JPS5819617Y2 - Signal output unit - Google Patents

Description

[Detailed explanation of the invention] This invention is based on the on/off signal output from the arithmetic processing unit, etc.
This relates to a signal output circuit in which a signal output circuit that outputs a signal to the outside by activating a switching element when the user forgets to do so is operated by a power supply supplied from the outside.
The purpose of this is to detect that the voltage of the power supply supplied from the outside has fallen below a predetermined value and turn on the error lamp, so that when an error occurs, it is easy to identify the cause of the error. In addition to making it possible to distinguish between the two, the addition of an anomaly detection circuit prevents external noise signals from passing through the anomaly detection circuit and entering the arithmetic processing unit, and also simplifies the circuit and reduces power consumption. There is a particular thing.

Press the button on the signal output unit that outputs a signal to the outside based on the on/off signal output from the arithmetic processing unit of a general sequence controller, transfers data to an external device, or energizes or deenergizes an external load. is equipped with photo-isolation consisting of a light-emitting diode, a phototransistor, etc. to prevent noise signals generated from external equipment from entering the processing unit, and the switching element is activated by the output of the light-receiving element such as the phototransistor. It outputs a signal to the outside.

For this reason, in such an output unit, it is necessary to bring in a power source from outside to operate the light receiving element, and it is necessary to bring in a power source from outside to operate the light receiving element. Power for operating the light receiving element and the switching element is supplied from outside, except for those in which the light receiving element can be operated by the voltage across the connected switching element.

Therefore, in such a signal output crab unit,
Whether the signal output circuit consisting of the light receiving element, switching element, etc. operates normally depends on whether the voltage of the power supply supplied from the outside is higher than the appropriate value. If it falls below an appropriate range, the signal output circuit may malfunction or stop operating at all, and the signal cannot be sent out normally.

In this way, if the signal transmission is not performed normally, the operation of the signal receiving side will not be performed normally, resulting in an abnormal state.However, in the past, it was not possible to check whether the power supply voltage supplied from the outside was normal. Since no detection was performed at all, even if an abnormality occurred due to an abnormality in signal transfer, the signal could not be sent normally due to a drop in the voltage supplied from the outside. It was not possible to determine whether the signal was not being sent normally due to a malfunction, and it took time to determine the cause of the abnormality.

In particular, if the power supply supplied from the outside temporarily drops and an abnormality occurs in signal transfer, it is normal to measure the voltage of the power supply supplied from the outside with a tester after the abnormality occurs. It was impossible to determine that the cause of the signal transfer abnormality was a voltage drop in the externally supplied power supply.

The present invention eliminates these conventional drawbacks, and also reduces the power consumption of the light emitting element that constitutes the photocoupler that prevents the intrusion of noise signals. In addition to providing a capacitor that is charged by a power source, by comparing the potential of this capacitor with the potential of an external power source, a drop in the voltage of the power source supplied from the outside is detected, and the light emitting element that constitutes the photocoupler is lit accordingly. It is characterized by its strong character.

Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, 10 is an arithmetic processing unit such as a sequence controller, 11 is a signal output unit, and 12 is a numerical controller. The signal output unit 11 is provided with a plurality of signal output terminals DO1 to DOn that output signals to the outside. However, these output terminals DO1 to DOn are connected to the numerical control device 12.
are connected to signal input terminals DII to DIn, respectively.

Further, the signal output unit 11 is provided with an external power terminal PT and a common terminal C0M0 for supplying power to operate the light receiving element, switching transistor, etc. from the outside, and these terminals are connected to the numerical control device 12. It is connected to the side power output terminal POT and the ground terminal ET.

As shown in FIG. 2, this signal output circuit 11 is connected to a latch circuit 20 that latches and outputs a plurality of on/off signals output from the arithmetic processing device 10, and output terminals Q1 to Qn of this latch circuit 20. The light emitting diodes PD1 to PD are activated by the on/off signal output from the latch circuit 20.
Inverter I NV 1 to I that blinks each n
A phototransistor PTR that is optically coupled to NV n and each of the light emitting diodes PD1 to PDn and is turned on when the light emitting diodes PD1 to PDn are turned on.
1 to PTRn and the phototransistors PTR1 to PTRn.
It is mainly composed of switching transistors 5TR1 to 5TRn that are turned on and off by the output of TRn.

And switching transistors 5TR1 to 5TRn
A phototransistor PTR that forms a signal output circuit together with
1 to collector rr-1 of PTRn, each resistor R21 to
It is connected to the external power supply terminal PT via R2n, and its emitter is connected to the bases of switching transistors 5TR1 to RTRn connected between each of the signal output terminals DO1 to DOn and the common output terminal C0M0.

Moreover, phototransistors PTRI~
Switching transistor 5 due to dark current of PTRn
A resistor R that prevents TR1 to TRn from turning on.
31 to R3n are connected.

Therefore, when a predetermined one of the phototransistors PTR1 to PTRn is turned on due to lighting of the light emitting diodes PD1 to PDn, the resistors R21 to R2nR31 to A current determined by R3n and the power supply ■0 supplied from the outside flows, and if the voltage of the power supply vO is thicker than a predetermined value, the switching transistor STR becomes saturated, and a predetermined signal output from the signal output terminals DO1 to DOn is output. The terminals are electrically connected to the common output terminal to transmit signals.

However, if the voltage of the externally supplied power supply VO falls below the allowable range, the switching transistor STR may not be completely turned on even if the phototransistor PTR turns on. In this case, the signal transmission will not be carried out normally and the numerical control device 12 will malfunction.

The voltage drop detection circuit 21 is provided to determine, when such an abnormality occurs, whether the cause of the abnormality is due to a voltage drop in the power supply supplied from the outside. A given power supply VO is input, and when the voltage of the power supply VO falls below a predetermined value, this is stored as an abnormality and an abnormality lamp PTAB is turned on.

As shown in FIG. 3, this voltage drop detection circuit 21 includes a capacitor 01 connected between an external power supply terminal PT and a common output terminal C0M0 via a backflow prevention diode D1 and a resistor R3, and this capacitor C1. The charging voltage of the transistor TR1 is compared with the external power supply voltage applied to the external power supply terminal PT, and when the difference therebetween becomes equal to or higher than the operating voltage of the Zener diode ZD, the transistor TR1 constitutes a switching circuit and turns on. When turned on, a light emitting diode PD20 emits light due to the charge charged in the capacitor C1, and the anode is connected to the resistor R5 and the abnormal lamp P.
A photothyristor PSCR constitutes a latch circuit that is connected to the internal power supply Vi of the processing unit 10 via the LAB and is turned on by light emission from the light emitting diode PD20, and a reset signal R8T when the processing unit 10 starts operating.
and a transistor TR2 which resets the self-holding of the photothyristor pscRD.

Therefore, while the voltage of the power supply Vo supplied from the outside is at a normal value, the photothyristor PSCR1 is in a non-conducting state and the abnormality lamp PLAB is not lit. When the voltage decreases beyond the allowable value determined by the Zener diode ZD, the transistor TR1 becomes conductive, the light emitting diode PD20 lights up, and the photothyristor PSC1'W; turns on, so the abnormality lamp PLAB is lit.

After this, even if the voltage of the externally supplied power source Vo returns to its original state, the photothyristor PSCR remains on, so the abnormality lamp PLAB does not go out.

Therefore, even if an abnormality occurs due to a constant drop in the voltage supplied from the outside and signals are no longer transferred normally, it can be determined that the cause is a drop in the external power supply.

Further, as shown in FIG. 4, an abnormality signal ABS may be generated when a decrease in electric power is detected, and the operation of the arithmetic processing unit 10 may be stopped by this abnormality signal ABS.

In this way, it is possible to prevent the control from being continued in a state where the signal transmission is not performed normally, and it is possible to prevent the occurrence of an abnormality.

As described above, in the present invention, a capacitor that is charged by an external power supply is provided inside the signal output unit, and the voltage of the power supply supplied from the outside is lowered to a predetermined level with respect to the charging potential of this capacitor. At the same time, the light is turned on by the charged charge of the capacitor, which is a light emitting element that makes up the photocoupler, and the light emitted from this light emitting element activates a latch circuit that is operated by the power supply on the processing unit side, so that the abnormal lamp is turned on. In addition to being able to reliably detect voltage drop or loss of external power supply,
Even if such a detection circuit is provided, there is an advantage that noise signals can be prevented from entering from the outside.

Additionally, this device detects voltage drops in the external power supply by comparing the potential of the capacitor charged by the external power supply with the external power supply, so voltage drops can be detected without the need for a special reference power supply. In addition to simplifying the circuit, the light-emitting element lights up only when the voltage of the external power supply drops, so no current flows to the light-emitting element while the external power supply is normal, which has the advantage of reducing power consumption. .

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 shows a connection between an arithmetic processing unit and a numerical control device via a signal output unit, and FIG. 2 shows a specific example of the signal output unit 11 in FIG. 3 is an electric circuit diagram showing a specific configuration of the voltage drop detection circuit 21 in FIG. 2; FIG. 4 is an electric circuit diagram showing a second embodiment of the voltage drop detection circuit 21. It is. DESCRIPTION OF SYMBOLS 10... Arithmetic processing unit, 11... Signal output unit, 12... Numerical control device, 20... Latch circuit, 2
1...Voltage drop detection circuit, PD1-PDn...Light emitting diode, PLAB...Abnormal lamp, PT...External power supply terminal, PTR1-PTRn...Phototransistor, STR...Switching transistor.

Claims (1)

[Scope of utility model registration request] In a signal output circuit that operates a signal output circuit that outputs a signal to the outside by operating a switching element in response to an on/off signal output from a signal output source such as an arithmetic processing unit, the signal output circuit is operated by a power supply supplied from the outside. A capacitor is connected to a pair of terminals to which power is supplied from the outside, and a reverse flow prevention diode is connected between the capacitor and the pair of terminals to prevent the electric charge of the capacitor from flowing to the outside, and further, a switch circuit that is activated by the voltage charged in the capacitor and lights up a light emitting element by the charge of the capacitor when a voltage supplied from the outside is lower than the voltage of the capacitor by more than a predetermined value; A signal output crab knit characterized by being provided with a latch circuit that is operated by a power source, is optically coupled to the light emitting element, and remembers that the light emitting element has been lit, and lights up an abnormal lamp.