim 4, characterized by the facts that the initialization message comprises: a transmission-request first byte (REQ); a second byte split into two half-bytes, one of which specifies the type of the message and the other of which contains three zero value bits and a 1-bit flag PIL whose value is determined by the central station as a function of the value of the state control signal; that a one byte end-of-transmission flag FF is transmitted following said message; that a reply to said message comprises: a zero value first byte; a second byte split into two half-bytes, one of which specifies the initialization type of the reply and the other of which comprises four one byte flags: a flag RT for the result of an autotest performed on the interface of the station, a flag CRC for the result of a redundancy check on the message and the replies received by the station, a flag PIL for specifying the operating mode corresponding to the state control signal as received by the station, and a flag EST for indicating a framing error; third and fourth bytes containing the address of the station; fifth and sixth bytes (CS) specifying the value of the check sum on the software stored in memory; and a seventh byte (CRC) for specifying the value of the cyclic redundancy check calculated on the reply of the station; that a first station receiving the message removes the end-of-transmission flag following the message, inserts its reply after the message, and adds its own end-of-transmission flag; and that thereafter each station removes the end-of-transmission flag following the preceding reply, inserts its own reply, and adds its own end-of-transmission flag.
11. A system for collecting alarms according to claim 4, characterized by the facts that the remote control message comprises: a transmission-request first byte (REQ); a zero second byte; a third byte split into two half-bytes, one of which specifies the remote control type of the message and the other of which specifies the number of the request, provides a zero bit, and provides a 1-bit flag PIL whose value is determined by the central station as a function of the value of the state control signal; fourth and fifth bytes containing the address of the station; a sixth byte split into two half-bytes, one of which specifies the requested remote control and the other of which specifies an execution time therefor; and a CRC seventh byte for specifying the value of the cyclic redundancy check calculated on the bytes of the message; that a one byte end-of-transmission flag is transmitted after said message; and that the destination station replies by relaying the message with the third byte containing the flag PIL set by the station to specify the mode of operation which corresponds to the state control signal as received, and a flag BEC replacing the zero value bit in order to specify that the remote control message has been properly executed, and in the sixth byte the value of the cyclic redundancy check as calculated on the reply, and then retransmitting the end-of-transmission flag.
12. A system for collecting alarms according to claim 4, characterized by the facts that the test message comprises a transmission-request first byte (REQ); a zero value second byte; a third byte split into two half-bytes, one of which specifies the type of message and the other of which contains three zero value bits and a 1-bit flag PIL whose value is determined by the central station as a function of the value of the state control signal; fourth and fifth bytes containing the address of the central station; and a CRC sixth byte specifying the value of the cyclic redundancy check calculated on the bytes of the message; that a one byte end-of-transmission flag is transmitted after the message; that a station which has detected no anomalies relays the message and the end-of-transmission flag; and that a station which has detected an anomaly and which receives said test message transmits a reply comprising a transmission-request first byte (REQ) which replaces an end-of-transmission flag as received by the station; a zero value second byte; a third byte split into two half-bytes, one of which specifies the type of the reply and the other of which comprises four 1-bit flags: a flag RT for the result of an autotest on the station interface; a flag CRC for the result of a cyclic redundancy check; a flag PIL for specifying the operating mode which corresponds to the state control signal as received by the station; and a flag EST for indicating a framing error; fourth and fifth bytes for specifying the address of the station; and a sixth byte for giving the value of the cyclic redundancy check calculated on the bytes of the station's reply; and that an end-of-transmission flag byte is transmitted following the reply.
13. A system for collecting alarms according to claim 4, characterized by the facts that the non-identified byte message transmitted by a station comprises a transmission-request first byte (REQ); a zero value second byte; a third byte split into two half-bytes, one of which specifies the type of the message and the other of which comprises four 1-bit flags: a flag RT for the result of an autotest on the station interface; a flag CRC for the result of a cyclic redundancy check on the received bytes; a flag PIL for specifying the mode of operation which corresponds to the state control signal as received by the station; and a flag EST for indicating a framing error; fourth and fifth bytes for giving the address of the station; and a sixth byte for giving the value of the cyclic redundancy check calculated on the bytes of the reply; and that an end-of-transmission flag is transmitted after the message.
14. A system for collecting alarms according to claim 4, characterized by the facts that the set indicator lamps message comprises a transmission-request first byte (REQ); a zero value second byte; a third byte split into two half-bytes one of which contains the type of the message and the other of which contains three zero value bits and a 1-bit flag PIL whose value is determined by the central station as a function of the value of the state control signal; fourth and fifth bytes giving the address of the destination station; sixth and seventh bytes for specifying which alarm indicator lamps are to be switched on; and an eighth byte giving the value of the cyclic redundancy check calculated on the bytes of the message; that an end-of-transmission flag is transmitted following the message; and that the destination station replies by retransmitting the message with the flag PIL in the third byte being given a value by the station to specify the mode of operation which corresponds to the state control signal as received thereby, and with a zero value 1-bit flag BEC whose value is determined to indicate that the set indicator lamps message has been properly executed; and with an eighth byte containing the value of the cyclic redundancy check calculated on the reply, and then retransmitting the end-of-transmission flag.
15. A system for collecting alarms according to claim 1, characterized by the facts that each interface of a station comprises a microprocessor (mP) and a parallel/series register (1) having a parallel input connected to the output of an AND gate (2), an output connected to a data input (D) of the microprocessor, and a clock input connected to a clock output (h) from the microprocessor; that the AND gate has an input connected to the station via an alarm link (AL) and another input connected to a write output (W) from the microprocessor; and that the microprocessor has a station address input connected to a station address circuit (3) containing the address of the station, a receive input and a transmit output connected to the message loop (BM), a remote control output connected via a remote control link (LC) to the station, a clock input (CLK) connected to the clock signal loop (BH), and a state control input connected to the state control signal loop (BCE) connecting the central station to the station interfaces and conveying the state control signal delivered by the central station.
16. An alarm collecting system according to claim 15, characterized by the fact that the interface further includes an alarm output circuit (5) having its output connected to the alarm link (AL) and having its input connected to the output from an AND gate (6) having a first input connected to the data input (D) of the microprocessor, a second input connected to the write output (W) of the microprocessor, and a third input connected to a control output (CV) from the microprocessor, said alarm output circuit serving to test the alarm link during operation of the interface to collect alarms, and to transmit signals over the alarm link for setting alarm indicator lamps during operation of the interface for setting alarm indicator lamps.

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