JP4926234B2 - Signal transmission method in control / monitor signal transmission system - Google Patents

Description

  The present invention includes a single control unit and a plurality of controlled devices, a master station is connected to the control unit and the data signal line, and a plurality of slave stations corresponding to the plurality of controlled devices have a common data signal line The present invention also relates to a signal transmission method suitable for a control / monitor signal transmission system configured to be connected to a corresponding controlled device.

  In a control system having a single control unit and a plurality of controlled devices (consisting of a controlled unit that operates in response to an instruction from the control unit and a sensor unit that transmits information to the control unit), the number of wires Reduction of wiring leads to a reduction in wiring space, a reduction in wiring man-hours, a reduction in device manufacturing time, or downsizing of equipment, thereby making it possible to improve equipment reliability and reduce costs.

  Therefore, attempts have been made to reduce the number of wires in the control system as described above. Specifically, adopt a signal transmission method in which one (1 bit) control signal or sensor signal (input signal from the controlled device) corresponding to each clock is superimposed on the clock signal line including the power supply. Thus, the wiring saving between the control unit and the controlled device is realized.

  Further, in this signal transmission method, Japanese Patent Laid-Open No. 2002-152864 discloses a technique for increasing the signal transmission speed between the control unit and the controlled device. In the control / monitor signal transmission system disclosed herein, a master station is connected to a control unit and a common data signal line, and a plurality of slave stations corresponding to a plurality of controlled devices are connected to a common data signal line and a corresponding data signal line. Connected to the controlled device. Then, the latter half or the first half of each cycle of the clock is further time-divided into a control signal area and a monitor signal area, and the control signal and the monitor signal are superimposed and detected on each. Thereby, in addition to the control signal from the control unit to the controlled unit, the monitoring signal from the sensor unit to the control unit can be superimposed on the clock signal including the power supply. Therefore, bidirectional high-speed signal transmission between the control unit, the controlled unit, and the sensor unit can be realized, and the control signal and the monitoring signal can be output to a common data signal line, and both can be simultaneously transmitted. Can be transmitted in the same direction. As a result, it is not necessary to separately provide a period for transmitting the control signal or the monitoring signal in the common data signal line, and the signal transmission speed (rate) can be increased to twice the conventional speed.

JP 2002-152864 A

  In the transmission system employed in the control / monitor signal transmission system described above, each slave station recognizes a change in voltage level, that is, a change in pulse signal for each cycle of the transmission clock, so that both Direction signal transmission (full duplex) is possible. However, if a voltage change due to noise occurs at the time when the pulse signal changes, that is, at a time other than the rising point or the falling point, it is regarded as a change in the pulse signal even if the change is for a very short time. There is a problem that the pulse signal is recognized as a value different from the originally intended data value.

  Therefore, the present invention provides a control / monitor signal transmission system including a single control unit and a plurality of controlled devices, even if noise is applied to a transmission signal between a master station and a slave station. An object of the present invention is to provide a signal transmission method capable of accurately transmitting the signal.

  The signal transmission method according to the present invention includes a control unit including a control unit and a master station connected to a common data signal line, and a plurality of slave stations connected to the common data signal line and a corresponding controlled device. It is used in a supervisory signal transmission system. The controlled device includes a controlled unit that operates in accordance with an output instruction from the control unit and / or a sensor unit that transmits input information to the control unit. The master station has timing generating means for generating a predetermined timing signal synchronized with a transmission clock having a predetermined cycle. Further, the master station outputs a series of pulse signals as a control data signal to the data signal line according to the value of the control data from the control unit under the control of the timing signal, and the timing Under the control of the signal, the data value of the monitoring data signal superimposed on the series of pulse signals is extracted for each cycle of the transmission clock, and this is transferred to the control unit. Each of the plurality of slave stations extracts a value of each data of the control data signal for each period of the transmission clock under the control of the timing signal, and the local station in the value of each data According to the value of the monitoring data of the corresponding sensor unit for each cycle of the transmission clock signal under the control of the timing signal, and / or The monitoring data signal is superimposed on the series of pulse signals. Then, based on the end of the start signal having a predetermined pulse width, a first signal reception effective time width having a predetermined time width at a predetermined time point at which the control data should be determined in one cycle of the transmission clock signal. And providing a second signal reception effective time width at the start of one cycle of the transmission clock signal, except for the first signal reception effective time width and the second signal reception effective time width of the pulse signal. Not accepted as a change signal.

The value of the control data, are multiple types of pulse width der in one cycle of the transmission clock signal.

  In the present invention, the predetermined time point at which the control data should be determined is all the time points at which the pulse may rise. More specifically, when two types of pulse widths are used, both the time when the pulse rises when the width is long and the time when the pulse rises when the width is short and when the control data should be judged It becomes.

  The signal reception effective time width can be set using four timers. That is, the pulse width takes the first state and the second state, and the start time point of the first signal reception effective time width including the pulse displacement point in the first state is represented by the period in which the pulse is included. Set with the first timer from the beginning. Further, the start point of the first signal reception effective time width including the pulse displacement point in the second state is set by the second timer with the start of the cycle including the pulse as a base point. Furthermore, the start point of the second signal reception effective time width is set by the third timer with the start of the cycle including the pulse as a base point. Then, a time width between the first signal reception effective time width and the second signal reception effective time width is set by a fourth timer.

  In the signal transmission system according to the present invention, in one cycle of a series of pulse signals transmitted between the master station and the slave station, the start point of one cycle of the transmission clock signal and the control are transmitted to the slave station. A signal reception effective time width having a predetermined time width is provided at a predetermined time point at which data should be determined, and the slave station does not accept the change signal of the pulse signal except for this signal reception effective time width. Therefore, even when noise is added to the transmission signal, the noise is not mistaken as a change in the pulse signal, and therefore the data value can be transmitted accurately. In addition, if the time width of the signal reception effective time width is extremely short as long as the slave station can detect the change of the pulse signal, the possibility that noise will be added to the signal reception effective time width is extremely low. Practical use is possible.

It is a time chart figure of the transmission signal which shows the signal reception effective time width set in the Example of the signal transmission system based on this invention. 1 is a system configuration diagram showing a schematic configuration of a control / monitor signal transmission system employing the same signal transmission method. It is a system configuration | structure figure of a master station. It is a block diagram of a slave station output unit. It is a block diagram of a slave station input part. It is a time chart figure of the signal transmitted / received between a master station and a slave station. A signal extracted from a transmission signal in a slave station according to a conventional signal transmission method is shown, (a) is a time chart of a signal extracted when noise is not added to the transmission signal, and (b) is a transmission signal. It is a time chart figure of the signal extracted when there is noise on. It is a time chart figure of the signal transmitted / received between the master station and the slave station in still another embodiment that adopts high and low voltage levels as an expression format of monitoring data.

An embodiment of a signal transmission method according to the present invention will be described with reference to FIGS.
First, the configuration of a control / monitor signal transmission system employing this signal transmission method will be described. As shown in FIG. 2, the control / monitor signal transmission system includes a master station 6 connected to the control unit 1 and common data signal lines DP and DN (hereinafter referred to as data signal lines DP and DN), A plurality of slave stations 2 connected to the data signal lines DP and DN and the corresponding controlled devices 5 are provided. The controlled device 5 includes a controlled unit 51 that operates according to an output instruction from the control unit 1 and a sensor unit 52 that transmits input information to the control unit 1. The controlled unit 51 includes various components constituting the controlled device 5, such as an actuator, a (stepping) motor, a solenoid, a solenoid valve, a relay, a thyristor, and a lamp. On the other hand, the sensor unit 52 is selected according to the corresponding controlled unit 51, and includes, for example, a reed switch, a micro switch, a push button switch, an optical sensor, and the like, and outputs an on / off state (binary signal).

  The control unit 1 is, for example, a programmable controller, a computer, and the like, and includes an output unit 11 that transmits control data 13 and an input unit 12 that receives sensor data (monitoring data signal data) 15 from the controlled device 5 side. These output unit 11 and input unit 12 are connected to the master station 6.

  As shown in FIG. 3, the master station 6 includes an output data unit 61, a timing generation unit 63, a master station output unit 64, a master station input unit 65, and an input data unit 66.

  The output data unit 61 passes the parallel data received as the control data 13 from the output unit 11 of the control unit 1 to the master station output unit 64. This control data 13 is used to instruct the controlled unit 51 to operate.

  The timing generation unit 63 includes an oscillation circuit (OSC) 71 and a timing generation unit 72. Based on the OSC 71, the timing generation unit 72 generates a timing clock of the transmission system and passes it to the master station output unit 64. The master station output unit 64 includes a control data generation unit 73 and a line driver 74. The control data generation unit 73 receives a series of pulses based on the data received from the output data unit 61 and the timing clock received from the timing generation unit 63. A control data signal which is a state signal is generated and sent to the data signal lines DP and DN via the line driver 74. Here, the control data signal transmitted to the data signal lines DP and DN corresponds to a series of pulse signals in the present invention, but hereinafter, the control data signal flowing through the data signal lines DP and DN is transmitted. This is called a clock signal. The line driver 74 is also supplied with power from the DC power source 75 and supplies circuit power for the slave station 2 via the common data signal lines DP and DN together with the transmission clock signal.

  The master station input unit 65 includes a monitoring signal detection unit 76 and a monitoring data extraction unit 77, and sends input data to the input data unit 66. The monitoring signal detection means 76 detects the monitoring data signal sent from the slave station 2 via the common data signal lines DP and DN. The monitoring data signal transmitted from the slave station 2 is a signal indicating whether or not the detection target in the sensor unit 52 is detected as a current level, and is received sequentially from each slave station 2 after the start signal is transmitted. It has become. The monitoring data of the monitoring data signal is extracted by the monitoring data extraction unit 77 in synchronization with the signal of the timing generation unit 72 and sent to the input data unit 66 as serial input data.

  The input data unit 66 that has received the serial input data from the master station input unit 65 converts the serial input data into parallel data, and delivers it as sensor data 15 to the input unit 12 of the control unit 1.

  The master station 6 also has a transmission bleeder current circuit 67 as a transmission interface circuit. The transmission bleeder current circuit 67 is connected to the line driver 74 in the master station output unit 64 and stabilizes the transmission path between the data signal lines DP and DN.

  The slave station 2 includes a slave station output unit 30 and a slave station input unit 40, each of which is connected to the data signal lines DP and DN, and the signal received from the sensor unit 52 is used as a monitoring data signal. And necessary information is extracted from the transmission clock signal transmitted on the data signal lines DP and DN, and the controlled unit 51 is operated.

  As shown in FIG. 4, the slave station output unit 30 includes an address setting unit 31, an address extraction unit 32, a slave station data output unit 33, an output data unit 34, and a control data signal extraction unit 36. Further, a connection terminal outN is provided, and the controlled unit 51 is connected thereto.

  The slave station output unit 30 is equipped with a microcomputer control unit (MCU) 39, and includes an address setting unit 31, an address extraction unit 32, a slave station data output unit 33, and an output data unit 34. Each processing is performed by the MCU 39. Calculations and storages required for each process are executed using the CPU, RAM, and ROM provided in the MCU 39. However, in FIG. 4, the relationship between the CPU, RAM, and ROM in each process is omitted for convenience of explanation.

  The address setting means 31 recognizes an address value set by an address setting switch (not shown) and delivers it to the address extraction means 32. The address setting is not limited to a mechanical method using a switch or the like. For example, a preset value may be transmitted from the master station 6 and stored.

  The address extracting means 32 is handed over the local station address recognized by the address setting means 31 and is transmitted with a transmission clock signal from the data signal lines DP and DN via the control data signal extracting means 36. The address extraction unit 32 obtains data of its own station address based on these pieces of information, and delivers the data to the slave station data output unit 33. The data delivered to the slave station data output means 33 is further delivered to the output data unit 34, and the controlled unit 51 operates based on the data. The series of processing is performed in synchronization with the clock of the transmission clock signal transmitted to the data signal lines DP and DN, that is, under the control of the timing signal.

  Although the slave station output unit 30 does not have a dedicated power supply, it is used inside the slave station output unit 30 from a transmission clock signal on which power is superimposed supplied from the common data signal lines DP and DN. The power supply voltage is generated by a diode, a capacitor, and a three-terminal power supply element.

  As shown in FIG. 5, the slave station input unit 40 includes an address setting unit 41, an address extraction unit 42, a slave station data input unit 43, an input data unit 44, and a control data signal extraction unit 46. Moreover, the connection terminal inN is provided and the sensor 52 is connected there. Further, similarly to the slave station output section 30, the slave station input section 40 is also equipped with a microcomputer control unit (MCU) 49, and includes an address setting means 41, an address extraction means 42, a slave station data input means. 43 and the input data unit 44 are processed by the MCU 49. The address setting means 41, the address extraction means 42, and the control data signal extraction 46 have substantially the same configuration as the address setting means 31, the address extraction means 32, and the control data signal extraction means 36 of the slave station output unit 30. Since the operation is substantially the same, the description thereof is omitted. Also, in FIG. 6, as in FIG. 5, the relationship between the CPU, RAM, and ROM in each process is omitted for convenience of explanation.

  The input data unit 44 passes one or a plurality of (bit) data signals input from the sensor unit 52 to the slave station data input unit 43. The data delivered here is held in the slave station data input means 43. In the slave station data input means 43, when an address is input from the address extraction means 42, the output of the Iout0 signal is set to “on” or “off” according to the held data or data. When the Iout0 signal is “on”, the transistor 47 is “on”, and the monitoring data signal is output to the data signal lines DP and DN. Here, the slave station data input means 43 performs parallel / serial conversion on the monitoring data signal, and the output monitoring data signal becomes a serial signal. At this time, the data value of the monitoring data signal is expressed as a current level in the first half (period of low potential level) of one cycle of the transmission clock signal.

  Similarly to the slave station output unit 30, the slave station input unit 40 also uses a diode, a capacitor, and a three-terminal power element to convert the power supply voltage used in the slave station input unit 40 from the transmission clock signal superimposed with the power supply. Producing.

Next, a signal transmission system of the control / monitor signal transmission system will be described.
The data value of the transmission clock signal sent from the master station output unit 64 to the data signal lines DP and DN is expressed by the width of the voltage level high period (voltage pulse width) in one cycle of the transmission clock. In this embodiment, as shown in FIG. 1, the second half of one cycle is set to a high potential level (+24 V in this embodiment) and the first half is set to a low potential level (+19 V in this embodiment). Then, the width of the voltage pulse is expanded as indicated by the broken line in FIG. 1 according to the value of each data of the control data 13 input from the control unit 1. In addition, an address (indicated as ADR0, ADR1, and ADR2 in FIG. 1) is assigned for each cycle of the transmission clock signal, and the slave station 2 controls the local station to receive by a method of counting this address. The signal is captured.

  FIG. 6 shows an example of the transmission clock signal. In this embodiment, the control data values (output data) at the address numbers 0, 1, 2, and 3 represent "0", "0", "1", and "0", respectively. On the other hand, the value (input data) of the monitoring data is expressed as a current level in the first half (period of low potential level) of one cycle of the transmission clock signal. In this embodiment, when the data value of the monitoring data signal is “1”, a current (for example, 30 mA) greater than or equal to a predetermined value Ith is passed, and when it is “0”, it is expressed as only a bleeder current (for example, 10 mA). Has been. Therefore, the monitoring data at the address numbers 0, 1, 2, and 3 represent “0”, “0”, “1”, and “0”, respectively.

  Although not shown in FIG. 6, as shown in FIG. 1, a start signal (StartBit) is formed in the transmission clock signal in order to determine the start of address counting. The start signal is a signal having the same potential level as the high potential level of the transmission clock signal and longer than one cycle of the transmission clock signal.

  The transmission clock signal shown in FIG. 6 is also used in the conventional transmission method, and if it is in this format, noise on the transmission clock signal is mistaken as a change in the pulse signal. For example, if there is no noise, even if the extracted signal is as shown in FIG. 7A, a voltage change exceeding the detection threshold voltage Vth occurs due to the noise, which is a pulse signal. As shown in FIG. 7B, a completely different signal from the intended one is extracted and the address number is misidentified. Therefore, in this embodiment, as shown in FIG. 1, by setting the signal reception effective time width, it is possible to prevent the noise on the transmission clock signal from being misidentified as a change in the pulse signal.

  As shown in FIG. 1, as the signal reception effective time width, when the voltage pulse width of the high potential level is long, the first signal reception effective time width Te1a is the voltage pulse of the high potential level at the time when the voltage pulse rises. When the width is short, the first signal reception effective time width Te1b is set at the time when the voltage pulse rises, and the second signal reception effective time width Te2 is set at the start time of one cycle of the transmission clock signal. The slave station 6 includes first, second, third, and fourth timers, and the start time of the first signal reception effective time width Te1a, Te1b and the second signal reception effective time width Te2 is a transmission clock signal. The first, second and third timers are set with the start P0, P1 or P2 as the base point. Then, time widths of the first signal reception effective time widths Te1a and Te1b and the second signal reception effective time width Te2 are set by the fourth timer.

  The second signal reception effective time width Te2 includes a falling edge of a pulse that is a start point of one cycle of the transmission clock signal. Therefore, if the counting of the address of the slave station 6 is advanced only when the falling edge of the pulse is detected in the second signal reception effective time width Te2, the transmission clock signal other than the second signal reception effective band Te2 is used. The address can be accurately counted without counting the potential change caused by the added noise.

  The slave station 6 that has determined that the count corresponds to its own station, that is, the address corresponding to its own station, superimposes the monitoring data signal on the low potential level that is the first half of one cycle of the transmission clock. The pulse width is determined by detecting the rise of the pulse in the first signal reception effective time width Te1a, Te1b, and the value indicated by the pulse width is extracted as control data. Here, a potential change other than the first signal reception effective time width Te1a, Te1b is not detected. Therefore, the potential change caused by noise on the transmission clock signal is not mistaken for the rise of the voltage pulse.

  In the transmission clock signal shown in FIG. 1, the signal reception effective time width is not set at the start time point P0 of the first cycle of the transmission clock signal, but the second signal reception effective time width may be set at this time point. . The second signal reception effective time width including the time point P0 can be set based on the start of the start signal, and in this case, there is an advantage that the start of the transmission clock signal can be detected more accurately.

  In this embodiment, the width of the voltage pulse is adopted as the expression format of the control data, and the presence / absence of current is adopted as the expression format of the monitoring data. However, the expression format is not limited, and the voltage pulse level, current pulse Other expression formats such as the width or level may be adopted as appropriate. FIG. 9 shows an embodiment in which a voltage pulse level is adopted as the monitoring data expression format.

DESCRIPTION OF SYMBOLS 1 Control part 2 Slave station 5 Controlled apparatus 6 Master station 11 Output unit 12 Input unit 13 Control data 15 Sensor data 30 Slave station output part 31 Address setting means 32 Address extraction means 33 Slave station data output means 34 Output data part 36 Control Data signal extraction means 39, 49 MCU
40 Slave station input unit 41 Address setting unit 42 Address extraction unit 43 Slave station data input unit 44 Input data unit 46 Control data signal extraction unit 47 Transistor 51 Controlled unit 52 Sensor unit 61 Output data unit 63 Timing generation unit 64 Master station output Unit 65 Master station input unit 66 Input data unit 67 Transmission bleeder current circuit 71 Transmitter 72 Timing generation unit 73 Control data generation unit 74 Line driver 75 DC power supply 76 Monitoring signal detection unit 77 Monitoring data extraction unit Te1a, Te1b First signal reception Effective time width Te2 Second signal reception effective time width

Claims (1)

A master station connected to the control unit and a common data signal line, and a plurality of slave stations connected to the common data signal line and the corresponding controlled device;
The controlled device includes a controlled unit that operates according to an output instruction of the control unit and / or a sensor unit that transmits input information to the control unit,
The master station has timing generation means for generating a predetermined timing signal synchronized with a transmission clock having a predetermined cycle, and according to the value of control data from the control unit under the control of the timing signal And outputting a series of pulse signals as control data signals to the data signal line, and monitoring data signals superimposed on the series of pulse signals for each cycle of the transmission clock under the control of the timing signal Data value is extracted and passed to the control unit,
Each of the plurality of slave stations extracts a value of each data of the control data signal for each period of the transmission clock under the control of the timing signal, and the local station in the value of each data According to the value of the monitoring data of the corresponding sensor unit for each cycle of the transmission clock signal under the control of the timing signal, and / or In the control / monitor signal transmission system for superimposing the monitor data signal on the series of pulse signals,
Provided is a first signal reception effective time width having a predetermined time width at a predetermined time point at which the control data should be determined in one cycle of the transmission clock signal, based on the end of the start signal having a predetermined pulse width, A second signal reception effective time width is provided at the start of one cycle of the transmission clock signal, and other than the first signal reception effective time width and the second signal reception effective time width, it is not accepted as a change signal of the pulse signal ,
The value of the control data is a plurality of types of pulse widths in one cycle of the transmission clock signal.
The pulse width takes the first state and the second state, and the start time of the first signal reception effective time width including the pulse displacement point in the first state is defined as the start of the period in which the pulse is included. The first timer is set as a base point, the start point of the first signal reception effective time width including the pulse displacement point in the second state is set as the base point, and the start point of the cycle including the pulse is set as the second timer And the start time of the second signal reception effective time width is set by a third timer based on the start of the period including the pulse, and the first signal reception effective time width and the second signal reception are set. A signal transmission method characterized in that a time width of an effective time width is set by a fourth timer .

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