JP3409111B2 - Signal output device, signal input device and signal input / output system between devices - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device that outputs a signal (for example, a sensor) and a device that inputs a signal from this signal output device (for example, a slave station such as a remote terminal,
Or a master station such as a programmable controller),
Involved in the signal input / output system between these devices,
In particular, it relates to signal wiring between these devices.

[0002]

2. Description of the Related Art Referring to FIG. 4, as a signal input / output system, a master station 1 such as a programmable controller and a plurality of slave stations such as remote terminals connected to the master station 1 via a cable 2 are connected. 3 and the limit switch and the sensor 4 are connected to each slave station 3,
Alternatively, there is one to which an actuator, relay 5, etc. are connected. In such a system, an ON / OFF control signal from the sensor 4 or the like connected to the slave station 3 is transmitted to the master station 1 via the slave station 3, and the master station 1 fetches this control signal and is preset. There is a system in which arithmetic processing is performed in accordance with a certain program, and a corresponding drive signal is output to an actuator, a relay 5 or the like via the slave station 3 to control a machine tool or the like.

[0003]

In the cable 2 connecting such a system, a signal is transmitted from the sensor 4 side to the master station 1 side via the slave station 3, and for supplying and receiving power. Thus, the wiring in the cable 2 is composed of at least a power supply line 2a, a ground line 2b, and a control signal line 2c. In this case, on the sensor 4 side, if the sensor 4 is installed as described above, the sensor function margin is self-diagnosed for environmental changes around the sensor 4 after the sensor 4 is installed, such as changes in temperature, humidity, and pressure. When the diagnosis result is transmitted to the master station 1 via the slave station 3 as a self-diagnosis signal, an extra self-diagnosis signal line 2d for that purpose is required.

A circuit of a main part of the sensor 4 having a self-diagnosis function and a circuit of a main part of the slave station 3 connected to the sensor 4 through the cable 2 will be described with reference to FIG. Here, the sensor 4 will be described by taking a proximity sensor as an example. The sensor 4 has a power supply terminal 6 connected to the power supply line 2a, a signal output terminal 7 connected to the control signal line 2c, and a self-diagnosis signal line 2
It has a total of four output terminals including a signal output terminal 8 to which d is connected and a ground terminal 9 to which the ground line 2b is connected. Further, the sensor 4 has a transistor 10 whose base receives the control signal S1 and a base 11 which receives the self-diagnosis signal S2. And
The transistor 10 is turned on or off when the control signal S1 which is a high-level or low-level voltage is applied to the base based on the detection result that the target object is approached or not approached by the sensor 4. The control signal S1 can be output. The transistor 11 conducts self-diagnosis by the sensor 4 itself, and a self-diagnosis signal S2, which is a high-level or low-level voltage, is applied to its base depending on whether the result of the self-diagnosis is normal or abnormal, and the transistor 11 becomes conductive. Alternatively, the self-diagnosis signal S2 can be output by not conducting.

The slave station 3 has a power supply terminal 12 connected to the power supply line 2a, an input terminal 13 connected to the control signal line 2c, and an input terminal 14 connected to the self-diagnosis signal line 2d. The slave station 3 has a power terminal 12 and an input terminal 1.
3 has a light emitting diode in a photo coupler 16 via a resistor 15 and also has a light emitting diode in a photo coupler 18 between a power supply terminal 12 and an input terminal 14 via a resistor 17. There is. Here, although not shown, other sensors and the like are similarly connected to the slave station 3. An input / output power supply 19 is inserted and connected between the ground wire 2b of the sensor 4 and the power supply wire 2a.

In any case, if the sensor 4 has a self-diagnosis function, even if the power supply line 2a and the ground line 2b are considered separately, the number of output terminals is larger than that of the sensor having no self-diagnosis function. In addition to the output terminal 7 for outputting the self-diagnosis signal, the output terminal 8 for outputting the self-diagnosis signal is required. Therefore, the number of wires for connecting the sensor 4 and the slave station 3 is the same as that of the self-diagnosis signal output line 2d. There is a problem that extra wiring is required, which leads to an increase in installation cost in the system.

In order to eliminate the increase in the number of wires, which is the above-mentioned problem, it is possible to eliminate the self-diagnosis function output line 2d and output the self-diagnosis signal S2 to the control signal output line 2c together with the control signal S1 in a time division manner. In such a case, high-speed self-diagnosis cannot be performed because the real-time self-diagnosis is lost, and naturally, a new problem occurs that the high-speed response of the control signal is impaired.

Therefore, according to the present invention, even if a device such as a sensor having a self-diagnosis function is used, the number of wires is the same as the number of wires in a device having no self-diagnosis function, and the other system is used. It is a problem to be solved that the laying cost can be reduced and the above-mentioned high-speed response can be achieved at the same time.

[0009]

In the present invention, the signal is
The input device has a cable that has a power line, ground line, and signal line.
Signal output device connected via a cable
Output signal given to one output terminal connected to signal line
Is the voltage whose voltage is about to be transmitted to the signal input device.
Information about each state in at least two signals
Depending on the combination of information, it is divided into a predetermined number of levels
And the combination from only the output terminal
The above problem is solved by outputting a signal of a corresponding voltage .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, the sensor 4 in the system shown in FIG.
The slave station 3 will be described. In short, the present invention can be applied to any device that has a self-diagnosis function and can output the self-diagnosis signal as well as outputting a control signal, such as a sensor. The device to which item (1) is applied is not limited to the sensor described below, but includes devices such as a sensor that output a control signal and a self-diagnosis signal as signal output devices. Further, in the present invention, the slave station 3 can be similarly applied to all devices to which a signal is input from the signal output device such as the sensor 4. Therefore, in the present invention, in the slave station described below, The present invention is not limited to such devices, but is applicable to all signal input devices that input signals from devices such as sensors. Further, in the present invention, a device such as a master station is also included in the above signal input device because a sensor or the like is connected to the master station 1 via a cable and signals can be input / output from this point. And

An embodiment of the present invention will be described below with reference to FIG. 1 by applying it to a sensor 4 and a slave station 3 in a control system.

In this embodiment, the sensor 4 has a condition circuit I1 and an output circuit I2. Condition circuit I
1 is composed of three gate circuits G1, G2 and G3. The control signal S1 is commonly input to one input section of each of the gate circuits G1, G2, and G3, and the self-diagnosis signal S2 is commonly input to the other input section. Therefore, each gate circuit G1, G2, G
Outputs A, B, and C according to the truth table shown in FIG. 2 are output from the respective output units. The outputs A, B and C will be described. The upper side of the truth table of FIG. 2 is each gate circuit G1, G2 in the condition circuit I1.
Control signal S1 applied to one input of each G3
And the self-diagnosis signal S2. In this truth table, “ON” indicates that the signal level is high level, and “OFF” indicates that the signal level is low level.

For example, in the first combination, when the control signal S1 and the self-diagnosis signal S2 input to the respective input portions of the respective gate circuits G1, G2, G3 are both at high level, that is, both are ON, only the output A of the gate circuit G1 is output. Is ON
That is, at the high level, the outputs B and C of the other gate circuits G2 and G3 are both OFF, that is, at the low level.

In the second combination, each gate circuit G
The control signal S1 input to the input section of each of G1, G2 and G3 is the ON state value of the two ON and OFF state values, and the self-diagnosis signal S2 is the OFF state of the two ON and OFF state values. When it is a value, only the output C of the gate circuit G3 is ON, that is, at the high level, and the other gate circuits G1 and G3
The outputs A and B of 2 are both OFF, that is, low level.

In the third combination, each gate circuit G
When the control signal S1 input to each of the input sections of G1, G2 and G3 is OFF and the self-diagnosis signal S2 is ON, only the output B of the gate circuit G2 is ON, that is, at the high level, and the other gate circuits G1 and G3 Both outputs A and C are OFF, that is, low level.

In the fourth combination, each gate circuit G
When the control signal S1 input to the input section of each of G1, G2 and G3 is OFF and the self-diagnosis signal S2 is ON, the outputs A, B and C of each gate circuit G1, G2 and G3 are both OFF, that is, both are low level. Is shown.

The output circuit I2 is connected to the transistors T1, T2 and T3 whose bases are individually connected to the output parts of the gate circuits G1, G2 and G3 respectively, and to the collector of the first transistor T1. It is configured to have a first Zener diode Z1 and a second Zener diode Z2 connected to the collector of the second transistor T2.

The output A of the gate circuit G1 is input to the base of the first transistor T1, and the second transistor T1 is supplied.
The output B of the gate circuit G2 is input to the base of 2, and the output C of the gate circuit G3 is input to the base of the third transistor T3. Here, the Zener voltage VZ1 of the first Zener diode Z1 is 0.3.Vcc, and the Zener voltage VZ2 of the second Zener diode Z2 is 0.
7 · Vcc.

In the sensor 4 having the above-mentioned condition circuit I1 and output circuit I2, the power supply terminal Vcc1 and the first
Output terminal OUT1 and ground terminal GND1. The first transistor T is connected to the first output terminal OUT1.
The collector of 1 is directly connected to the collector of the second transistor T2 via the first Zener diode Z1, the collector of the second transistor T2 is directly connected to the collector of the third transistor T3, respectively. The ground terminal GND1 is connected to the transistors T1 and T
The emitters of 2 and T3 are commonly connected.

Therefore, in the sensor 4 of this embodiment, the control signal S1 and the self-diagnosis signal S2 are the same as in the conventional case.
Are not output from separate output terminals, but are commonly output from only the first output terminal OUT1 as described later.

The output from the first output terminal OUT1 of the sensor 4 will be described.

First, when the control signal S1 and the self-diagnosis signal S2 are in the first combination, the output A of the first gate circuit G1 among the gate circuits G1, G2, G3 forming the condition circuit I1 is obtained. Only becomes ON, that is, high level. Therefore, in the case of this first combination, since the high-level output A of the first gate circuit G1 is input to the base of the first transistor T1, only this first transistor T1 becomes conductive, and Each of the second and third transistors T2 and T3 of is non-conductive. Then, the first transistor T1 becomes conductive, and the output voltage of the first output terminal OUT1 becomes the Zener voltage VZ1.
(= 0.3 Vcc).

In the case of the second combination, similarly, only the third transistor T3 becomes conductive, so that the output of the output terminal OUT1 becomes substantially zero only by the collector-emitter voltage of the third transistor T3 in the conductive state. The voltage will be close.

In the third combination, similarly, only the second transistor T2 becomes conductive, so that the output terminal O
The output of UT1 is the Zener voltage VZ2 (= 0.7Vcc)
Becomes

In the fourth combination, similarly, since all the transistors T1, T2 and T3 are non-conductive, the output of the output terminal OUT1 becomes Vcc.

Next, the configuration of the slave station 3 will be described. The slave station 3 has a power supply terminal Vcc2, a first input terminal IN1 and a ground terminal GND2, and has a power supply terminal Vcc2 and a first power supply terminal Vcc2.
The light emitting diode in the first photocoupler P1 for transmitting the control signal S1 is provided between the input terminal IN1 and the input terminal IN1. The slave station 3 also has comparators C1 and C2. The positive input part (+) of the first comparator C1 is connected to the first input terminal IN1, and the negative input part (−) is connected to the positive electrode of the first reference power source E1 (voltage is 0.25 Vcc). , The second comparator C2 has a negative input (-)
Is also connected to the first input terminal IN1 and the positive input portion (+) is connected to the positive electrode of the second reference power source E2 (voltage is 0.75 Vcc). Both of these reference power sources E1 and E2
Each negative electrode is commonly connected to the ground terminal GND2. Further, a light emitting diode in the second photocoupler P2 for transmitting the self-diagnosis signal S2 is connected between the output of each of the comparators C1 and C2 and the power supply terminal Vcc2. Here, as described above, the first reference power source E
1 is a voltage of 0.25 Vcc lower than the Zener voltage VZ1 of 0.3 Vcc, and the second reference power source E2 is a voltage of 0.75 Vcc higher than the Zener voltage VZ2 of 0.7 Vcc.

The corresponding terminals of the sensor 4 and the slave station 3 described above, that is, the power supply terminals Vcc1 and Vcc2 are the power supply line L _VCC , and the first output terminal OUT1 and the first input terminal IN1 are the signal line L1. The ground terminal GND1 and the ground terminal GND2 are connected by the ground line L _GND .

The operation will be described below with reference to FIGS. 2 and 3.

In this description, for easy understanding, it is assumed that when the self-diagnosis signal S2 is ON, the sensor 4 self-diagnoses as being abnormal, and when it is OFF, it is self-diagnosing as normal. To do. Here, the description of FIG. 2 is omitted because it has been described above, but in FIG. 3, the vertical axis represents the voltage level of the output terminal OUT1, and the self-diagnosis signal S2 is OFF from substantially 0 to 0.25 Vcc.
, 0.25 Vcc to 0.75 Vcc are areas where the self-diagnosis signal S2 is ON, and 0.75 Vcc to Vcc are areas where the self-diagnosis signal S2 is OFF. Further, when the voltage level of the output terminal OUT1 is Vcc, the control signal S1 is OFF, and at other voltage levels, the control signal S1 is ON.

(1) In the first combination in which the control signal S1 is ON, that is, the high level, and the self-diagnosis signal S2 is ON, that is, the high level, and the self-diagnosis is abnormal: At this time, 1st photocoupler P1 and 2nd
It is necessary to drive the respective light emitting diodes together with the photocoupler P2.

Therefore, in the sensor 4, only the output A of the first gate circuit G1 of the condition circuit I1 is turned ON, that is, becomes the high level, and only the first transistor T1 of the output circuit I2 becomes conductive. Therefore, the voltage level at the first output terminal OUT1 of the sensor 4 becomes 0.3 Vcc of the first Zener voltage VZ1. Here, the saturation voltage of the collector-emitter voltage of the first transistor T1 is ignored. The voltage level at the output terminal OUT1 is higher than the voltage of the first reference power supply E1 (0.25 Vcc) of the first comparator C1 of the slave station 3, but the second reference power supply E2 (0 0.75 Vc
Since the voltage level of the output terminal OUT1 is smaller than the voltage of c), that is, the voltage level of the output terminal OUT1 is within the voltage range region of 0.25 Vcc to 0.75 Vcc, both output levels of the output parts of the comparators C1 and C2 are low level. , The light emitting diode in the second photocoupler P2 is driven to emit light. As a result, a signal indicating that the self-diagnosis is abnormal is transmitted from the sensor 4. In this case, as shown in FIG. 3, when the self-diagnosis signal S2 is ON, the voltage level of the output terminal OUT1 is 0.25 Vcc to 0.75 Vcc. Since the voltage level of the output terminal OUT1 is Vcc or lower, the light emitting diode in the first photocoupler P1 between the power supply terminal Vcc2 and the output terminal OUT1 is also driven to emit light.

(2) In the second combination in which the control signal S1 is ON, that is, the high level, and the self-diagnosis signal S2 is OFF, that is, the low level, and the self-diagnosis is normal: At this time, The light emitting diode in the first photo coupler P1 needs to be driven to emit light, while the light emitting diode in the second photo coupler P2 does not need to be driven to emit light.

Therefore, in the sensor 4, only the output C of the third gate circuit G3 of the condition circuit I1 is ON, that is, the high level, and only the third transistor T3 of the output circuit I2 is conductive. Therefore, the voltage of the first output terminal OUT1 of the sensor 4 becomes substantially zero. This voltage is
Since the output voltage of the first comparator C1 becomes high level, the second comparator C1 has a voltage lower than that of the reference power sources E1 and E2 of the slave stations 3, respectively. The output level of C2 becomes a low level, and therefore, the light emitting diode in the second photocoupler P2 is not driven and thus does not emit light. As a result, the signal indicating that the self-diagnosis is normal is transmitted from the sensor 4 to the slave station 3. The light emitting diode in the first photocoupler P1 is also the third transistor T3.
Is driven to emit light, and the control signal S1 from the sensor 4 is transmitted to the slave station 3.

(3) In the third combination in which the control signal S1 is OFF, that is, low level, and the self-diagnosis signal S2 is ON, that is, high level, and the self-diagnosis is abnormal:
At this time, the light emitting diode in the first photocoupler P1 of the slave station 3 does not need to be driven to emit light, while the light emitting diode in the second photocoupler P2 needs to be driven to emit light.

Therefore, in the sensor 4, only the output B of the second gate circuit G2 of the condition circuit I1 is ON, that is, the high level, and only the second transistor T2 of the output circuit I2 is conductive. Therefore, the voltage of the first output terminal OUT1 of the sensor 4 is equal to the second Zener diode Z2.
Of the zener voltage VZ2 of 0.7Vcc. This voltage is larger than 0.25 Vcc which is the reference voltage of the first comparator C1 of the slave station 3, and the second comparator C1,
Since it is smaller than 0.75Vcc which is the reference power source E2 of C2, both the output levels of the comparators C1 and C2 are low level, and therefore the light emitting diode in the second photocoupler P2 is driven to emit light. As a result, a signal indicating that the self-diagnosis is abnormal is transmitted from the sensor 4 to the slave station 3. Further, the light emitting diode in the first photocoupler P1 is also driven to emit light by the conduction of the second transistor T2, and the control signal S1 from the sensor 4 is transmitted to the slave station 3.

(4) In the fourth combination in which both the control signal S1 and the self-diagnosis signal S2 are OFF, that is, low level, and the self-diagnosis of the sensor 4 is normal: At this time, the first of the slave stations 3 Neither the light emitting diode in the photo coupler P1 nor the light emitting diode in the second photo coupler P2 needs to be driven to emit light.

Therefore, in the sensor 4, the output of any of the gate circuits G1, G2 and G3 of the conditional circuit I1 is O.
FF, that is, a low level, causes none of the transistors T1, T2, T3 of the output circuit I2 to become non-conductive. Therefore, the power supply voltage Vcc is output as the output voltage from the first output terminal OUT1 of the sensor 4. This output voltage is applied to the first and second comparators C1 and C1 of the slave station 3.
The output level of the first comparator C1 is a low level and the output level of the second comparator C2 is a high level because it is higher than either of the voltages of the reference power sources E1 and E2 of C2. P
The light emitting diode in 2 is not driven to emit light. As a result, a signal indicating that the self-diagnosis is normal is transmitted from the sensor 4 to the slave station 3. Further, neither the light emitting diode in the first photocoupler P1 is driven to emit light because none of the transistors T1, T2 and T3 are non-conductive, and thus the control signal S1 from the sensor 4 is transmitted to the slave station 3. become.

As described above, in this embodiment, as shown in FIG. 3, the first output terminal OU of the sensor 4 is used.
The level of the output voltage from T1 is 0 to 0.25 Vcc,
When 0.75Vcc to Vcc, the self-diagnosis is OFF, that is, a signal indicating that the sensor 4 is not abnormal is transmitted, and when the output voltage level is 0.25Vcc to 0.75Vcc, the self-diagnosis is ON, that is, the sensor 4 is abnormal. The same first output terminal OU for transmitting the signal
The control signal S1 of the sensor 4 can be transmitted from T1 to the slave station 3. That is, conventionally, two signal lines were required to transmit the control signal S1 and the self-diagnosis signal S2 from the sensor 4 to the slave station 3, but in the present embodiment, only one signal line is required. As a result, the number of wirings is reduced, and the wiring laying cost in the system using this sensor can be reduced. Further, since the control signal S1 and the self-diagnosis signal S2 can be transmitted at the same time, for example, when the control signal S1 and the self-diagnosis signal S2 are transmitted in a time-division manner by one signal line, there is no real-time transmission of these signals. On the other hand, in this embodiment, there is real-time property,
Therefore, the high speed response is improved.

[0039]

As described above, according to the signal output device such as the sensor of the present invention, the voltage applied to one output terminal is divided into a predetermined number of levels in accordance with a combination of information regarding the states of at least two signals. Since the information regarding the control signal and the self-diagnosis signal is output as two signals from one output terminal, the number of signal wirings in devices such as sensors can be reduced. Further, even when both of these signals are output by one signal line, the information on the signals can be output in real time, so that the high-speed response can be improved.

According to the signal input device of the present invention, the input terminal connected to the output terminal of the signal output device, and the first and second operating elements for operating according to the states of the both signals. A circuit for operating each of the operating elements, the circuit comprising a voltage region for operating each of the operating elements and a voltage region for not operating for a level of a voltage applied from the output terminal to the input terminal. Therefore, even if the signal output device such as a sensor is only connected by one signal line, the control signal is obtained through the operation of the first operation element, and the self-diagnosis signal is obtained. The information of both of these signals can be input through the operation of the second operating element, which simplifies the wiring and, even if the wiring is simplified, the information of these signals can be input. Speed response of the input is not intended to be the inhibition of.

According to the signal input / output system of the present invention, it has the signal output device and the signal input device, and the output terminal of the signal output device and the input terminal of the signal input device are connected by wiring. Therefore, it is possible to reduce the installation cost with simple wiring. In addition, the system can input and output signals at high speed, and the system can be excellent in high-speed response.

[Brief description of drawings]

FIG. 1 is a diagram showing circuits of a sensor and a slave station according to an embodiment of the present invention and their connections.

FIG. 2 is a diagram showing an output state by a combination of a control signal and a self-diagnosis signal.

FIG. 3 is a diagram showing ON and OFF of a self-diagnosis signal corresponding to a voltage level at an output terminal.

FIG. 4 is a diagram showing wiring of a signal input / output system.

FIG. 5 is a diagram showing circuits of a conventional sensor and a slave station and their connections.

[Explanation of symbols]

3 slave stations 4 sensors I1 Condition circuit I2 output circuit G1 to G3 gate circuit T1 to T4 transistors Vcc1 and Vcc2 power supply terminals OUT1 output terminal GND1, GND2 Ground terminal IN1 input terminal P1, P2 photo coupler C1, C2 comparator

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G05B 23/00-23/02 G06B 19/04-19/05 H04L 13/00

Claims (4)

(57) [Claims] To 1. A signal input device, the power line, a signal output device connected via a cable with a ground line and signal lines, output provided to a single output terminal connected to the signal line
Force signal, the voltage of which tries to transmit to the signal input device
For each state in at least two signals
According to the combination of information to be divided into a predetermined number of levels
And the combination from the output terminal only.
A signal output device that outputs a voltage signal corresponding to the combination . 2. An attempt to transmit to the signal input device 2
The signal output device according to claim 1, wherein one of the two signals is a control signal and the other is a self-diagnosis signal of the device. Wherein the output terminal of the signal output device according to claim 1 or 2, an input terminal connected through the signal lines of the cable, the input terminal from the output terminal
A first operating element and a second operating element for operating according to the respective states of the at least two signals by a signal transmitted to the first and second operating elements, and a circuit operating each of the two operating elements, wherein the circuit outputs the output signal. A signal input device having a voltage region in which both of the operating elements are operated and a voltage region in which they are not operated with respect to a level of a voltage applied from a terminal to the input terminal. 4. A signal output device according to claim 1 or 2, and a signal input device of claim 3, wherein the output terminal of the signal output device and said input terminal of said signal input device Is connected via the signal line of the cable, and a signal input / output system between devices.