JPH0656400B2 - Contact information detection unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to contact information detection for directly connecting to an object to be detected and detecting the on / off state of a control relay contact or the on / off state of an I / O of a sequencer. Regarding the unit.

[Conventional technology]

Control relay contact on / off status, sequencer I / O
In the case of detecting the ON / OFF state of O, a similar relay is added in the former case, and in the latter case, I / O allocation is increased.

[Problems to be solved by the invention]

However, due to the lack of empty space in the control panel and the limited number of I / O spares in the sequencer in many cases, it may not be possible to detect the desired amount of contact information. There was a problem that long downtime could affect production.

The present invention has been made in view of the above circumstances, and is resistant to surges and chattering that occur in contacts, does not affect the circuit to be detected, and further improves the length of the lead wire connected for detection. It is an object of the present invention to provide a contact information detection unit whose detection performance is not affected.

[Means for solving problems]

The contact information detection unit according to claim 1 which is in line with the above object, is connected to the surge absorption circuit, which is provided on the input side and absorbs a surge from a circuit to be detected in which a contact to be detected is present. It has an impedance measuring circuit for measuring the change in impedance when the contact is turned on and off through the surge absorbing circuit, and moreover, the impedance measuring circuit is composed of a bridge circuit, and measures the current during bridge operation. It is configured to detect and output by a photo coupler.

[Action]

In the contact information detection unit according to the first aspect, the surge information is directly connected to the contact to be measured and the surge received from the contact is absorbed by the surge absorbing circuit. Since the bridge circuit is used for the impedance measuring circuit of the contact to be measured, the bridge circuit is balanced in advance with the contact turned on (or off). Then, when the contact is turned off (or on), the impedance of the circuit changes and the balance of the bridge circuit is lost. Therefore, by detecting this, the contact state can be detected.

〔Example〕

Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.

Here, FIG. 1 is a circuit diagram of a contact information detection unit according to an embodiment of the present invention, and FIG. 2 is an overall configuration diagram of a contact information detection device using the contact information detection unit, FIG. 3, FIG.
The figure is a schematic block diagram of a contact information detection device that has been further systematized.

As shown in FIG. 1, a contact information detection unit 10 according to an embodiment of the present invention includes a surge absorption circuit 11 connected to a contact to be detected, a bridge circuit 12 which is an example of an impedance measurement circuit, And a power supply circuit 13. These will be described in detail below.

The surge absorbing circuit 11 includes capacitors 14, 15 and a resistor 16 that absorb a surge generated between the ground, a varistor 18 that clamps a surge between lines, and a resistor 17 that consumes a surge current. The surge of about 2000 V and about 200 msec generated when the contacts are opened and closed is absorbed. It should be noted that the capacitors 14 and 15 are arranged so as not to affect the operation of the detected circuit.
For the varistor 18, use the one that is open at the time of burst, and the varistor 18 that has a fuse so that the circuit to be detected is equivalently turned on by the short circuit of this surge absorption circuit even though the circuit to be detected is open. To prevent.

On the other hand, the bridge circuit 12 includes resistors 19, 20, 21 and a variable resistor 22 that form a bridge, a diode 23, a transistor 24 connected in series to the circuit to be measured, and a bias resistor 2 for the transistor 24.
5, 26, a speed-up condenser 27a, and a surge absorbing condenser 27. A photo coupler 2 is provided on the output side of the bridge circuit.
8 is connected, and when the variable resistor 22 is adjusted and the bridge circuit 12 is balanced with the contact 29 to be measured closed, the current flows to the photocoupler 28 when the contact 29 opens. , Is designed to generate a signal on its output side.

The power supply circuit 13 has a well-known structure, rectifies an AC voltage stepped down by a transformer (not shown) by a diode bridge 30, and passes a predetermined DC voltage through a three-terminal regulator 31, low-voltage power supply elements, and smoothing capacitors 32, 33. A voltage is supplied to the bridge circuit 12.

Therefore, when the contact information detection unit 10 is used, the contact (for example, the contact 29) to be measured is connected to the measurement terminals 34 and 35 by the lead wire, and the terminal 36 is grounded. In this case, when the circuit is a DC circuit, the measurement terminal 34 side is connected to the plus side. Then, the variable resistor 22 is adjusted with the contacts closed to balance the bridge circuit 12 and prevent current from flowing to the photocoupler 28. In this embodiment, the adjustment of the bridge circuit 12 is performed by the variable resistor 22. However, when the circuit to be detected has a contact, the resistance seen from the bridge is roughly the length of the lead wire or the contact is rough. Since it is 100 Ω or less, if the variable resistor 22 is set in advance so as to be balanced with this, no adjustment is usually required on site.

When the contact 29 is closed, the diode 23, the resistor 1
7, current flows through the contact 29 and the transistor 24, the bridge circuit 12 is balanced and no current flows through the photocoupler 28, but when the contact 29 is opened, the bridge circuit 1
The balance of 2 is lost and a current flows through the photocoupler 28, so that a signal that becomes conductive is generated on the secondary side thereof.

Here, in the case where the circuit to be detected is an alternating current circuit, when a negative half wave of alternating current is applied to the measurement terminals 34 and 35, the current is bypassed through the transistor 24 and the diode bridge 30. 12 is not affected. Therefore, even in such a case, when the contact 29 is opened, the photocoupler 28 operates to detect the opening of the contact 29.

Further, even if a normal mode surge voltage (2000 V, 200 msec) is generated at both ends of the relay contact 29, the varistor 18 clamps it to prevent the surge from entering. At this time, a short circuit due to deterioration of the varistor 18 is protected by a protective fuse (not shown). It has also been theoretically and experimentally proved that the arc voltage across the contacts is clamped and the arc bridging between the contacts lasts longer and is longer than the original degaussing time. The device is not affected by providing the resistor 17.

Similarly, if only the contact of 29a is opened while the other contacts are closed while the contact 29 shown in FIG. 1 is open / closed, the common mode surge voltage is applied across the contact 29 from the control relay which is the load. Occurs, and the size is, for example, 200
Although it is 0 V and 200 msec or more, this surge voltage escapes to the ground through the bypass capacitors 14 and 15 and is clamped below the withstand voltage of the constituent elements to prevent surge intrusion.

FIG. 2 shows a contact information detection device 37 provided with eight such units 10 (indicated as faulty contact detection circuits 1 to 8 in the drawing), each from a photo coupler 28 of the unit. Are output to the digital delay circuit 38 in an insulated state. This digital delay circuit 38
The signal delay time is controlled by the delay time setting section 39 by, for example, chattering that occurs when the contacts are opened,
It is possible to give a signal a delay time that does not detect chatter and the like.

Then, the signal delayed for a certain period of time is input to the first latch circuit 40, the first input signal is latched by the circuit, and the output is amplified by the output drive circuit 41 and then is formed by a light emitting diode. Display unit 4
2 is driven or a fast latch output, an alarm output, a contact information output, and a prohibition output are generated.

FIG. 3 shows an example in which the contact information detection device 37 according to the above-mentioned embodiment is systemized. As shown in FIG.
Information is input to the contact information detection device 43 that can detect 8 × 4 contacts, and the contact information from these is subjected to time discrimination (digital filtering), fast latching, or the contact opening / closing information as it is. Input to and take out from a general recorder 44 such as a memory hi-coder, and further, using a telephone line 45, a remote personal computer 4
6, and the signal processing is appropriately performed to monitor the contact information from a remote place.

Further, in FIG. 4, the signal of the contact information detection device 43 is further logged and saved in the IC card. And this IC
The card can be taken out and the data can be sucked up to the personal computer by the IC card read / write unit 48 at a distance, and further the logging data can be sucked up online via the public line.

With these devices, contact opening / closing information can be directly extracted from the detection target, logged in large quantities, and subjected to failure analysis immediately or carefully.

〔The invention's effect〕

As is apparent from the above description, the contact information detection unit according to claim 1 is connected to an I / O of a control panel or a sequencer, and the control system can be a direct current or an alternating current. Even if a surge voltage is generated from the detection circuit, it is possible to prevent the surge voltage from entering and detect the open / closed state of the contact.

Further, in the contact information detection unit, the impedance measuring circuit is composed of a bridge circuit and is output by the photocoupler, so that a fine change in impedance can be detected, there is no malfunction, adjustment is easy, and the function of a large number of contacts is provided. Can be detected independently without affecting the.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a contact information detection unit according to an embodiment of the present invention, FIG. 2 is an overall configuration diagram of a contact information detection device using the contact information detection unit, and FIGS. It is a schematic block diagram of a contact information detection device that has been upgraded. [Explanation of reference symbols] 10 ... Contact information detection unit, 11 ... Surge absorbing circuit, 12 ... Bridge circuit, 13 ... Power supply circuit, 14,
15 ... condenser, 16, 17 ... resistance, 18 ...
Varistor, 19-21 ... Resistance, 22 ... Variable resistance,
23 ... diode, 24 ... transistor, 25,
26 ... Bias resistor, 27 ... Surge absorbing capacitor, 27a ... Speed-up capacitor, 28 ...
... Photo coupler, 29 ... Contact, 30 ... Diode bridge, 31 ... 3-terminal regulator, 32, 33
...... Smoothing capacitors, 34, 35 …… Measurement terminals, 36
...... Terminal, 37 ...... Contact information detection device, 38 ...... Digital delay circuit, 39 ...... Delay time setting circuit, 40 ...... First latch circuit, 41 ...... Output drive circuit, 42 ...... Display section, 43 ...... Contact information detection device, 44 ... recorder, 45 ... telephone line, 46 ... personal computer, 47 ... I
C card recorder, 48 ... IC card read / write unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsushi Fukada 2753-5 Nakahara, Kasuya-cho, Kasuya-gun, Fukuoka Prefecture (56) References: JP 56-12560 (JP, A)

Claims (1)

[Claims] 1. A surge absorbing circuit provided on the input side for absorbing a surge from a detected circuit in which a contact to be detected is present, and a change in impedance when the contact is turned on and off, connected to the surge absorbing circuit. And an impedance measuring circuit for measuring through the surge absorbing circuit, and the impedance measuring circuit is composed of a bridge circuit, and detects the current at the time of the bridge operation by the photocoupler and outputs it. Characteristic contact information detection unit.