JPH0368403B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a dual analog signal output device.

In order to increase the reliability of the analog signal output device, the output circuit is duplicated, and one side is used as the active side.
The other side is set as a standby side, and when the active side fails, switching to the standby side is performed.

As a conventional example of a dual analog signal output device, the one shown in FIG. 1 is common. In other words, the output terminals of the two analog signal output circuits 1 and 2 are connected to a matching circuit 3 having a switching function.
The matching circuit 3 is controlled by the control circuit 5 to supply the output signal of one of the two output circuits to the output line 4. I'm starting to do that. The control circuit 5 monitors the operating state of the active side, and when a failure is detected, operates the matching circuit 3 to switch the output signal supply source to the standby side.

Such a conventional device requires a matching circuit 3 having a switching function, its control circuit 5, and a signal line between them. These circuits include active elements, but in order to improve the reliability of the duplexing device as a whole, it is desirable that the number of circuits containing active elements be as small as possible, and it is also desirable that the number of signal lines be as small as possible. Further, when the analog signal output device is an output section of a process control device, etc., it is desirable that its maintenance can be performed without stopping operation, that is, that online maintenance can be performed. However, in this conventional example, online maintenance of the matching circuit 3 and its control circuit 5 is impossible or extremely difficult. In addition, the output circuit on the standby side must always stand by in a normal state and immediately take over when the active side fails, but in this conventional example, whether the output circuit on the standby side remains in a normal state or on standby is necessary. It was difficult to confirm whether this was the case.

An object of the present invention is to eliminate the need for an active element in a matching circuit for two outputs, eliminate the need for a control signal line for the same, and to switch the output signals of two output circuits using a control system separate from the output circuit. No circuit required, online maintenance possible
Another object of the present invention is to provide a duplex analog signal output circuit that can always confirm the normality of the output circuit on the standby side.

The present invention is a duplex analog signal output device in which the output terminals of two analog signal output circuits driven by respective higher-level devices are connected in parallel to a common output line, and each analog signal output circuit is connected in parallel to a common output line. , a variable output analog signal source, an operating device that operates the output value of this analog signal source according to an output setting value given from a higher-level device, and a comparison between the output setting value and the detected output value of the analog signal source. a comparator that corrects the operation of the operating device so that the difference becomes zero, and transmits the corrected operation output to a higher-level device as an abnormality detection signal; and an effective supply of output from the analog signal source to a common output line. A flip-flop circuit is constructed by a combination of a switch that controls disabling, and a gate that controls the on state of this switch using an output signal, and a similar gate in the other analog signal output circuit. It is equipped with a gate that operates by receiving an output enable signal from the output circuit, and a pull-up power supply that connects the output terminal of this gate to a common potential point through a resistor in the other analog signal output circuit. When the output circuit is removed, the low level signal that was input from the gate of one analog signal output circuit to the gate of the other analog signal output circuit disappears, and instead, the high level signal from the pull-up power supply is input to the gate. This is a duplex analog signal output device characterized in that the signal is inputted.

Hereinafter, the present invention will be explained in detail with reference to Examples. FIG. 2 is a conceptual configuration diagram of an embodiment of the present invention. In FIG. 2, reference numerals 1 and 2 are duplicated analog current output circuits, each of which is formed on a printed circuit board or the like, and can be inserted into and removed from a connector. The output terminals of these output circuits 1 and 2 are connected in parallel to a common output line 4 in a matching circuit 3. Upstream of the matching circuit 3, a backflow prevention diode may be inserted into the output terminal of each output circuit 1, 2 as necessary.

In the output circuit 1, CS1 is a variable output current source, DT1 is a current detector, and SW1 is a changeover switch. These are connected in series to form a current path. Depending on the switching of the switch SW1, the output current of the current source CS1 flows to the output line or is directly bypassed to the common.

M1 is an operating device, and H1 is a comparator. current source
The output value of CS1 is manipulated by manipulator M1. The operating device M1 operates the current source CS1 according to an output setting value given from a higher-level device. The difference between the output setting value and the actual output value is compared by the comparator H1, and the operating device M is adjusted so that the difference becomes zero.
1 operation is corrected. The correction operation signal of the comparator H1 is transmitted to a higher-level device as a signal for abnormality detection.

G1 is a NAND gate whose output signal controls switching of the switch SW1, and an output permission signal from a higher-level device is given as one input signal.

The output circuit 2 also has a completely similar configuration. Between the output circuits 1 and 2, the NAND gates G1 and G2 are connected so that their output signals become the input signals of the other. All of these NAND gates are open.
It is a collector type, and its output terminals are pulled up through resistors in each other's circuits. Such a NAND gate G1,G
2, a flip-flop circuit is formed, and one output of these NAND gates is "H".
In this case, an output signal is generated in such a manner that the other output becomes "L". Therefore, switch SW1, SW
2, when one is connected to the contact A side, the other is connected to the contact B side. That is, when one of the output currents of the output circuits 1 and 2 is supplied to the output line 4, the other is directly bypassed to the common. Therefore, there is no need for any switching mechanism in the circuit 3 for matching the output terminals of the output circuits 1 and 2, and no signal line is required for switching control. In addition, when using a backflow blocking diode, the contacts on the A side of the switches SW1 and SW2 may be directly connected to a common contact, and only the contacts on the B side may be alternately turned on and off.

Abnormality detection signals based on the output signals of the comparators H1 and H2 are monitored in their respective higher-level devices, and the presence or absence of an abnormality is determined. When an abnormality is detected, the output permission signal is canceled.

The operation of the device configured in this way is as follows. Now, the output signals of NAND gates G1 and G2 are "L" and "H", respectively, so that switch SW1 is turned to the A side, and SW2 is turned on.
is input to the B side, the output circuit 1 is on the active side and the output circuit 2 is on the standby side. Comparator H on both the active side and standby side
Based on the output signals of H1 and H2, the presence or absence of an abnormality is monitored by each host device. Both output circuits 1 and 2 are in normal condition,
As a result, both gates are given an "H" level output permission signal from the higher-level device.

If the output circuit 1 on the active side fails in this state, the upper circuit sets the output permission signal to "L" in response to the abnormality detection signal. Then, the state of the flip-flop circuit changes accordingly, and switches SW1 and SW2 switch accordingly.
is switched, the output circuit 2 becomes the active side, and the output circuit 1 becomes the standby side. In this way, when the active side cancels its own output permission signal based on its own abnormality detection results, the active side and the standby side are automatically switched. The standby side is constantly monitored for abnormalities by the higher-level equipment, so if an abnormality is detected, it can be repaired immediately, and the output is changed only after normality is confirmed. This can be done by

When performing online maintenance, the process is as follows. Suppose that the output circuit 1 on the active side is now pulled out from the connector for maintenance.As a result of this pulling out, the "L" level signal that was being applied from the NAND gate G1 to the input terminal of the NAND gate G2 disappears, and instead Since the voltage of the pull-up power supply is applied, the output signal of NAN gate G2 is inverted to "L" and the switch SW is turned on.
Insert 2 into side A. This allows the output circuit 2 to take charge of supplying the output current, so that the output circuit 1 can be maintained during this time. That is, according to the present invention, by combining a flip-flop circuit and a pull-up power supply, on-line maintenance is possible. The circuit that matches the output terminals of the two output circuits is simply a collective connection consisting of only passive elements, so it does not require any special maintenance, and since the control circuit is not separate from the output circuit, maintenance is also required. Not.

Another embodiment of the invention is shown in FIG. FIG. 3 shows an example of a configuration in which the output signal is a voltage, and the output signal source is a variable voltage source, so there is no bypass path for the output signal even in the standby state. The case is similar to that shown in FIG. This device also has similar characteristics to the previously described device.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to the above-described embodiments, and may have various embodiments within the scope of the claims.

[Brief explanation of drawings]

FIG. 1 is a conceptual block diagram of a conventional example, and FIGS. 2 and 3 are conceptual block diagrams of an embodiment of the present invention. 1, 2... Output circuit, 3... Matching circuit, 4
...output line, CS1, CS2...variable current source,
DT1, DT2...Output detector, SW1, SW2...
...Switch, M1, M2...Operator, H1, H2
...Comparator, G1, G2...Nand gate.

[Claims]

1 Detecting an error signal regarding the angular deviation amount, deviation direction, and deviation amount between the unmanned guided vehicle and the guide line, and guiding and controlling the unmanned guided vehicle to automatically travel based on this error signal. In the method for controlling an unmanned guided vehicle, a first detection means detects an angular deviation amount of the unmanned guided vehicle with respect to the guide line, and detects a direction and amount of deviation of the unmanned guided vehicle with respect to the guide line. and reference signal output means that outputs a reference signal that outputs a maximum value when the unmanned guided vehicle is on the guide line and whose output value decreases as the amount of deviation increases. a first zone which is provided separately and in which the unmanned guided vehicle performs centering control based on the output of the second detection means; A second method for controlling the unmanned guided vehicle to automatically return to the direction of the guide line based on the output of the second detection means.
determining which zone the unmanned guided vehicle is in based on the output of the reference signal output means or the output of the second detection means;

Claims (1)

A duplex analog signal output device characterized in that there is no low level signal and instead a high level signal from the pull-up power supply is input to the gate.