Control / monitoring signal transmission system

Abstract

The present invention is provided with a check data transmission node (3) that converts all of monitoring data, which is transmitted from a plurality of transmission nodes (4, 6) to a reception node (2) via common transmission lines (DP, DN), into check data using a predetermined conversion rule, and transmits the check data to the transmission nodes. The transmission nodes convert all of the monitoring data into collation data using the conversion rule, and if the check data and the collation data do not match, output data to an error detection area shared by all of the transmission nodes. One of the transmission nodes or the reception node may also serve as the check data transmission node.

Description

Control and monitoring signal transmission system

[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 reduction, is widely practiced. A common 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 with a master station and a plurality of slave stations each equipped with a parallel-to-serial signal conversion function, which are connected to the control unit and the plurality of devices, and data is exchanged between the master station and the plurality of slave stations via a common transmission line using serial signals. Furthermore, a transmission synchronization method, such as synchronization using a transmission clock, is often used as a method for exchanging data via a common transmission line using serial signals.

[0003] However, when wiring reduction is realized, if a large number of slave stations are connected and the control unit is unable to identify errors in the transmission data at the slave stations, it will be necessary to check each of the slave stations that are far away from the control unit, which will require a lot of labor to detect errors in the transmission data at the slave stations.

[0004] Therefore, the present applicant has proposed a control and monitoring signal transmission system disclosed in Patent Publication No. 5738498 as a system in which the parent station can check whether or not there are errors in the transmission data in a transmission synchronization method without reducing the transmission speed of the transmission data.

[0005] In the above system, a management data area, separate from the control / monitoring data area, is provided in the transmission procedure and is composed of transmission control data for multiple slave stations and transmission monitoring data superimposed from multiple slave stations. The master station designates any slave station via the management data area, and the designated slave station transmits to the master station either control transmission check data, obtained by extracting all of the transmission control data and converting it according to a predetermined rule, or monitoring transmission check data, obtained by extracting all of the transmission monitoring data and converting it according to a predetermined rule. The master station then compares the control transmission check data, converted based on all of the transmission control data using the same rules as the slave station, with the monitoring transmission check data, converted based on all of the transmission monitoring data using the same rules as the slave station, to check for errors in the transmission data.

[0006] That is, at the data sender (the sender of control data is the parent station, and the sender of monitoring data is the child station, hereafter referred to as the "sending node") and the data receiver (the sender of control data is the child station, and the sender of monitoring data is the parent station and child stations other than the parent station, hereafter referred to as the "receiving node"), the presence or absence of a transmission error in the data sent from the parent station is confirmed by comparing the transmitted data with data based on the data sent from the parent station and data based only on the transmitted data.

[0007] Patent No. 5738498

[0008] However, in conventional systems in which the transmitting node and the receiving node compare the transmitted data with data based on data sent from the node itself and data based only on the transmitted data to check for transmission errors, as the number of transmitting nodes increases, the number of transmission procedures for checking for transmission errors at each transmitting node increases, and it may not be possible to obtain the required transmission speed.

[0009] Therefore, an object of the present invention is to provide a control and monitoring signal transmission system that can check for transmission errors by comparing transmitted data, data based on data sent from the own station, and data based only on transmitted data, without increasing the number of transmission procedures, even when the number of transmitting nodes is large.

[0010] The control / monitoring signal transmission system of the present invention includes a check data transmitting node that converts all of the monitoring data transmitted from multiple transmitting nodes to a receiving node via a common transmission line into check data using a predetermined conversion rule and transmits the check data to the transmitting node, and the transmitting node converts all of the monitoring data into comparison data using the conversion rule, and if the check data and the comparison data do not match, outputs the data to an NG detection area shared by all of the transmitting nodes.

[0011] One of the transmitting nodes or the receiving node may also serve as the check data transmitting node.

[0012] The plurality of transmitting nodes and the receiving node exchange data via the common transmission line using a transmission synchronization method, and the data output to the NG detection area is binary data that is either first data indicating that there is a transmission error or second data indicating that there is no transmission error, and if the check data and the comparison data do not match, the transmitting node outputs the first data to the NG detection area, and the data value of the NG detection area after the first data is output may be maintained at the first data.

[0013] Data exchange between the multiple transmitting nodes and the receiving node is performed by superimposing data onto frames that are repeatedly transmitted from the receiving node, and the frames may be time-divided, and a control / monitoring data area in which the direction of data transmission is determined and assigned to each of the transmitting nodes, and a management data area separate from the control / monitoring data area may be provided for use in exchanging data with all of the transmitting nodes.

[0014] The check data may be a CRC.

[0015] According to the present invention, the transmitting node compares the check data transmitted from the check data transmitting node with the comparison data obtained by the transmitting node, and if the check data and the comparison data do not match, the transmitting node outputs the data to an NG detection area shared by all of the transmitting nodes, making it possible to check for the presence or absence of a transmission error based on the presence or absence of data output in the NG detection area. In other words, even if the number of transmitting nodes increases, it is possible to check for the presence or absence of a transmission error by comparing the transmitted data, data based on the data transmitted from the transmitting node, and data based only on the transmitted data, without increasing the transmission procedure.

[0016] It is a system configuration diagram of an embodiment of the control and monitoring signal transmission system according to the present invention. It is a functional block diagram of a master station. It is a time chart diagram of a transmission signal. It is a schematic diagram showing a transmission procedure of a transmission signal. It is a functional block diagram of an input slave station. It is a functional block diagram of an output slave station. It is a functional block diagram of a terminator in another embodiment of the control and monitoring signal transmission system according to the present invention.

[0017] 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 designed to centrally control a large number of devices and equipment installed in a facility such as a factory using a control unit. As shown in Fig. 1, the system comprises a master station 2 connected to a control unit 1 and common data signal lines DP and DN (hereinafter referred to as transmission lines), a plurality of input slave stations 4, output slave stations 5, and input / output slave stations 6 installed in the facility to be controlled and connected to the transmission lines, and a terminator 3 connected to the transmission lines. Note that, for convenience of illustration, Fig. 1 shows only one of each slave station, but there is no limit to the type or number of slave stations that can be connected to the transmission lines.

[0018] The terminator 3 properly maintains the voltage level of the potential VM higher than the threshold Ect, which indicates a predetermined logical data value in the data IO area, as described below, thereby suppressing the occurrence of errors due to fluctuations in the voltage level of the transmission line.

[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, 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 determination means 11 having a calculation function and an input / output unit 12. The management and determination means 11 receives data from the master station 2 via the input / output unit 12, and performs necessary calculations based on a program stored therein.

[0025] <Configuration of Master Station> The master station 2 is connected to the transmission line and, as shown in Fig. 2, comprises 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, an input data section 26, and a data error determination section 27. 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 extracts monitoring data transmitted from the input slave station 4, the output slave station 5, and the input / output slave station 6, and outputs the data to the input / output unit 12 of the control unit 1. Furthermore, the master station 2 determines whether or not an error exists in the transmitted data based on whether or not data is output in the NG detection area, and outputs the result to the input / output unit 12 of the control unit 1.

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

[0027] The management data unit 22 transfers data required for issuing instructions to the slave stations in a management data area (described later) as serial data to the parent station output unit 24 based on the data received from the control unit 1. The management data unit 22 also executes a monitoring transmission check conversion to convert all of the monitoring data transmitted from the multiple input slave stations 4 and input / output slave stations 6 into check data according to predetermined rules, and transfers the obtained check data to the parent station output unit 24.

[0028] The timing generating unit 23 comprises an oscillator circuit (OSC) 31 and timing generating means 32 , and 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 voltage clock signal on which control data is superimposed to the transmission line via the line driver 34.

[0030] 3, the voltage clock signal is composed of a series of clock voltage regions in which a voltage level Ep higher than a threshold value Est is maintained for a predetermined time, with a fixed period. In this embodiment, the voltage level Ep is set to +24 V.

[0031] The clock voltage range is not limited as long as it functions as a synchronous clock, and can be determined appropriately depending on the environment and state of use. For example, it may be a range in which a negative voltage lower than the ground level is maintained for a predetermined period of time.

[0032] In the region between the clock voltage regions (hereinafter referred to as the "data IO region"), data values ​​are represented by voltage levels lower than the voltage level Ep.

[0033] In this embodiment, a potential VL (second potential) lower than the threshold Ect is a voltage level indicating a logical data value of "1," and a potential VM (first potential) higher than the threshold Ect is a voltage level indicating a logical data value of "0." However, the voltage level indicating the data value can be determined appropriately depending on the usage environment and usage state, as long as it can be distinguished from the clock voltage. It may also be a voltage level higher than the voltage level Ep of the clock voltage region. The same applies when the voltage level Ep of the clock voltage period is a negative voltage lower than the ground level.

[0034] In this embodiment, the threshold value Ect is set between 10 V and the ground level (approximately 6 V), but there is no limit to the magnitude and it may be set according to the usage situation and environment. Furthermore, there is no limit to the correspondence between the voltage level indicating the data value and the logical data value and it may be determined appropriately according to the usage environment and the usage state.

[0035] In the data IO area, the data value is also indicated by the duration of the data IO area. In this embodiment, if one period of the voltage clock signal is defined as t0 from the rising edge of the clock voltage area to the rising edge of the next clock voltage area, then the time (3 / 4)t0 in the data IO area indicates logical data "0," and the time (1 / 4)t0 indicates logical data "1." There is no limit to the length of these times, and they can be determined appropriately as long as they correspond to the value of the control data input from the control unit 1. However, from the viewpoint of clock function stability, a high duty ratio is preferable.

[0036] The voltage clock signal is repeatedly transmitted from the master station 2, with one frame consisting of a series of clock voltage areas of a predetermined length. As shown in Fig. 4, one frame contains a first management data area, a control and monitoring data area, and a second management data area.

[0037] At the beginning of each frame, a start signal ST is transmitted, in which the voltage level Ep of the clock voltage domain is maintained for a longer time than the clock voltage domain, thereby separating each frame. There is no limit to the length of the start signal ST, as long as it can be distinguished from the clock voltage domain, and it can be determined appropriately taking into account the conditions of use, etc.

[0038] A predetermined area within the control and monitoring data area is allocated to each of the input slave station 4, output slave station 5, and input / output slave station 6 (hereinafter, these may be collectively referred to as "slave stations 4, 5, 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, or 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. As a result, 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, 6.

[0039] The first management data area is used for transmitting and receiving non-stationary data that cannot be transmitted and received using the control and monitoring data area.

[0040] The second management data area is made up of a check data output area (represented as a "CRC area" in FIG. 4) and an NG detection area.

[0041] The check data output area is superimposed with check data transmitted from the parent station 2 to the child stations 4, 5, and 6. In this embodiment, a CRC is used as the check data, and therefore, in the following description, the check data output area will be referred to as the "CRC area." Note that the check data is not limited to a CRC, and other known frame check sequences may be used depending on the usage situation, etc. However, a CRC has the advantage that it can perform calculations faster than a Hamming code in the same device configuration, and furthermore, it can detect burst errors caused by transient, strong noise due to the ON / OFF switching of relays or motors, which are difficult to detect using parity.

[0042] Data is output to the NG detection area from slave stations 4, 5, and 6 where, as a result of comparing the check data with the verification data described below, the check data and the verification data do not match. In this embodiment, when the check data and the verification data do not match, a logical data value of "1" is output as data (first data) indicating the presence of a transmission error, and this value is maintained. Note that the data output to the NG detection area may be binary data that is either the first data indicating the presence of a transmission error or the second data indicating the absence of a transmission error, and a logical data value of "0" may also be output as the first data.

[0043] The parent station input unit 25 is made up of a line receiver 35 and a monitoring data extraction means 36. The line receiver 35 receives a voltage clock signal from the transmission line, shapes the waveform, and passes it to the monitoring data extraction means 36.

[0044] The monitoring data extraction means 36 obtains the timing for extracting data values ​​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, which is monitoring data superimposed on the control / monitoring data area, to the management data unit 22 and the input data unit 26. It also delivers the management data DEX superimposed on the first management data area to the input data unit 26. It also delivers the data DNG in the NG detection area to the transmission error determination unit 27.

[0045] 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.

[0046] The transmission error determination unit 27 determines whether or not there is an error in the transmission data based on the data DNG in the NG detection area received from the monitoring data extraction means 36. In this embodiment, if the data DNG in the NG detection area has a logical data value of "1," it determines that a transmission error has occurred. Then, as a determination result, data indicating that there is an error in the transmission data is output to the input / output unit 12 of the control unit 1.

[0047] <Configuration of Input Slave Station> As shown in FIG. 5, the input slave station 4 includes a slave station input unit 40 that executes 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 receiving means 41 , a management control data extracting means 42 , an address extracting means 43 , an address setting means 44 , a management monitoring data transmitting means 45 , an input means 46 , a monitoring data transmitting means 47 and a transmission error detecting means 53 .

[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 a slave station input section 40 .

[0050] The slave station line receiver 48 receives the voltage clock 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 voltage clock 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 transmission error detection means 53.

[0052] The management control data extraction means 42 identifies the start signal ST based on the digital value of the voltage level of the voltage clock signal. Then, starting from the timing when the start signal ST ends (in this embodiment, the falling edge), it extracts management data based on the value of the data IO area in the first management data area. The extracted management data is passed to processing means (not shown) for executing processing based on the data.

[0053] The management control data extraction means 42 also counts the clock voltage field starting from the timing when the start signal ST ends (in this embodiment, the falling edge) to obtain the timing of the second management data field, and then extracts the value of the CRC field as check data and passes it to the transmission error detection means 53.

[0054] The address extraction means 43 identifies the start signal ST based on the digital value of the voltage level of the voltage clock signal, and counts the clock voltage region starting from the timing when the start signal ST ends (in this embodiment, the falling edge).Then, it obtains the timing at which this count value matches the local station address data set by the address setting means 44. Note that this timing is the timing at which the region assigned to the local station (hereinafter referred to as the "local station region") in the control and monitoring data region starts (hereinafter referred to as the "local station region start timing").

[0055] Then, upon obtaining the local station area start timing, the address extraction means 43 activates the monitoring data transmission means 47. Furthermore, if the local station area includes multiple data IO areas, the monitoring data transmission means 47 is activated in the data IO area every time a data IO area appears until the local station area ends.

[0056] The management / monitoring data transmitting means 45 determines the start signal ST based on the digital value of the voltage level of the voltage clock signal. Then, starting from the timing when the start signal ST ends, it outputs monitoring data in the first management data area as needed. However, the monitoring data transmitted from the management / monitoring data transmitting means 45 using the first management data area is transmitted only when data to be transmitted to the parent station 2 has been handed over from a processing means (not shown).

[0057] The management / monitoring data transmitting means 45 also counts the clock voltage region starting from the timing when the start signal ST ends (in this embodiment, the falling edge) to obtain the timing of the NG detection region. Then, if the transmission error detecting means 53 has delivered a logical data value of "1" to be output when the check data and the verification data do not match, the management / monitoring data transmitting means 45 outputs this value.

[0058] The input means 46 passes data based on the input from the input unit 7 to the monitored data transmitting means 47 and the transmission error detecting means 53 .

[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 as monitoring data via the slave station line driver 49.

[0060] The transmission error detection means 53 extracts all of the monitoring data transmitted from the input slave stations 4 and the input / output slave stations 6 other than its own station based on the digital value of the voltage level of the voltage clock signal delivered from the transmission reception means 41, and converts all of this extracted monitoring data and its own monitoring data delivered from the input means 46 into verification data according to the same rules as the monitoring transmission check conversion in the management data section 22 of the parent station 2. The obtained verification data is then compared with the check data delivered from the management control data extraction means 42, and if the check data and verification data do not match, a logical data value of "1" is delivered to the management monitoring data transmission means 45.

[0061] <Configuration of Output Slave Station> 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 voltage clock 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. Furthermore, when data transmission and reception using the management data area is required, monitoring data is transmitted via the slave station line driver 49. Note that 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 , and an output means 52 .

[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 / reception means 41 of the output slave station 5 discriminates between the voltage level threshold value Est and the threshold value Ect, and passes the digital value of the voltage level of the voltage clock 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 start timing of its own station area by counting the clock voltage period starting from the timing when the start signal ST ends, and activates the control data extraction means 51. Furthermore, if the own station area includes multiple data IO areas, the control data extraction means 51 is activated in the data IO area every time a data IO area appears until the own station area ends.

[0066] When the control data extraction means 51 is validated by the address extraction means 43 , it extracts control data based on the digital value of the voltage level of the voltage clock 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] <Configuration of Input / Output Substation> The input / output substation 6 has the functions of both the input substation 4 and the output substation 5, and has a substation input / output section that combines the configuration of both the substation input section 40 and the substation output section 50. However, since the configuration is essentially the same as the substation input section 40 and the substation output section 50, illustration and description thereof will be omitted.

[0069] In this embodiment, the master station 2 also functions as a check data transmission node, but one of the slave stations 4, 5, and 6 may also function as a check data transmission node, or a device that only converts data into check data and transmits the check data may be provided separately from the master station 2 and the slave stations 4, 5, and 6. The terminator may also function as a check data transmission node. Figure 7 shows the configuration of a terminator that functions as a check data transmission node. In Figure 7, parts that are substantially the same as those in the embodiments shown in Figures 1 to 6 are designated by the same reference numerals, and their descriptions will be simplified or omitted.

[0070] The terminator 30 shown in FIG. 7, which functions as a check data transmission node, includes a slave station line receiver 48, a slave station line driver 49, a data output unit 60, an intermediate voltage reinforcement unit 61, a transmission voltage drop detection unit 62, an external terminal communication unit 63, a reflection suppression unit 64, and an input assistance unit 65.

[0071] The intermediate voltage reinforcing unit 61 reinforces the voltage level of the potential VM higher than the threshold Ect, which indicates a predetermined logical data value ("0" in this embodiment) in the data IO area, thereby suppressing the occurrence of errors due to a drop in the voltage level of the transmission line.

[0072] The transmission voltage drop detector 62 detects that the voltage level of the transmission line has dropped to a predetermined level (16 V in this embodiment), and passes data indicating this drop to the data output unit 60 .

[0073] The data output unit 60 has a transmission / reception means 41, an address extraction means 43, an address setting means 44, a data storage means 66, a check data calculation means 67, and a data transmission means 68, and extracts all of the monitoring data transmitted from the input slave station 4 and the input / output slave station 6, and performs calculations to convert the data into check data according to predetermined rules.

[0074] The data output unit 60 also has a voltage adjustment timing acquisition means 69, which performs voltage adjustment in the data IO area to prevent errors in data transmission. Like the slave stations 4, 5, and 6, the terminator 30 of this embodiment also has an MCU, which is a microcomputer control unit, and this MCU functions as the data output unit 60.

[0075] The transmission / reception means 41 of the data output unit 60 distinguishes between the voltage level threshold value Est and the threshold value Ect, and passes the digital value of the voltage level of the voltage clock signal passed from the slave station line receiver 48 to the address extraction means 43, the data storage means 66, and the voltage adjustment timing acquisition means 69.

[0076] The address extraction means 43 of the data output unit 60 identifies the start signal ST based on the digital value of the voltage level of the voltage clock signal, counts the clock voltage region starting from the timing when the start signal ST ends (in this embodiment, the falling edge), and obtains the timing when this count value matches the address data of the CRC region set by the address setting means 44. Then, the address extraction means 43 that has obtained the start timing of the CRC region enables the data transmission means 68.

[0077] The data storage means 66 extracts the monitoring data transmitted from the input slave station 4 and the input / output slave station 6 based on the digital value of the voltage level of the voltage clock signal delivered from the transmission / reception means 41, and stores all of the data. Then, when the size corresponding to all the monitoring data is reached, all of the data is delivered to the check data calculation means 67.

[0078] The check data calculation means 67 converts the data delivered from the data storage means 66 into check data according to a predetermined rule, and delivers it to the data transmission means 68 .

[0079] If the data transmission means 68 is validated by the address extraction means 43, it transmits the data passed from the check data calculation means 67 as check data via the slave station line driver 49. Furthermore, if data indicating a voltage drop is passed from the transmission voltage drop detection unit 62, it also transmits that data via the slave station line driver 49.

[0080] The voltage adjustment timing acquisition means 69, based on the digital value of the voltage level of the voltage clock signal handed over from the transmission / reception means 41, obtains the timing of the data IO area to enable the reflection suppression unit 64, and also obtains the timing when the potential VL becomes lower than the threshold value Ect to enable the input assistance unit 65.

[0081] The external terminal communication unit 63 communicates with an external terminal device (not shown) that is separate from the terminator 30, and transmits and receives data. When setting the address of the CRC area, the external terminal device transmits the address data sent from the external terminal device to the address setting means 44, and when the external terminal device requests the provision of data, the address setting means 44 transmits the data to the external terminal device.

[0082] When the reflection suppression unit 64 is enabled by the voltage adjustment timing acquisition means 69, the reflection suppression unit 64 maintains the voltage level of the potential VM higher than the threshold Ect in a state higher than the threshold Ect, thereby suppressing fluctuations in the potential VM.

[0083] When the input auxiliary unit 65 is enabled by the voltage adjustment timing acquisition means 69, it suppresses the increase in voltage level that occurs when the number of slave stations 4, 5, and 6 increases, and maintains the voltage level of the potential VL that is lower than the threshold value Ect at a level lower than the threshold value Ect.

[0084] REFERENCE SIGNS LIST 1 Control unit 2 Master station 3, 30 Terminator 4 Input slave station 5 Output slave station 6 Input / output slave station 7 Input unit 8 Output unit 9 Input / output unit 11 Management judgment means 12 Input / output unit 21 Output data unit 22 Management data unit 23 Timing generation unit 24 Master station output unit 25 Master station input unit 26 Input data unit 27 Transmission error judgment unit 31 Oscillator circuit (OSC) 32 Timing generation means 33 Control data generation means 34 Line driver 35 Line receiver 36 Monitoring data extraction means 40 Slave station input unit 41 Transmission reception means 42 Management control data extraction means 43 Address extraction means 44 Address setting means 45 Management monitoring data transmission means 46 Input means 47 Monitoring data transmission means 48 Slave station line receiver 49 Slave station line driver 50 Slave station output unit 51 Control data extraction means 52 Output means 53 Transmission error detection means 60 Data output section 61 Intermediate voltage reinforcement section 62 Transmission voltage drop detection section 63 External terminal communication section 64 Reflection suppression section 65 Input assistance section 66 Data storage means 67 Check data calculation means 68 Data transmission means 69 Voltage adjustment timing acquisition means 70 Input section integrated slave station 80 Output section integrated slave station

Claims

1. A control and monitoring signal transmission system comprising a check data transmission node that converts all of the monitoring data transmitted from a plurality of transmission nodes to a receiving node via a common transmission line into check data according to a predetermined conversion rule, and transmits the check data to the transmission node. The transmission node converts all of the monitoring data into verification data according to the conversion rule, and when the check data and the verification data do not match, outputs data to an NG detection area shared by all of the transmission nodes.

2. The control and monitoring signal transmission system according to claim 1, wherein one of the transmission nodes or the receiving node also serves as the check data transmission node.

3. The plurality of transmission nodes and the receiving node exchange data by a transmission synchronization method via the common transmission line. The data output to the NG detection area is binary data that is either first data indicating that there is a transmission error or second data indicating that there is no transmission error. When the check data and the verification data do not match, the transmission node outputs the first data to the NG detection area, and the data value in the NG detection area after the first data is output is maintained as the first data. The control and monitoring signal transmission system according to claim 1 or 2.

4. The control and monitoring signal transmission system according to claim 1 or 2, wherein the check data is CRC.

5. The exchange of data between the plurality of transmission nodes and the receiving node is performed by superimposing data on a frame repeatedly transmitted from the receiving node. The frame is time-division multiplexed, and a control and monitoring data area in which the data transmission direction is determined and assigned to each of the transmission nodes, and a management data area for use in data exchange with all of the transmission nodes separately from the control and monitoring data area are provided. The control and monitoring signal transmission system according to claim 3.

6. The control and monitoring signal transmission system according to claim 5, wherein the check data is CRC.

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