SYSTEM AND METHOD FOR TRANSFERRING STATUS INFORMATION BETWEEN A PLURALITY OF STATUS SITES

Abstract: A pulse generator (4) is coupled by a common conducting path (2) to sending status sites (1) and receiving status sites (40). Each sending status site (1) comprises at least one information bit to be transferred out; each receiving status site (40) comprises at least one memory bit to be resided by an information bit. Each information bit and memory bit is assigned an addressing number (N1, N2 ... Nm). The pulse generator (4) provides the conducting path with a sequence of pulses each of which is counted for identifying its appearing order among the sequence of pulses. When the conducting path (2) is coupled with an information bit, the status (P1, P2 ... Pn) of the information bit determines, on the conducting path, the appearing characteristic of the pulse associated with the information bit. When the conducting path (2) is coupled with a memory bit, the characteristic of the pulse determines the content of the memory bit associated with the pulse, consequently the status of an information bit determines the content of the memory bit associated with a pulse which is associated with the information bit.

Description: TITLE OF THE INVENTION System and Method for transferring Status Information between a Plurality of Status Sites TECHNICAL FIELD The present invention is generally related to data transferring systems, and particularly to monitoring and/or retrieval of information from a plurality of sensors, message centers or the like which may be in dispersed locations. BACKGROUND ART When communicating digital information, i.e. information represented in a discrete binary form, the digital message or data is conventionally sent from one location to another by converting the message or data into a serial signal for transmission. When received, the incoming serial binary information is transformed back into parallel form for processing and/or storage. The parallel-to-serial and serial-to-parallel conversions require converting hardware and means for causing the transmitting system to operate in a synchronous or asynchronous mode. One ' disadvantage of using such hardware is that it's usually not small enough for a conventional sensor to accommodate. The present invention generally provides a means for transmitting status information from one sending location to another receiving location without the need for conventional parallel/serial conversion devices. Stored information or status indications, typically in binary form, can be transferred from remote and dispersed locations, such as a group of sensors or message centers, to a plurality of monitoring stations/receiving status sites/message collectors, using relatively simple circuits and using relatively little cabling: A single conducting path coupling all of the sending status sites and all of the receiving status sites/stations are all that is required. The invention also has the particular advantage that there is no requirement for synchronization (or an asynchronous operation) between the transmitting devices and receiving devices, thereby eliminating system stability problems. The invention further permits stored information to be transmitted randomly, thereby yielding a system which is less susceptible to being compromised, that is, a system which provides greater security against outside tampering. One additional advantage of the invention is that there is no need of a master station for a system transferring data from a plurality of senders to a plurality of receivers. As mentioned, the present invention can be used for the central monitoring of a large number of dispersed sensors and this can be done on a single conducting path such as a parallel circuit l'inking the sensors. A prior monitoring system for monitoring sensors on a single parallel circuit is described in U.S. Patent No. 4,485,373, wherein each of the sensors has an associated resonant circuit tuned to different frequencies and wherein the open or closed condition of the different sensors can be detected by applying a swept frequency signal on the sensor line and observing voltage dips on the line for the various frequencies to which the sensors are tuned. However, such a frequency-dependent monitoring system is relatively complicated to implement and has other drawbacks. One drawback is the difficulty of using such a system with a large number of sensors. The system of patent No. 4,485,373 is driven by a voltage of controlled oscillator (VCO) and where, for example, 240 sensors are to be monitored and 24 volts DC is the maximum voltage of the power supply, the voltage increments between two levels of the controlled voltage to the VCO can be as small as 0.1 volts (because 240 different frequencies are needed). Thus, for the system to work properly the system noise level must be controlled to well below 0.1 volts. In the present invention such noise level limitations and the instabilities arising therefrom are greatly reduced. The other problem with the above frequency-dependent monitoring system is the limitation of the number of resonant frequencies, and therefore the number of associated sensors. This problem arises from the requirement that the separation between every two resonant frequencies must be large enough so that the impedance of each resonator, at its resonant frequency, seen from the monitoring station, is significantly different from that of the combination of all the other parallel resonators at that frequency. Otherwise one resonator will not be distinguishable from another. The requirement for a substantial separation between adjacent frequencies will, for a large number of sensors, result in a large difference between the lowest frequency and the highest frequency of the sweep signal. This in turn will result in a significant difference of attenuation between the signal of highest frequency and that of the lowest frequency. Frequency separations of resonant sensor circuits can be a serious problem if the detector is too sensitive. A less sensitive detector could be used, but only by using a wider spread of frequencies, or by increasing the quality factor of the resonator to a very high level. However, the resonator of a very high quality factor will raise the manufacturing cost and also may increase the chance that the system is compromised through paralleling the system by a system of the same specification, because the impedance of the resonator at its resonant frequency is too small to be distinguished from that of two paralleled resonators of the same specification. In short, there are very difficult design problems in devising a practical frequencydependent system as disclosed in patent No. 4,485,373, examples of which have been given above. Reference is again made to patent No. 4,485,373, and specifically to the description therein at column 4, Lines 20-44 wherein that resonant circuits associated with the sensors are replaced by a unijunction transistor switch and an RC circuit for generating a time delayed pulse on the detector circuit in response to a voltage applied to the detector circuit. While overcoming some problems of the resonant frequency design, this time based approach has a significant disadvantage: setting up the system and creating a profile of the time delayed pulse responses would be relatively complicated and time consuming. This is especially so if a large number of sensors are to be monitored. The present invention provides a system and method for monitoring a large number of sensors without the need to create a response profile, and without the need of time consuming pread ustments or calibrations. Hence the implementation of the invention is relatively easy. DISCLOSURE OF THE INVENTION In accordance with the invention, a system for transferring status information between a plurality of status sites includes a means for applying a sequence of pulses to a conducting path coupling each of the status sites and a means associated with each of the status sites for discriminating between the pulses in the sequence of pulses. Further means are provided whereby each of the status sites responds to one of the pulses within this sequence in such a way that the monitorable condition/information bit of the monitored/sending status site determines the appearing characteristic of the pulses on the conducting path. For example, the contact of a contactor or the level of an information bit such as the voltage level of a binary bit at a monitored status site determines the amplitude of the pulses associated therewith. Hence the status (on or off) of the contact or the status (high level or low level) of the information bit can be recognized by observing the amplitude of the pulse associated with the contact/information bit. In the embodiments illustrated herein the pulses are, electrical pulses, and in particular voltage pulses, and are applied to a conducting path to which the status sites are coupled. Also the pulses are described as being countable by counting means associated with each of the status sites. However, it is understood that the invention is not limited to electrical pulses or pulses that are counted, rather the invention could be implemented using any distinguishable pulse including non-electrical pulses, such as acoustical pulses, pressure pulses, magnetic pulses or pulses of electro-magnetic wave or energy. Also, pluses might be distinguished by amplitude or pulse widths or some other characteristics. In the illustrated embodiments the monitored/sending status sites are coupled by a common conducting path to the pulse generator, the conducting path in turn is coupled to either proximate or remote detection means such as monitoring stations or means such as receiving status sites/message collectors for storing status information. Associated with each status site is a counting means which is connected for counting a sequence of pulses applied to the conducting path and to cause the monitorable condition/information bit of the monitored/sending status site to be coupled to the conducting path for detection in response to a preset pulse count. Each monitorable condition/information bit is associated with a different preset pulse count so that it responds to a different pulse within the sequence of pulses by determining the pulse's appearing characteristic on the conducting path. By resetting the counting device the monitored/sending status sites can continue to respond to the pulse counts in a continuous sampling operation. Consequently the pulses carry not only addressing information but also status information composed of the status of the monitorable conditions/information bits of all monitored/sending status sites. At the monitoring stations/receiving status — o — sites/message collectors the status information carried by the pulses is recognized by counting the pulses and observing the appearing characteristics of the pulses associated respectively with each monitorable condition/information bit, and then the discriminated status of each monitorable condition/information bit is, for example, indicated by a lamp in the monitoring station or stored in a memory bit of the receiving status sites/message collectors. It can be seen that neither synchronization nor asychronous operation is required in regard to the pulsing of the system provided by this invention. Completely random pulses (such as can be generated by a R-S flip-flop circuit) can be used wherein the system is responsive only to the sequence order of the random pulses. This feature would provide great advantages to a user concerned with the security of the system and desiring to prevent the system form being compromised by attempts to monitor or override the carrier signal of the status information. It is therefore a primary object of the invention to provide a system and method for retrieving status information (such as binary data or messages) from a plurality of monitorable status sites that is relatively simple to use, is implemented inexpensively, and has good reliability. It is also an object of the invention to provide a system and method for transferring status information between a plurality of status sites that is based on neither frequency division nor time division and therefore requires neither synchronous nor asychronous operation between the status sites. It is a further object of the invention to provide a system and method for transferring status information between a plurality of status sites without need of a master station for coordinating the interacting operation among the status sites. The foregoing objects are not exclusive and further objects of the invention will become apparent from the drawings and the description herein of the illustrated embodiments. BRIEF DESCRIPTION OF THE DRAWINGS FIG. la, is a general circuit drawing illustrating the basic operating principles of the invention. FIG. lb is a series of waveforms illustrating the different pulse shapes that may be generated by the pulse generator (4) illustrated in FIG. la. FIG. le is a possible series of wave forms representing responded pulses in response to the applied waveforms shown in FIG. lb. FIG. 2 is a block diagram of a system in accordance with the invention showing a plurality of status sites in the form of sensors interconnected by parallel circuit and having a detection circuit together with the system's pulse generator. FIG. 3 is a schematic drawing of the system shown in FIG. 2 in block diagram form. FIG. 4 is a schematic drawing of a simplified version of the schematic circuit illustrated in FIG. 3. FIG. 5 is a schematic drawing of the line integrity checking circuit T shown in FIGS. 3 and 4. FIG. 6 is a schematic drawing showing another aspect of the invention wherein the monitoring station is a remote monitoring station which stores the monitored status site information in accordance with the sequence order of pulses appearing on the conducting path. FIG. 7 is a schematic drawing illustrating a status site counter and switching circuit for monitoring a plurality of conditions. FIG. 8 is a schematic diagram illustrating one example circuit embodiment of the counting device 11, logic circuit 12, and switching circuit 13 illustrated, for example, in FIG. 3. FIG. 9 is a schematic diagram of one form of the interpreter 6 shown in FIG. 2. MODES FOR CARRYING OUT THE INVENTION Referring now to the drawings, FIGS. la-c generally illustrate the basic operating principle of the invention. As shown in FIG. la, a plurality of spatially dispersed status sites 1 having monitorable conditions Cx , C2 , .... , C B are coupled by a conducting path 2 to a means for detecting the monitorable conditions which are two monitoring stations 40. Switching means in the form of switches Wi , 2 , .... , W n associated with each of the monitored/sending status sites (abbreviated as "status sites" hereinafter) selectively connect the monitorable conditions Ci , C2 , ...., Cn to the conducting path. The switches are actuated by circuits CL which, as hereinafter described, comprise a counting device and a logic circuit. A pulse generator 4 is connected through resistor Rg to the conducting path 2 for the purpose of applying a sequence of the pulses to the conducting path and therefore to each of the status sites. With further reference to FIG. la, it will be seen that the counting device of each of the circuits CL associated with each of the status sites counts the pulse on the conducting path 2, and that the logic circuit is so designed that the output of the circuit CL will actuate the switch of the circuit to an "on" condition only during the period when the sequence order number of the pulse counted equals a predetermined integer. As an example, suppose the switch associated with the monitored condition Cm (where m = any of the integer numbers 1, 2, ...., n) is assigned a predetermined integer M and suppose the counting device associated with this switch is reset before time to . If from time to onward a sequence of pulses, such as a sequence of pulses shown in FIG. lb, is applied to the conducting path 2 by the pulse generator 4, then right after the falling off of the (M-l)th pulse the number of pulses counted by each of the counting devices of circuit CL will equal M-l. The counting device of the Mth status site having the associated switch W m and the monitorable condition Cm will then cause the switch W m to be on during the period of the Mth pulse and the resulting pulse waveform appearing on the conducting path 2 will depend on the monitored condition. C« . FIG. lc generally illustrates an example of types of pulse waveforms that might appear on the conducting path subjected to the effect of being responded by the monitorable conditions of the status sites. To illustrate how pulses appear subjected to the effect of being responded by the Mth status site, consider that the monitored condition Cm of the the Mth status site is a simple electrical contact. The amplitude of the responding Mth pulse will be zero if the contact is closed during the period of the Mth pulse since the pulse is shorted to ground. On the other hand, if the contact is open, the pulse on the conducting path will experience no change; the monitorable condition will be seen at the conducting path as an open circuit. Generally, it will be understood that in order for the counter of circuit CL to count each pulse on the conducting path, the amplitude and the pulse width of every responded pulse must meet certain threshold requirements for triggering the counter. Hence the information retrieving system must be so designed that each pulse, after being responded to by a monitorable condition of a status site, can still be counted by all the counting devices. For example, if the status of the monitored condition of the status site is the opening or closing of a contact, a resistance in series with the contact will be needed to produce a responded pulse waveform that can be counted by all status sites. So long as every pulse on the conducting path can be counted, the circuit CL of each status site can keep track of the sequence order of each pulse among the sequence of pulses, and, at the appointed time, can respond to its designated pulse. If each monitored condition of each status site responds to at least one pulse of the sequence of pulses, the responded sequence of pulses on the conducting path 2 will contain the sampled information about the status regarding each of the status sites. It will be evident from the circuits described below that the monitored condition of the status site is not necessarily the contact such as used in the foregoing example, and that the series resistance will not in all cases be necessary. The only criterion is that the monitored condition responds to its associated pulse in such a way that the responded pulse on the conducting path can be observed from another location and that a pulse be responded on the one hand capable of being counted for identifying its sequence order and on the other hand having at least two pulse waveform states capable of being distinguished for detecting the status of a monitorable condition. At the monitoring station, each pulse appearing on the conducting path 2 is observed for checking both waveform state and sequence order for recognizing the status of the monitored condition associated with the particular sequence order of the pulse. As will be described, the sequence order of the pulses can be determined at the monitoring station by means of a counting device. As long as the counting device associated with every monitored condition is reset at the same time as the counting means at the monitoring station, the status of each monitored condition can be correctly recognized at the monitoring station. However, as will be discussed in more detail below, there may be several ways of recognizing the status of the monitored condition such as the scheme of detection illustrated in the FIGS. 3 and 4 embodiments of the invention, wherein the responded sequence of pulses on the conducting path 2 are compared with the pulses applied directly to the conducting path by the pulse generator. It will be evident from the following described circuit implementations of the invention that other schemes can be devised to carry out the basic principles of the invention. The circuit of FIG. 2, shows a system in accordance with the present invention wherein the pulse generator 4 is part of the monitoring station 40 (designated as' 40a in this figure) which serves as the means for detecting the monitorable condition of the several status sites 1. In the monitoring station 40a, the pulse generator 4 and the conducting path 2 are both inputted to an adaptor circuit 3 which adjusts the input to the detector 5 so that the detector can correctly recognize the waveform status of the pulses responded by the monitored status sites and appearing on the conducting path without being restricted by either the environment or the stability of the pulse generator. The pulse generator 4 generates a sequence of pulses that are applied to the conducting path and detector 5 through the adaptor circuit 3, from whence the sequence of pulses will in turn be applied to each of the monitored status sites. Because of the specific function provided by the adaptor circuit 3, which is more fully described below, the stability of the amplitude and frequency of the pulse generator 4 is not important as long as the pulse width and the pulse amplitude can keep the electronic circuit operating normally. For example, a random wave, e.g., a train of irregularly spaced pulses, can be used which have the aforementioned advantages of providing a system that cannot readily be compromised. Basically the amplitude of the pulse waveform on the conducting path 2 will be a function of the status of the monitored condition of the status sites 1, the number of pulses received by the status sites after the system is reset, and the count number assigned to the status sites. Further in reference to FIG. 2 , the basic function of the adaptor circuit 3 and detector 5 is to produce an output from the detector that depends on the comparison between the pulses appearing on the conducting path subjected to the responding of the monitored status sites with the pulses received directly from the signal generator. The output of the detector and the output from the pulse generator are in turn connected to an interpreter 6, the basic function of which is to match the detector output and the sequence order of the pulses from the pulse generator 4 in reference to a reset time, and to use this matching to distinguish the status of each monitored condition of each status site coupled to the conducting path. Using the signal from the interpreter 6, interface 7 will enable a human being or a machine to recognize and/or record the individual status of the monitorable conditions/information bits of the plurality of monitored status sites. For example, this interface may be a plurality of lamps or LED displays for indicating individual status of the monitored conditions, or may be a peripheral device of a computer for reading the content (or status) of information bits into memory bits. FIG. 3 shows a circuit implementation of the more general circuit illustrated in FIG. 2. Referring to the FIG. 3 circuit, each of the status sites 1, has associated with it a counting device 11 connected to a logic circuit 12, the output of which is used to trigger a switching circuit 13 for coupling the monitorable conditions represented by contacts SWi and SW 2 with the conducting path 2. The contacts are either open or closed depending on the monitored phenomena or event and can be the outputs of many sensing devices such as pressure, electricity, light and temperature threshold detectors. One of the contacts, SWi , is provided with a series resistance Rx for the purpose of keeping responded pulse's amplitude above a minimum when the switching circuit 13 is closed. In this figure SWi is N.C while SW 2 is N.O. The adaptor circuit 3 of FIG. 3 includes a voltage dividing network comprised of resistors R , Rs , Rε , R7 , and Rt and rheostats Ri , R2 , and R3 for adjusting threshold voltage inputs to the detectors 51 and 52. A wave follower 3Wf and switches SCi and SC2 are provided for adjusting the threshold voltages for each multiple of pulses as determined by the wave follower 3Wf . The wave follower can be implemented by a combination of a counter and logic circuitry as would be known by a person skilled in the art. The detector 5 generally comprises two comparators 51 and 52 and time delay elements, such as the capacitors illustrated in dash lines connected to the detector outputs. In the FIG. 3 embodiment, it is noted that the comparator's output voltage is high when the voltage at the positive input terminal is higher than the voltage at the negative input terminal, and otherwise is low. Such a comparator can be implemented with commercially available chip such as the LM339 by National Semiconductor. The interpreter 6 of FIG. 3 generally comprises a counting device 6a and a logic circuit 6b. The outputs xi .... , x n and yi ... y n of the logic circuit, represent one of two possible contact states for each of the n status sites. To illustrate the operation of the FIG. 3 circuit, assume that the monitored status sites can be represented by a group of sensors Si , S2 , .... Sm each of which is assigned an integer number. Let a sequence of numbers Ni , 2 .... Nm be assigned to these sensors, i.e. the number Nk is assigned to sensor Sk for k=l, 2, .... , m. Also assume that Ni < N 2 .... < Nm and that all counting devices in the system are reset at t=0, and further that the pulse generator starts to generate a sequence of pulse signal at t=0. The switching circuit 13 of sensor Sk will be turned on for one pulse period when the number of the pulses counted by the counting device 11 of Sk corresponds to Nk • This is true for k=l, 2, ...., m. Thus, sensor i will have its circuit nodes S a and Sb short-circuited by switching circuit 13 during the period of the Nith pulse. Likewise, sensor S2 will have its circuit nodes S a and Sb short-circuited by switching circuit 13 during the period of the N2th pulse, etc. It is noted that the wave follower 3Wf in the FIG. 3 circuit will close switches SCi and SC2 during the period of the Nkth pulse, so that during the Nkth pulse the resistors Re and R 7 will be short-circuited. To provide suitable inputs to the comparators 51 and 52 from the circuit nodes 3a, 3b, and. 3c the following design criteria should be met: Let the amplitude of the pulses at circuit nodes 3a, 3b, 3c, and 4a equal A3a , A3t > , A3c , Av» The resistors Ri , R2 , R 3 , 4 , R5 , Re , R 7 , Rt , Rx , are then designed to satisf the following equations: (a) A (R7+R5 )/(R 3 +Rs+R7 ) - A w Rt/(Rι+Rt ) > max. noise amplitude. (b) AwRt/(Rι+Rt ) - Aw (R 4 +Re )/(R +R 2 +R 6 ) > max. noise amplitude. (c) AwRt/CRx+Rt ) - AwRs/(R3+Rs ) > max. noise amplitude. ( d) Aw (Rχ//R t )/(Rι+R x //Rt ) - AwR 4 /(R 2 +R 4 ) > max. noise amplitude. ( e ) AwR 5 / (R 3 +R 5 ) - Aw (R * //Rt ) / (Ri +R X //Rt ) > max . noise amplitude . ( f ) AwR 4 / (R2 +R ) > max . noise amplitude . ( g ) AwRt / (Rι +Rt ) < max . rating of power supply voltage of counting device 11 ( h ) Aw (Rχ //R t ) / ( R x +R x //Rt ) > minimum high level input voltage of counting device 11 . For further explanation, note that the following equations: (i) A 3 b = Aw(Rs+R7 )/(R3 +R5+R7 ) (j) A 3c = Aw(R 6 +R )/(Rϊ +Re+R ) (1) As b - A3 a > max. noise amplitude, (m) A3 a - A3c > max. noise amplitude. are satisfied during the period of the Kth pulse for every K not equal to any one of the sequence of number Ni , N2 , ... Nm because the switches SCi and SC2 of adaptor circuit 3 and the switching circuit 13 of each status site is opened during this period, and A3 a should be higher than A3 c while lower than A3 b so as to keep the output of detector 5 lower than A3b so as to keep the output of detector 5 unchanged. Assuming instead that L represents any one of the numbers Ni , N2 .... , Nm , then during the period of the Lth pulse the following equations will apply: Now if sensor Si has its contacts SWi and SW2 unchanged then the amplitude at node 3a is: (p) A 3a = Aw(Rt//Rχ)/(Rχ+Rt//Rχ) But if sensor S L has its contact SWi open while contact SW2 remains unchanged, then this amplitude is: If sensor SL has its contact SW2 closed while contact Slύ remains unchanged then: (r) A 3a = 0 These result from that the switching circuit 13 of sensor SL and the contacts SCi and SC2 are turned on during the period of the pulse counted as NL. It will ' also be seen that during the duration of the Lth pulse the following equations apply: (s) A3 b - A3 a > max. noise amplitude, and (t) A3a - A3c > max. noise amplitude if sensor SL has its contacts SWi and SW2 unchanged, (u) A3a - A3b > max. noise amplitude, and (v) Asa - A3 c > max. noise amplitude if the sensor SL has contacts SWi open while contact SW∑ remains changed. Also, (w) A3c > max. noise amplitude, and (x) A3b > max. noise amplitude, if sensor Si has contact SW 2 closed while contact SWi remains unchanged. It can be seen that equ. (s) implies equ. (x) , and that equation (t) implies equ. (v) . The solution for the above equations where the maximum noise amplitude = 0.5 volts, Aw = 15 volts, the min. high level input voltage of the counting device 11 = 7 volts, and max. rating of supply voltage ' of counting device 11 = 10 volts is as follows: Ri = 10k, R 2 = 10k, R 6 = 5k, R = 2k, R3 = 10k, R 7 = 30k, R 5 = 15k, Rx = 30k, and R t = 20k. Where the conditions of equations (i), (j), (k) , (1), and (m) are satisfied, comparators 51 and 52 will have their outputs at a high level during the period of the Kth pulse for K not equal to any one of the numbers Nj , N2 .... , N m . During the period of the Lth pulse for L being any one of the numbers Ni , N 2 , .... , N m the condition that equations (n) , (o), (p), (s), (t) are satisfied can also guarantee the high level output status of comparators 51 and 52 for the condition that the sensor SL has its contacts unchanged. However equations (n) , (o), (q), (u) , (v) , will lead to a low level at the output of comparator 51 but a high level at the output of comparator 52. On the other hand, equations - 1 I — (n), (o), (r), (w) , (x), lead to a low level at the output of comparator 52 while maintaining a high level at the output of comparator 51. From the above discussion, it can be recognized that the output of the detector 5 is a function of the status of the sensor Sk during the period of the Nkth pulse for every K = 1, 2, ...., m. The logic circuits 6b distinguishes the individual status of the monitored sensors by managing the output of the detector 5 and the output of the counting device 6a as previously discussed. For example, one way to inform the interface 7 of the status of sensor Sk is to turn on the output line Xk of logic circuit 6b at the moment when the output of counting device 6a rises to a status in response to the Kth pulse, and the output of comparator 51 falls to a low level in response to the status of sensor Sk when the sensor's contact SWi is open and the contact S ∑ remains unchanged. On the other hand, the output line Yk would be turned on after the output of counting device 6a rises to a status in response to the Kth pulse, and the output of comparator 52 falls to a low level in response to the status of sensor Sk when the Sk sensor's contact SW2 is closed and the contacts SWi remains unchanged. Consideration is now given to the design of the wave follower circuit 3Wf for closing the switches SCi and SC2 follower circuit 3Wf for closing the switches SCi and SC2 during the period of the Kth pulse for K equal to any one of the number Ni , N2 .... N m • A preferred way of doing this is to assign the number to the sensors such that Ni = L, N∑ = 2L, N3 = 3L, .... Nm = mL, where m, L are integers. By assigning the sensors every Lth number the counting device in the 3Wf circuit can be reset right after every L pulses, and can turn on the switches SCi and SC2 right after the falling of the (L-l)th pulse, and turn off the switches again right after the the falling of the Lth pulse. This process can be repeated every L Pulses. Another type of the wave follower 3Wf is that it turns the switches SCi and SC ∑ on right after the beginning of the Lth pulse rather than the falling of the (L-l)th pulse. Of course, if the wave multiplier L=l, that is, if each of a group of sensors is assigned one of the sequence of integers 1, 2, 3, ...., m, then the switches SCi and SC∑ and the wave follower circuit 3Wf would no longer be needed. This is because the switches are short-circuiting resistors Re and R 7 for each pulse and therefore, these resistors can simply be removed. Such simplified circuit design is illustrated in FIG. 4. In the FIG. 4 embodiment the selection of the resistance values for Ri r 2 , R3 , 4 , Rs , and Rx is similar to that described for the FIG. 3 circuit, though the conditions are now somewhat simplified. FIG. 5 illustrates a line integrity checking circuit T which would be an optional feature. This circuit can be added for checking conducting path integrity between the status sites and monitoring stations, and, for example, can be added to the circuits shown in FIGS. 3, 4, 6 and 7. If the conducting path has a fault of being opened, all of the status sites behind the opening point will be seen at the monitoring station as if they are removed, even though their contacts SWi and SW2 remain unchanged. By placing the integrity checking circuit T at the furthest site, this condition can be readily detected. The approximate location of an open circuit can be estimated from the monitoring station by recognizing the sequence order of the pulse after which all remaining status sites appear as if they are removed. In FIG. 6, circuit 40b represents one form of a monitoring station/receiving status site/message collector such as 40 illustrated in FIG. la. A sequence of pulses are generated by pulse generator 4, and such pulses are responded by the status sites 1 so as to carry the status information of the status sites' monitored conditions/information bits. Each of the responded sequence of pulses received by monitoring station/receiving status site/message collector 40b is coupled to its associated detecting device Dα , D 2 , D3 , .... , D n through its associated switching device Wi , W2 , W3 , .... W n . The switching devices are turned on by a suitable counting device 6a and logic circuit 6b during the period of the received responding pulse associated with that switching device. Thus, the monitoring station/receiving status site/message collector 40b operates to take the pulse encoded information off the conducting path 2 in a manner substantially the reverse of the technique for placing that information on the conducting path at the status sites. To further illustrate the operation of the 40b circuit of FIG. 6, it is observed that the first pulse of a sequence of pulses is coupled to detecting device Di by switch Wi . Similarly, the Kth pulse is conducted to the Kth detecting device Dk by switch Wk for k = 2, 3 ...., n. Each of the ' detecting device Di , D2 , .... , D n is so designed that it can recognize the status information contained in its associated pulse. For example, each of these detecting devices may include a circuit similar to adaptor circuit 3 and detector 5 of the FIG. 4 circuit embodiment. It can be seen that the circuit 40b has the same function as the monitoring station of FIG. 4. The structure difference is that in FIG. 4 only one dectector instead of detecting device Di , D2 , ...., D D is used, and the detector's outputs are connected as inputs to circuit 6b which implicitly comprises the combinational functions of switches i , W2 , .... , Wn and circuit 6b of FIG. 6. FIG. 7 shows an alternative con iguration for the circuits of the status sites la and lb, where each of the status sites has many conditions to be- monitored. In each of the illustrated status sites la and lb the counting device 11 and logic circuit 12 are the same as those in FIG. 4, except that they now must be able to turn on many- switching circuits W , W2 , .... , W n instead of only one switching circuit. During the response period for the status site the associated multiple switching circuits of the status site can be sequentially turned on and off to respond multiple conditions to the conducting path. In this manner a message represented in a digital form or coded by the status of the conditions Ci , C2 , .... , C n can be responded to the conducting path. As illustrated in FIG. 7 the message can be responded from, for example, A/D converter having output states Pi , P2 , .... , P n as status of the information bits, as illustrated at status site la, or from other multiple monitorable conditions Ci , C2 , .... , C n , as illustrated at status site lb. It is understood that a system could readily be devised which functions both to monitor status of the monitorable conditions and to collect messages composed of the content/status of all information bits. So long as the status sites respond to a sequence of pulses applied to the conducting path, the status information or message responded to the conducting path can be received by a suitable monitoring stations/receiving status sites/message collectors and interpreted by either a human or machine. The pulse generator 4 and resistor Rg are necessary if the monitoring station such as 40b of FIG. 6 is used. INDUSTRIAL APPLICABILITY It can be seen that the invention provides systems of low cost and methods of simplicity in regard to the following applications: Supervision of the status of a plurality of dispersed/gathered sensors from one or more than one monitoring station, control of the status of a plurality of dispersed/gathered actuators from one or more than one monitoring station, supervision and control of the status of a plurality of dispersed/gathered sensors from one or more than one location, exchange of digital information between two or more than two message centers. The usefulness of the invention can be extremely enhanced by the application of superconductor.

Claims: CLAIMS 1. A system for retrieving status information from a plurality of status sites each comprises at least one monitorable condition, comprising: pulse generator means for generating a sequence of pulses; conducting path means for coupling said pulse generator means with said status sites; and means for determining, on said conducting path means, the appearing waveform of at least one of said pulses according to the status of one of said monitorable conditions which is associated with said at least one of said pulses, whereby the status of said one of said monitorable conditions can be recognized by observing, on said conducting path means, said appearing wave orm of said at least one of said pulses, whereby said status information of said monitorable condition at status sites can be retrieved on said conducting path means 2. The system of claim 1 wherein each said monitorable condition is assigned a predetermined integer and is associated with one of said pulses if said predetermined integer thereof corresponds to the sequence order of said one of said pulses. 3. The system of claim 1 wherein said one of said monitorable conditions is coupled to said conducting path means during the period of said at least one of said pulses, thereby said appearing waveform of said at least one of said pulses is determined according to the status of said one of said monitorable conditions. 4. The system of claim 3 further comprising a switching means for coupling said one of said monitorable conditions to said conducting path means. 5. The system of claim 1 wherein each said monitorable condition is assigned a predetermined integer and said system further comprises at least one monitoring station means for recognizing the status of said one of said monitorable conditions by observing said waveform of said at least one of said pulses which is associated with by said one of said monitorable conditions. 6. The system of claim 1 wherein when there is an opening fault with said conducting path means, the location of said opening fault can be estimated by recognizing the pulse of said sequence of pulses after which the remaining pulses of said sequence of pulses have waveforms not determined according to the status of said monitorable conditions. 7. A method for retrieving status information, through a conducting path, from a plurality of status sites each comprises at least one monitorable condition, comprising the steps of applying a sequence of pulses to said conducting path; determining, on said conducting path, the appearing waveform of at least one of said pulses according to the status of one of said monitorable conditions which is associated with said at least one of said pulses; observing said appearing waveform of said at least one of said pulses to recognize the status of said one of said monitorable conditions. 8. A system for transferring status information from a plurality of sending status sites each comprises at least one information bit, to a plurality of receiving status sites each comprises at least one memory bit, comprising: pulse generator means for generating a sequence of pulses; conducting path means for coupling said pulse generator means, said sending status sites, and said receiving status sites together; means for determining, on said conducting path means, the appearing waveform of at least one of said pulses according to the status of one of said information bits which is associated with said at least one of said pulses, and for determining the status of at least one of said memory bits according to said appearing waveform of said at least one of said pulses which is associated with said at least one of said memory bits, whereby the status of said one of said information bits is transferred to said at least one of said memory bits which is associated with by said at least one of said pulses. 9. The system of claim 8 wherein each said information bit and each said memory bit is assigned a predetermined integer, and wherein said one of said information bits is associated with said at least one of said pulses if said predetermined integer assigned thereto corresponds to the sequence order of said at least one of said pulses, and wherein said at least one of said pulses is associated with said at least one of said memory bits if the sequence order thereof corresponds to said predetermined integer assigned to said at least one of said memory bits. 10. A method for transferring status information, through a conducting path, from a plurality of sending status sites each comprises at least one information bit, to a plurality of receiving status sites each comprises at least one memory bit, comprising the steps of applying a sequence of pulses to said conducting path; determining, on said conducting path, the appearin waveform of at least one of said pulses according to the status of one of said information bits which is associated with said at least one of said pulses; determining the status of at least one of said memory bits according to said appearing waveform of said at least one of said pulses which is associated with said at least one of said memory bits, whereby the status of said one of said information bits is transferred to said at least one of said information bits is transferred to said at least one of said memory bits which is associated with by said at least one of said pulses.

Inventors: KUO TIN-MING, KUO, TIN-MING
Applicants: KIM NAOMI Y, KUO TIN MING, KIM, NAOMI, Y., KUO, TIN-MING
Application year: 1987
Main classification: G08B13
IPC codes: G08B25, H04Q9