JPS625404A - Signal level converter - Google Patents

Abstract

PURPOSE:To prevent noise from being induced in a weak electric system due to the large current of a strong electric system by permitting a photoisolator, etc., to separate electrically the signals of the weak- and strong-electric systems. CONSTITUTION:The photoisolator 14 is composed of a photocoupler where an LED faces a photodiode or a phototransistor, and an amplifier amplifying the output of the coupler, and its input and output sides are electrically insulated. When the LED is driven by a control signal CS, a signal equivalent to the signal CS can be obtained at the output side of the isolator 14. The noise induction due to a large current can be prevented in a weak electric interface 2 to which a signal level converter 7 is connected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a signal level conversion device suitable for application to a control device for a motor that rotationally drives a rolling roll or the like.

[Prior art] When connecting an external control target to a control computer,
When the object to be controlled is a weak electric system device such as an electronic circuit control device, a configuration as shown in FIG. 5 is adopted. In the figure, ■ is a computer (hereinafter referred to as CPU), 2 is a low power interface, and the controlled object 3 is connected to CPtJl via the low power interface 2.

On the other hand, in a system in which a CPU controls a heavy electric system device such as a motor, as shown in FIG.
must be connected.

Here, the light current interface 2 handles a control signal voltage level of 5V to 48V DC, and the high power interface 4 handles a control signal voltage level of 100 to 22V AC.
Handle 0V.

[Problems to be Solved by the Invention] Incidentally, in the device shown in FIG. 6, since a large current flows through the high-power interface 4, noise may be induced in the low-power interface 2 and the CPU, causing malfunctions. was there. For this reason, it was necessary to take measures on the circuit as a countermeasure against noise and to consider the wiring route. Furthermore, a large space is required to house the high-power interface 4, which causes the control device to become large.

The present invention was made against this background, and it is an object of the present invention to provide a signal level conversion device that has excellent noise resistance and allows for miniaturization of a control device.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a signal level system having an insulating circuit means such as a photo isolator and a low power system transmission line between a low power system and a strong power system. It is characterized by being connected by a conversion device.

[Function] According to the above configuration, since signals between the weak electric system device and the heavy electric system controlled object are exchanged via the insulating circuit means,
The weak electric system device and the heavy electric system controlled object are electrically separated, and it is possible to avoid problems such as noise being induced in the weak electric system device by a signal flowing through the strong electric system controlled object.

In addition, this signal level converter is connected to low-power devices through a transmission line that transmits low-power signals, and has the function of driving heavy-power devices in the same way as conventional heavy-power interfaces. There is no need to store a high-power interface inside the device, and it is possible to miniaturize low-power devices.

Furthermore, by installing the signal level converter near the strong electric system equipment, there is no need to run the strong electric system wiring all the way to the weak electric system equipment, so it is possible to reduce costs.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an output signal level converter 7 according to a first embodiment of the present invention, and as shown in FIG. connected between the system controlled object 5 and the C
A heavy electrical system control object 5 such as a motor is controlled by a control signal from the PUI. Also, Figure 3 shows
1 is a perspective view showing the external configuration of a signal level converter 7. FIG.

In these figures, 11 is the low power interface 2
and the input side connector 12 of the signal level converter 7. Through this transmission line 11, the CPU
A control signal C9 (for example, 16 bits) from the signal level converter 7 is supplied to the signal level converter 7. This control signal C8 is supplied to the status display i3 and displayed on the status display 13 bit by bit, and is also supplied to the photo-isolator 14.

The photo-isolator 14 is composed of a photo-coupler in which an LED (light-emitting diode) and a photodiode or a photo-transistor are opposed to each other, and an amplifier that amplifies the output of this photo-coupler, and the input side and the output side are electrically connected. is insulated. Then, when the LED is driven by the control signal C8, the photoisolator 1
A signal equivalent to the control signal C5 is obtained on the output side of the control signal C5.

The output signal of the photo isolator 14 is a transistor,
It is supplied to the control end of a driver 15 made of a triac or a relay, and the output of the driver 15 is sent to a terminal block 17 via a protection circuit 16. Here, the protection circuit 16
is composed of diodes, capacitors, resistors, etc., and the driver 1 is
This is to prevent 5 from being destroyed. Also,
The terminal block 17 has screws for fixing crimp terminals and the like, and is connected to the drive line of the controlled object 5.

According to such a configuration, only a small current flows through the low current interface 2 to which the signal level converter 7 is connected, so noise caused by large current is not induced in the CPUI or the low current interface 2. This prevents these malfunctions. Furthermore, since the signal level converter 7 is connected to the low-power system device through the transmission line 11, there is no need to house it in the low-power system device.

Therefore, it is possible to downsize the weak electric system device.

Next, FIG. 2 is a block diagram showing the configuration of a signal level conversion device 8 according to a second embodiment of the present invention. As shown in FIG. 4, this signal level converter 8 converts the level of the signal output from the heavy electric system controlled object 5, for example, the alternating current signal output from the auxiliary contact of an electromagnetic contactor or the limit switch, and CP via interface 2
This is a signal level converter for input to U1.

In FIG. 2, parts corresponding to those in FIG. 1 are given the same reference numerals, and their explanations will be omitted. In the figure, an AC signal output from a heavy electrical system controlled object 5 is supplied to a filter 21 via a terminal block 17. This filter 2I is 50
It is a bandpass filter that extracts only Hz or 60Hz AC signals, and its output is sent to the input circuit 23 through the protection circuit 22. The input circuit 23 rectifies the supplied AC signal and then reduces the voltage to form a signal.
This signal drives the photo-isolator 14. The output of the photo isolator 14 is supplied to the status display 13 and displayed bit by bit.
4, is amplified, and sent to the low power interface 2 through the connector 12 and transmission line 11.

According to such a configuration, after the AC signal output from the strong electric system is electrically isolated by the photo-isolator 14 and converted into a low-level signal, this low-level signal is transmitted to the output circuit 24, the connector 12, and the Since the signal is sent to the weak current interface 2 through the transmission line 11, the weak current system and the strong current system are electrically separated, and it is possible to prevent noise from being induced in the weak current system by the large current in the strong current system.

Furthermore, the signal level converter according to each of the embodiments described above is connected to the vicinity of the CPU 1 by the transmission path 11 that transmits the low-power signals, and can be installed near the high-power system. There is no need to turn it over, reducing the cost of the entire system. Also, C.P.
It is possible to significantly reduce the area occupied by the device around U1.

Furthermore, since the status indicator 13 is provided, it is possible to confirm at a glance whether each signal is on or off, and since the terminal block 17 is provided, it is possible to connect thick wiring directly to the signal level converter. .

[Effects of the Invention] As explained above, the present invention electrically separates the signals of the weak electric system and the strong electric system by using an insulating circuit means (for example, a photo isolator), so that a large current in the strong electric system can cause a signal to be transmitted to the weak electric system. It is possible to prevent noise from being induced.

Furthermore, since the signal level converter according to the present invention can be installed at any location, the area occupied by the installation location around the CPU can be halved.

Furthermore, it is no longer necessary to provide a circuit means for noise prevention in the weak electrical system device or to run strong electrical system wiring to the weak electrical system device, so it is possible to reduce costs.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a first embodiment of the invention, FIG. 2 is a block diagram showing the configuration of a second embodiment of the invention, and FIG. 3 is an external appearance of the signal level conversion device according to the above embodiment. FIG. 4 is a perspective view showing the configuration; FIG. 4 is a block diagram showing an example of use of the signal level converter according to the above embodiment; FIGS.
The figure is a block diagram showing the configuration of a conventional control system. 1...CPU, 2...Low electrical interface, 3...Low electrical system control target, 4...
- Strong electrical interface, 5... Strong electrical system control object, 7... Output signal level converter, 8...
... Input signal level conversion device, 11 ... Transmission line, 13 ... Status indicator (display means), 14
...Photo isolator (insulating circuit means), 1
5...driver (driving means), 17...
・Terminal block, 23... Input circuit (input means), 2
4...Output circuit (output means). Figure 4

Claims (2)

[Claims] (1) In a system in which a high-power device such as a motor is controlled by a low-power device such as a control computer, there is a transmission path for transmitting an output signal from the low-power device and a drive for the high-power device. 1. A signal level converting device comprising: a driving means for transmitting a signal; and an insulating circuit means interposed between an output end of the transmission line and the driving means. (2) In a system in which a heavy electric system device such as a motor is controlled by a low electric system device such as a control computer, an input means for receiving an alternating current signal from the high electric system device, and an input means for receiving an AC signal from the high electric system device and the A signal level conversion device comprising: an output means for sending a signal to a weak electric system device; and an insulating circuit means interposed between the input means and the output means.