Control and monitoring signal transmission system

Abstract

The present invention is provided with: a master station that transmits / receives data to / from a control unit; and a plurality of slave stations that transmit / receive data to / from the master station via a shared transmission line by using a transmission synchronization scheme. The transmission / reception of data between the master station and the slave stations is performed by superimposing data onto frames repeatedly transmitted from the master station. A transmission clock signal for synchronizing the master station and the slave stations is formed from a plurality of clock pulses. Each of the clock pulses has a data pulse used for data transmission between the master station and the slave stations. The data pulses are allocated to the respective slave stations. Each of the slave stations has a value set therefor as an address for allowing the slave station to obtain the timing of the data pulses allocated thereto. The data pulses are time-divided into a plurality of domains. At least one of the domains is defined as a changeable domain capable of being used for both data transmission from the master station and data transmission from the slave stations.

Description

[Technical Field]

[0001] The present invention relates to a control and monitoring signal transmission system that reduces the number of signal lines between a parent station on the controlling side and multiple child stations on the controlled side, connects them with a common transmission line, and transmits data using a transmission synchronization method such as synchronizing with a transmission clock.

[0002] In systems that centrally control a large number of devices installed within a facility, a reduction in the number of wires, or so-called wire-saving, is widely practiced. A commonly adopted method for reducing wires is to replace the parallel connection in which each of a plurality of devices installed on the controlled side is directly connected to a control unit installed on the controlling side by connecting a master station and a plurality of slave stations, each equipped with a function for converting parallel signals to serial signals, to the control unit and the plurality of devices, and to transmit and receive data between the master station and the plurality of slave stations via a common transmission line using serial signals.

[0003] Also, as a method for transmitting and receiving data by serial signals via a common transmission line, a transmission synchronization method is known in which data is synchronized by a transmission clock. A widely adopted method is to transmit and receive data between a master station and multiple slave stations by synchronizing them with a serial pulse signal (hereinafter referred to as a "transmission clock signal").

[0004] In a method of transmitting and receiving data synchronized by a transmission clock signal, frames repeatedly transmitted from a master station are time-divided, and a data area in which the direction of data transmission (from master station to slave station or from slave station to master station) is determined is assigned to each of the multiple slave stations, and data is superimposed on the data area. Furthermore, each slave station is assigned a numerical address to obtain the timing of its assigned data area, and each of the multiple slave stations transmits and receives data to and from the master station in its assigned data area, thereby preventing collisions between transmissions and receptions of the multiple slave stations.

[0005] An example of such data transmission is the control and monitoring signal transmission system proposed in Japanese Patent Laid-Open Publication No. 2002-152864. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-152864 Summary of the Invention [Problem to be solved by the invention]

[0007] In the conventional system in which a master station and a slave station synchronize with each other using a transmission clock signal to transmit and receive data, the number of clocks in the transmission clock signal is limited due to system configuration reasons, and the number of data areas (control data areas) used to transmit data from the master station to the slave station is set to the same as the number of data areas (monitoring data areas) used to transmit data from the slave station to the master station.

[0008] Therefore, if there is a difference between the number of control data areas and the number of monitoring data areas required for data exchange between a parent station and a child station, the number of clocks in the transmission clock signal becomes larger than necessary, which causes the frame to become redundant and reduces the response speed.

[0009] For example, if either the number of control data areas or the number of monitoring data areas required for data exchange between a parent station and a child station exceeds 128, the number of clocks in the transmission clock signal must be set to 256, and the response speed will be half that of when a transmission clock signal with a clock number of 128 is used.

[0010] Therefore, the present invention aims to provide a control and monitoring signal transmission system that can accommodate the number of control data areas and the number of monitoring data areas required for data exchange between a parent station and a child station without reducing response speed, without being restricted by the number of clocks of the transmission clock signal for synchronizing the parent station and the child station. [Means for solving the problem]

[0011] The control and monitoring signal transmission system according to the present invention includes a master station that exchanges data with a control unit, and multiple slave stations that exchange data with the master station via a common transmission line using a transmission synchronization method. Data is exchanged between the master station and the slave stations by superimposing data onto frames repeatedly transmitted from the master station. A transmission clock signal for synchronizing the master station and the slave stations is composed of multiple clock pulses, each of which has a data pulse used for data transmission between the master station and the slave stations. The data pulses are assigned to each of the slave stations, and a numeric value is set for each of the slave stations as an address for determining the timing of the data pulses assigned to that station. The data pulses are time-divided into multiple regions, and at least one of the regions is a changeable region that can be used for data transmission from both the master station and the slave stations.

[0012] A management data area that can be used by all of the slave stations may be provided in the frame, and the master station may use the management data area to transmit instruction data indicating either a first state in which the changeable area is used for data transmission from the master station or a second state in which the changeable area is used for data transmission from the slave station, and the slave stations may exchange data in accordance with the instruction data.

[0013] A management data area that can be used by all of the slave stations may be provided in the frame, and the master station may use the management data area to transmit instruction data indicating either a first state in which the changeable area is used for data transmission from the master station or a second state in which the changeable area is used for data transmission from the slave station, by specifying one of the addresses, and when the specified address matches its own station address, the slave station may exchange data in accordance with the instruction data.

[0014] A management data area that can be used by all of the slave stations may be provided in the frame, and the master station may use the management data area to transmit instruction data indicating either a first state in which the changeable area is used for data transmission from the master station or a second state in which the changeable area is used for data transmission from the slave station, by specifying one of the addresses, and when the specified address matches its own station address, the slave station may exchange data in accordance with the instruction data.

[0015] A management data area that can be used by all of the slave stations may be provided in the frame, the master station may use the management data area to specify the address, and collect information for each of the slave stations about data that the slave station receives from the master station and data that the slave station transmits to the master station, and based on the information, determine whether the changeable area of ​​each of the data pulses is in a first state used for data transmission from the master station or a second state used for data transmission from the slave station, and transmit instruction data indicating either the first state or the second state by specifying the address using the management data area, and when the specified address matches its own station address, the slave station may exchange data in accordance with the instruction data. [Effects of the Invention]

[0016] According to the present invention, the data pulses on which the data transmitted from the master station and the data transmitted from the slave station are superimposed are time-divided into a plurality of regions, and at least one of the regions is designated as a modifiable region that can be used for both data transmission from the master station and data transmission from the slave station. Therefore, if there is a difference in the number of control data regions and the number of monitoring data regions required for data transmission between the master station and the slave station, the modifiable region can be used as the region that is required more. Therefore, without being restricted by the number of clocks of the transmission clock signal, the number of control data regions and the number of monitoring data regions required for data transmission between the master station and the slave station can be accommodated without a decrease in response speed. [Brief explanation of the drawings]

[0017] [Figure 1] 1A and 1B show the transmission procedure of a transmission signal in an embodiment of the control and monitoring signal transmission system of the present invention, in which (a) is a schematic diagram when the entire changeable area is used for data transmission from a slave station, (b) is a schematic diagram when the entire changeable area is used for data transmission from a master station, and (c) is a schematic diagram when part of the changeable area is used for data transmission from the master station and the other part is used for data transmission from a slave station. [Figure 2] FIG. 2 is a system configuration diagram of the embodiment. [Figure 3] FIG. 2 is a functional block diagram of a master station. [Figure 4] FIG. 2 is a time chart of a transmission signal. [Figure 5] FIG. 2 is a functional block diagram of an input slave station. [Figure 6] FIG. 2 is a functional block diagram of an output slave station. [Figure 7] 10 is a time chart of a transmission signal in another embodiment of the control and monitoring signal transmission system according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] An embodiment of a control and monitoring signal transmission system according to the present invention will be described. This control and monitoring signal transmission system is intended for centralized control of a large number of devices and equipment located in a facility such as a factory using a control unit. As shown in Figure 2, it is composed of a control unit 1, a master station 2 connected to common data signal lines DP and DN (hereinafter referred to as transmission lines), and multiple input slave stations 4, output slave stations 5, and input / output slave stations 6 located in the facility to be controlled and connected to the transmission lines. The type and number of slave stations connected to the transmission lines can be determined appropriately depending on the state in which the system is used, etc. Also, for convenience of illustration, Figure 2 does not show all of the slave stations that make up the system.

[0019] The input unit 7 to which the input slave station 4 is connected, the output unit 8 to which the output slave station 5 is connected, and the input / output unit 9 to which the input / output slave station 6 is connected are devices located within the facility to be controlled.

[0020] Examples of the input unit 7 include, but are not limited to, a reed switch, a microswitch, a push button switch, a photoelectric switch, and various other sensors.

[0021] Examples of the output unit 8 include, but are not limited to, an actuator, a (stepping) motor, a solenoid, a solenoid valve, a relay, a thyristor, and a lamp.

[0022] The input / output unit 9 is a device that has the functions of both the input unit 7 and the output unit 8. For example, a device such as a temperature controller, timer, or counter can be used that has both the function of transmitting information to the master station 2 and the function of performing an output operation based on data transmitted from the master station 2.

[0023] The input unit 7 may be an input unit-integrated slave station 70 integrated with the input slave station 4. The output unit 8 may be an output unit-integrated slave station 80 integrated with the output slave station 5.

[0024] The control unit 1 includes a management and judgment means 11 having a calculation function and an input / output unit 12. The management and judgment means 11 receives data from the master station 2 via the input / output unit 12 and performs necessary calculations based on a program stored inside.

[0025] <Configuration of the master station> 3, the master station 2 is equipped with an output data section 21, a management data section 22, a timing generation section 23, a master station output section 24, a master station input section 25, and an input data section 26. The master station 2 superimposes control data on a voltage clock signal having a predetermined period and duty ratio and transmits the superimposed control data, and also extracts monitoring data transmitted from the input slave station 4, the output slave station 5, and the input / output slave station 6 (hereinafter, these may be collectively referred to as "slave stations 4, 5, 6") and outputs the data to the input / output unit 12 of the control section 1.

[0026] The output data unit 21 transfers the data received from the control unit 1 to the parent station output unit 24 as serial data.

[0027] Based on the data received from the control unit 1, the management data unit 22 transfers data required for issuing instructions to the slave stations in a management control data area (to be described later) to the master station output unit 24 as serial data.

[0028] The timing generating unit 23 comprises an oscillator circuit (OSC) 31 and timing generating means 32. Based on the oscillator circuit (OSC) 31, the timing generating means 32 generates a timing clock for this system and passes it to the parent station output unit 24 and parent station input unit 25.

[0029] The parent station output unit 24 comprises a control data generating means 33 and a line driver 34. Based on the data received from the output data unit 21 and the timing clock received from the timing generating unit 23, the control data generating means 33 transmits a transmission signal in which control data is superimposed on a transmission clock signal via the line driver 34.

[0030] In this embodiment, a voltage clock signal that transmits a timing clock using voltage changes is used as the transmission clock signal, but there is no limitation on the method of transmitting the timing clock, and other methods suitable for the usage situation may be used.

[0031] The voltage clock signal is composed of multiple clock pulses. Each clock pulse has a period (hereinafter referred to as a "high period") during which the voltage level Ep is higher than the threshold value Est, as in the transmission signal shown in Figure 4. In this embodiment, the voltage level Ep is set to +24V.

[0032] The high period functions as a synchronous clock and a power supply voltage for communication, but the width and voltage level are not limited to those in this embodiment as long as they satisfy these requirements. They can be determined appropriately depending on the usage environment and usage state. For example, a negative voltage lower than the ground level may be maintained for a predetermined period of time.

[0033] Each clock pulse also has a data pulse which is used for data transmission between the master station 2 and the slave stations 4, 5, and 6.

[0034] In this embodiment, the data value of each data pulse is represented by a voltage level. However, the voltage level representing the data value can be determined appropriately depending on the usage environment and usage state. For example, it may be a negative voltage lower than the ground level.

[0035] Each data pulse is time-divided into four regions. In the following explanation, the four regions in the data pulse are referred to as the V region, i region, f region, and P region in order of decreasing order from the point where the voltage level drops from the voltage level Ep of the high period.

[0036] The V region in this embodiment corresponds to the changeable region of the present invention, and can be used for data transmission from both the master station 2 and the slave stations 4, 5, and 6. In this embodiment, the i and f regions are used only for data transmission from the slave stations 4, 5, and 6, and the P region is used only for data transmission from the master station 2.

[0037] The V region, i region, f region, and P region can be used according to the situation. Specifically, any of the V region, i region, f region, and P region may be used as the variable region, and any of the regions may be used for data transmission from the slave station and data transmission from the master station. Furthermore, multiple variable regions may be provided. However, in this embodiment, it is preferable that the P region, which includes the rising edge of the high period, be used in a manner that extends the high period, taking into account its function as a synchronous clock during the high period and as a power supply voltage for communication.

[0038] In this embodiment, in any of the V region, i region, and f region, a potential VL lower than the threshold Ect is a voltage level indicating a logical data value of "1." Also, a potential VM higher than the threshold Ect is a voltage level indicating a logical data value of "0." In this embodiment, the threshold Ect is set between 10 V and ground level (approximately 6 V), but there is no limit to its magnitude and it may be set according to the usage situation and environment. There is also no limit to the correspondence between the voltage level indicating the data value and the logical data value and it can be determined appropriately according to the usage environment and state.

[0039] In this embodiment, in the P region, a potential lower than the threshold value Est is a voltage level indicating a logical data value of "1." Furthermore, a potential higher than the threshold value Est is a voltage level indicating a logical data value of "0." As with the V region, i region, and f region, there are no restrictions on the correspondence between the voltage level indicating the data value and the logical data value, and this can be determined appropriately depending on the usage environment and usage state.

[0040] The voltage clock signal is transmitted repeatedly from the master station 2, with one frame consisting of a series of high periods with a predetermined number of periods. As shown in Figure 1, one frame contains a management data area and a control and monitoring data area.

[0041] At the beginning of each frame, a start signal ST is transmitted, the high period of which voltage level Ep is maintained for a longer period than the high period, and this separates each frame. There is no limit to the length of the start signal ST, as long as it can be distinguished from the high period, and it can be determined appropriately taking into account the conditions of use, etc.

[0042] A predetermined area within the control and monitoring data area is allocated to each of the slave stations 4, 5, and 6. Control data from the master station 2 to the output slave station 5 and input / output slave station 6 is superimposed on the area allocated to the target slave station, and monitoring data from the input slave station 4 and input / output slave station 6 to the master station 2 is superimposed on the area allocated to the slave station that transmits the monitoring data. In this way, the control and monitoring data area is used for sending and receiving regular data between the master station 2 and the slave stations 4, 5, and 6.

[0043] The management data area is used to transmit and receive non-stationary data that cannot be transmitted and received using the control and monitoring data area. The instruction data of the present invention is transmitted using this management data area, and the transmission procedure will be described in detail later.

[0044] The master station input unit 25 comprises a line receiver 35 and a monitoring data extraction means 36. The line receiver 35 receives a transmission signal from the transmission line, shapes the waveform, and passes it to the monitoring data extraction means 36.

[0045] The monitoring data extraction means 36 obtains the timing for extracting the data value using the timing clock delivered from the timing generation unit 23, and extracts data based on the digital value of the voltage level of the voltage clock signal delivered from the line receiver 35. Then, it delivers the steady-state data DIO superimposed on the control / monitoring data area and the management data DEX superimposed on the management data area to the input data unit 26.

[0046] The input data section 26 converts the serial input data received from the monitoring data extraction means 36 into parallel data, and outputs it to the input / output unit 12 of the control section 1 as monitoring data and management monitoring data.

[0047] <Configuration of input slave station> As shown in FIG. 5, the input slave station 4 includes a slave station input unit 40 that performs the main arithmetic processing, and a slave station line receiver 48 and a slave station line driver 49 that are arranged between the slave station input unit 40 and the transmission line. The input slave station 4 receives a voltage clock signal from the transmission line via the slave station line receiver 48 and transmits monitoring data via the slave station line driver 49.

[0048] The slave station input unit 40 includes a transmission / reception means 41 , a management control data extraction means 42 , an address extraction means 43 , an address setting means 44 , a management monitoring data transmission means 45 , an input means 46 , a monitoring data transmission means 47 , and a changeable area validation means 61 .

[0049] The input slave station 4 of this embodiment includes an MCU, which is a microcomputer control unit, as an internal circuit, and this MCU functions as the slave station input section 40.

[0050] The slave station line receiver 48 receives the transmission signal from the transmission line, shapes the waveform, and passes it to the transmission / reception means 41 .

[0051] The transmission / reception means 41 discriminates between the voltage level thresholds Est and Ect, and passes the digital value of the voltage level of the transmission signal handed over from the slave station line receiver 48 to the management control data extraction means 42, address extraction means 43, and management monitoring data transmission means 45.

[0052] The management control data extraction means 42 identifies the start signal ST based on the digital value of the voltage level of the transmission signal. Then, starting from the timing when the start signal ST ends (falling in this embodiment), management data is extracted based on the digital value of the voltage level of the data IO area in the management data area. This is then handed over to processing means for executing processing based on the management data. Note that FIG. 6 shows the modifiable area validation means 61 as processing means when instruction data is used as management data, but other processing means are not shown.

[0053] The address extraction means 43 identifies the start signal ST based on the digital value of the voltage level of the transmission signal, and counts the high period starting from the timing when the start signal ST ends (in this embodiment, the falling edge).Then, it obtains the timing when this count value matches the local station address data set by the address setting means 44. Note that this timing is the timing when the area assigned to the local station (hereinafter referred to as the "local station area") in the control and monitoring data area starts (hereinafter referred to as the "local station area start timing").

[0054] The address extraction means 43 also obtains the timing of the V region, i region, and f region based on the elapsed time from the falling edge of the high period.

[0055] Then, upon obtaining the local station area start timing, the address extraction means 43 activates the monitoring data transmission means 47 during the period of the i area and f area assigned to the local station, and during the period of the V area if a signal indicating activation of the V area is output by the modifiable area activation means 61. Note that if the local station area is made up of a plurality of data pulses, the monitoring data transmission means 47 is activated each time the i area and f area assigned to the local station and the activated V area appear, until the local station area ends.

[0056] The management and monitoring data transmission means 45 determines the start signal ST based on the digital value of the voltage level of the transmission signal, and outputs monitoring data as needed in the management data area starting from the timing when the start signal ST ends.

[0057] The monitoring data transmitted from the management monitoring data transmitting means 45 is transmitted only when the data to be transmitted to the master station 2 has been handed over from the processing means for executing processing based on the management data.

[0058] The input means 46 transfers data based on the input from the input unit 7 to the monitoring data transmission means 47 .

[0059] When the monitoring data transmitting means 47 is validated by the address extracting means 43, it transmits the data passed from the input means 46 via the slave station line driver 49 as monitoring data.

[0060] When instruction data is handed over from the management control data extraction means 42, if the instruction data indicates the second state (a state in which the alterable area is used for data transmission from the slave stations 4, 5, and 6), the alterable area validation means 61 outputs a signal indicating the validation of the V area to the address extraction means 43.

[0061] <Output slave station configuration> As shown in Fig. 6, the output slave station 5 includes a slave station output unit 50 that performs the main arithmetic processing, and a slave station line receiver 48 and a slave station line driver 49 that are arranged between the slave station output unit 50 and the transmission line. The output slave station 5 receives a transmission signal from the transmission line via the slave station line receiver 48, outputs information based on control data to the output unit 8, and operates or stops the output unit 8. When data transmission using the management data area is required, monitoring data is transmitted via the slave station line driver 49. In Fig. 6, parts that are substantially the same as those in the input slave station 4 are designated by the same reference numerals, and their description will be simplified or omitted.

[0062] The slave station output unit 50 includes a transmission / reception means 41 , a management control data extraction means 42 , an address extraction means 43 , an address setting means 44 , a management monitoring data transmission means 45 , a control data extraction means 51 , an output means 52 , and a changeable area validation means 61 .

[0063] Like the input slave station 4, the output slave station 5 of this embodiment also has an MCU, which is a microcomputer control unit, as an internal circuit, and this MCU functions as a slave station output section 50.

[0064] The transmission and reception means 41 of the output slave station 5 passes the digital value of the voltage level of the transmission signal passed from the slave station line receiver 48 to the management control data extraction means 42, address extraction means 43, management monitoring data transmission means 45, and control data extraction means 51.

[0065] The address extraction means 43 of the output slave station 5 obtains the local station area start timing and the timings of the V area and P area. Then, having obtained the local station area start timing, the address extraction means 43 activates the control data extraction means 51 during the period of the P area assigned to the local station, and during the period of the V area if the modifiable area activation means 61 outputs a signal indicating activation of the V area. Note that if the local station area is made up of multiple data pulses, the control data extraction means 51 is activated each time the P area assigned to the local station and the activated V area appear, until the local station area ends.

[0066] When the control data extraction means 51 is enabled by the address extraction means 43 , it extracts control data based on the digital value of the voltage level of the transmission signal delivered from the transmission / reception means 41 and delivers it to the output means 52 .

[0067] The output means 52 outputs information based on the control data passed from the control data extraction means 51 to the output unit 8, and activates or stops the output unit 8.

[0068] When instruction data is handed over from the management control data extraction means 42, the modifiable area validation means 61 of the output slave station 5 outputs a signal indicating the validation of the V area to the address extraction means 43 if the instruction data indicates the first state (a state in which the modifiable area is used for data transmission from the master station 2).

[0069] <Configuration of input / output slave stations> The input / output slave station 6 has the functions of both the input slave station 4 and the output slave station 5, and has a slave station input / output section that combines the configuration of both the slave station input section 40 and the slave station output section 50. However, since its configuration is essentially the same as the slave station input section 40 and the slave station output section 50, illustration and description thereof will be omitted.

[0070] <Procedure for sending instruction data> The procedure for transmitting instruction data will be described with reference to FIG. As shown in Figure 1(a), when the entire changeable area of ​​the control and monitoring data area is used for data transmission from the input slave station 4 and the input / output slave station 6, the master station 2 uses the management data area for each frame to transmit instruction data indicating the second state to all of the slave stations 4, 5, and 6. The input slave station 4 and the input / output slave station 6 that receive the instruction data use the changeable V area for transmission from their own stations.

[0071] As shown in Figure 1(b), when the entire modifiable area of ​​the control and monitoring data area is used for data transmission from parent station 2, parent station 2 uses the management data area to transmit instruction data indicating the first state to all of child stations 4, 5, and 6 for each frame. Upon receiving the instruction data, output child station 5 and input / output child station 6 extract the data in the V area as control data from parent station 2.

[0072] As shown in FIG. 1(c), part of the modifiable area of ​​the control and monitoring data area can be used for data transmission from the master station 2, and the other part can be used for data transmission from the input slave station 4 and the input / output slave station 6. In this case, the modifiable area validation means 61 of the slave stations 4, 5, and 6 has a function for storing instruction data. Then, at a predetermined timing, such as when the system is started, the master station 2 uses the management data area to send instruction data indicating a first state to each of the output slave stations 5 by specifying an address, and to send instruction data indicating a second state to each of the input slave stations 4 by specifying an address. For the input / output slave stations 6, either instruction data indicating the first state or instruction data indicating the second state is sent by specifying the address of the corresponding input / output slave station 6, depending on the required usage.

[0073] When the specified address matches the address of the input slave stations 4, 5, and 6, they receive and store the instruction data, and the input slave station 4 uses the V area for transmission from the input slave station, and the output slave station 5 extracts the data in the V area as control data from the master station 2. In addition, the input / output slave station 6 corresponds to the instruction data and uses the V area for transmission from the input slave station, or extracts the data in the V area as control data from the master station 2.

[0074] The state of the changeable area, i.e., whether it is the first state or the second state, is determined based on the number of control data areas and the number of monitoring data areas required for data exchange between the master station 2 and the slave stations 4, 5, and 6. The number of control data areas and the number of monitoring data areas required are determined at the system design stage, but the system configuration may be changed depending on the equipment in consideration of usage conditions. In such cases, it is preferable to determine the state of the changeable area based on the current system configuration.

[0075] In this embodiment, it is assumed that the master station 2 uses the management data area to specify an address for each of the slave stations 4, 5, and 6, and collects information about the data received from the master station 2 and the data transmitted to the master station 2 for each of the slave stations 4, 5, and 6. Then, based on the collected information, it is possible to determine whether the changeable range of each data pulse is in the first state or the second state.

[0076] In this embodiment, data values ​​in the V, i, f, and P regions are extracted based on voltage levels detected at predetermined times within the regions. That is, data is exchanged by associating the voltage levels of the transmission signals with data values. However, in the P region, which includes the rising edge of the HIGH period, data may be exchanged by associating the rising edge of the HIGH period with the data value.

[0077] 7 is a timing chart of a transmission signal in an embodiment in which data is exchanged by making the rising timing of the high period correspond to the data value in the P region. In the description of the embodiment shown in FIG. 7, parts that are substantially the same as those in the embodiments shown in FIGS. 1 to 6 are given the same reference numerals, and their description will be omitted or simplified.

[0078] 7, the rising timing of the high period in the P region corresponds to the data value. The rising timing of the high period in the P region can be obtained by measuring the elapsed time from the falling edge to the rising edge of the high period.

[0079] 7, an elapsed time TL longer than a predetermined threshold indicates a data value of "1" corresponding to a small time width, and an elapsed time TS shorter than the predetermined threshold indicates a data value of "0" corresponding to a large time width. There are no restrictions on the correspondence between the rising timing of the high period and the data value, and it can be set appropriately depending on the usage situation. [Explanation of symbols]

[0080] 1. Control section 2 Master station 4 Input slave station 5 Output slave station 6 Input / output slave stations 7 Input section 8 Output section 9 Input / output section 11 Management Judgment Means 12 Input / Output Unit 21 Output data section 22 Management Data Section 23 Timing generator 24 Master station output section 25 Master station input section 26 Input data section 31 Oscillator circuit (OSC) 32 Timing generation means 33 Control data generating means 34 Line Driver 35 Line Receiver 36 Monitoring data extraction methods 40 Slave station input section 41 Transmission and reception means 42 Management Control Data Extraction Methods 43 Address Extraction Method 44 Address setting method 45 Management and monitoring data transmission means 46 Input Methods 47 Monitoring data transmission means 48 Slave station line receiver 49 Slave station line driver 50 Slave station output section 51 Control data extraction means 52 Output Method 61 Modifiable area activation means 70 Input unit integrated slave station 80 Output unit integrated slave station

Claims

1. a master station that transmits and receives data to and from a control unit, and a plurality of slave stations that transmit and receive data to and from the master station by a transmission synchronization method via a common transmission line; data is exchanged between the master station and the slave station by superimposing data on frames repeatedly transmitted from the master station; a transmission clock signal for synchronizing the master station and the slave station is composed of a plurality of clock pulses, each of the clock pulses having a data pulse used for data transmission between the master station and the slave station; the data pulses are assigned to each of the slave stations; A numerical value is set for each of the slave stations as an address for the slave station to obtain the timing of the data pulse assigned to that station, A control and monitoring signal transmission system characterized in that the data pulse is time-divided into a plurality of regions, and at least one of the regions is a changeable region that can be used for data transmission from either the parent station or the child station.

2. 2. The control and monitoring signal transmission system of claim 1, wherein a management data area that can be used by all of the slave stations is provided in the frame, and the master station uses the management data area to transmit instruction data indicating either a first state in which the changeable area is used for data transmission from the master station or a second state in which the changeable area is used for data transmission from the slave station, and the slave stations exchange data in accordance with the instruction data.

3. 2. A control and monitoring signal transmission system according to claim 1, wherein a management data area that can be used by all of the slave stations is provided in the frame, and the master station transmits instruction data indicating either a first state in which the changeable area is used for data transmission from the master station or a second state in which the changeable area is used for data transmission from the slave station by specifying one of the addresses using the management data area, and when the specified address matches its own station address, the slave station exchanges data in accordance with the instruction data.

4. 2. The control and supervisory signal transmission system according to claim 1, wherein a management data area that can be used by all of the slave stations is provided in the frame, the master station uses the management data area to specify the address, and collects, for each of the slave stations, information on data that the slave station receives from the master station and data that the slave station transmits to the master station, and determines, based on the information, for the changeable area of ​​each of the data pulses, either a first state used for data transmission from the master station or a second state used for data transmission from the slave station, and transmits instruction data indicating either the first state or the second state by specifying the address using the management data area, and when the specified address matches its own station address, the slave station exchanges data in accordance with the instruction data.

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