JPS6051902A - Driving current controlling system - Google Patents

Abstract

PURPOSE:To reduce a current capacity of a power source for an insulating input circuit by bringing a light emitting element driving current of a photocoupler to electric conduction successively by a bit unit from the power source for an insulating input circuit, at the time of delivery of a signal received in parallel by a word unit. CONSTITUTION:A read command (a) sent from a device side for monitoring a state of an electric power equipment apparatus 7 is sent to a scanning circuit 8 through a photocoupler PC1. The circuit 8 sends an hourly shifted pulse (b) from output lines of 16 pieces corresponding to a word, drives a contact driving circuit 10 through an OR circuit 9 and turns on and off a contact rl3. The pulse (b) is sent to switching circuits 12, 13-, too, and the circuits 12, 13- make a current flow successively to PCs 2, 3 from a power source E' for an insulating input circuit, when contacts rl1, rl2- of the apparatus 7 are on. Also, when the contact rl3 is on, a set pulse (d) is sent to an FF group 16 corresponding to the PCs 2, 3- through a PC14 and a distribution controlling circuit 15 by a signal C. The FF group 16 sends a data corresponding to a state of the contacts rl1, rl2- successively to a monitor device side.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention provides a method for monitoring the status of power equipment such as process control equipment via an isolated input circuit using a photocoupler. This invention relates to a drive current control method that can reduce the current response t'.

(b) Prior Art and Problems FIG. 1 is a block diagram mainly showing a conventional isolated input circuit (interface section).

In the figure, 1 to 3 are photocouplers, 4 is a switch circuit, and 5.6
7 is a constant current drive and protection circuit, 7 is a power equipment, E is a power supply for an isolated input circuit, and rtl and r4 are non-voltage contacts.

In order to monitor the status of power equipment such as process control @ equipment, it is common to use 16 pits t'' 1 word and pit parallel reception.Also, since power equipment uses high voltage, it is common to use a condition monitoring device. An insulated input circuit using a photocoupler is used for the ink face portion of the ink face.The power supply (E in FIG. 1) for driving this photocoupler must be insulated from the power supply for the condition monitoring device. Further, a recommended value for the drive current If to be applied to the light emitting element of the photocoupler is determined for each device based on transfer efficiency characteristics and life deterioration characteristics, and is usually about OmA.

A case in which the state of the power equipment equipment 7 is monitored will be explained using FIG. There are 16 contacts rtbr4... for each device to be monitored, and these contacts are turned on or off depending on the state of the device. When the status of equipment is monitored by the status monitoring device, read commands are issued in order for each equipment whose status is to be monitored so that the current supply from the isolated input circuit power supply E does not overlap. This pulse is input to the switch circuit 4 through the photocoupler 1 to which this reading command is issued, which closes the switch and causes current to flow through the 16 photocouplers 2, 3, etc. of the isolated input circuit power supply E. Make it so that it disappears. At this time, for example, contact rt1゜r
4 is on, constant current drive and protection circuit 5.6
A driving current flows through the light emitting element of the photocoupler 2.3, the example light receiving element becomes conductive, and the state monitoring device shows that the contact rtl + r 12 is turned on. If all 16 contacts are on now,
If the drive current per photocoupler is 10 mA from the power source E for the isolated input (b) path, the driving current is 160 mA. Therefore, the power supply E for the isolated input circuit must have at least this current capacity, which has the drawback of increasing the current capacity and increasing the size.

(e) Object of the Invention In view of the above-mentioned drawbacks, the object of the present invention is to provide a drive current control system which can reduce the current capacity of a power supply for an isolated input circuit and enable miniaturization.

(d) Structure of the Invention In order to achieve all of the above-mentioned objects, the present invention provides an isolated input circuit that transfers word-by-word signals in parallel via a photocoupler. The present invention is characterized in that a control means is provided for sequentially applying an element drive current bit by bit.

(e) Examples of the invention An embodiment of the present invention will be described below with reference to the drawings.

Fig. 2 is a block diagram mainly consisting of an isolated input circuit according to an embodiment of the present invention, Fig. 3 is a time chart of waveforms of each part in Fig. 2, and (A) to (D) are 8 to 6 in Fig. 2. corresponds to the point.

Components in FIG. 2 that have the same functions as those in FIG. 1 are indicated by the same symbols. 8
is a scanning circuit, 9 is an OR circuit, 1o is a contact drive circuit, 11
12 is a constant current drive and protection circuit, 12, 13 is a switch circuit, 14 is a photocoupler, 15 is a distribution control circuit, 16 is 7
Lip 70 tube group (hereinafter referred to as FF), rt3 is a contact point,
E' indicates a power supply for the isolated input circuit.

To explain the operation, when the reading command shown in FIG. , transmits time-shifted pulses as shown in FIG. 3(B). This pulse is sent to the contact drive circuit 10 via the OR circuit 9, and the contact risk is turned on and off as shown in FIG. 3(c). Also, this pulse is transmitted through 16 output lines to 16 switch circuits 12, 13...
When this pulse is applied, the switch circuits 12, 13, . At this time, for example, contact r
When tI + r t2 is on, when the contacts of the switch circuit 12.13 are turned on one after another, a drive current flows through the photocoupler 2.3 and the light receiving element of the photocoupler 2.3 becomes conductive.

Of course, even if all 16 contacts are on, the 16 switches Ir1l are turned on in sequence, and the drive current flows from the isolated input circuit power supply E' to the 16 photocouplers in sequence, and at the same time, one photocoupler is turned on. Only drive current flows. On the other hand, when the contact rtB is on, a light emitting element drive current of the photocoupler 14 flows from the isolated input circuit power supply E' through the constant current drive and protection circuit 11, making the light receiving element conductive and distributing it. From the control circuit 15, the FFs corresponding to the 16 photocouplers are sequentially
Output a set pulse as shown in D). This set pulse turns off 16 contacts (rt+, rt
Figure 3 (E) shows the data according to the state of
Set them sequentially as shown. 16 contacts rtI +
If r t2... is on, 16 pieces are off
is set to a logic level of '1''.

The status monitoring device monitors the status of the equipment to be monitored based on the data set to OFF for these 16 pieces.

The scanning circuit 8 is composed of a counter, an OR circuit 9, a contact drive [91 path 1o, 16 switch circuits 1
2.13... are constructed by the CMO 8, and these are supplied with power from the isolated input circuit power supply E', but the required power is very small.

Therefore, the maximum current simultaneously output from the isolated input circuit power supply E' is the drive current to the photocoupler 14 and one of the 16 photocouplers 2, 3, . . . .

Therefore, the current capacity of the power source E' for the isolated input circuit can be reduced to just the drive current capacity of two photocouplers, and the current capacity is small, allowing for miniaturization.

(f) Effects of the Invention As explained in detail above, according to the present invention, the light emitting element drive current of the photocoupler from the power supply for the isolated input circuit is
Since the current is applied sequentially in bit units, the current capacity t' of the power supply for the insulated input circuit can be made small, which has the effect of making it compact.

[Brief explanation of drawings]

Figure 1 is a block diagram mainly consisting of a conventional isolated input circuit, Figure 2 is a block diagram mainly consisting of an isolated input circuit according to an embodiment of the present invention, and Figure 3 is a time diagram of waveforms of each part of Figure 2. It is a chart. In the figure, 1 to 3.14 are photocouplers, 4, 12 and 13 are switch circuits, 5 and 6.11 are constant current drive and protection circuits,
7 is power equipment, 8 is a scanning circuit, 9 is an OR circuit, 10
is a contact drive circuit, I5 is a distribution control circuit, -- m, 16 is a flip-flop group, E, E' are power supplies for isolated input circuits, r l + + r 1
2. rtl indicates a contact point.

Claims (1)

[Claims] In an isolated input circuit that transfers signals in word units in parallel via a photocoupler, a control means is provided to sequentially supply a light emitting element drive current of the photocoupler from a power source for the isolated input circuit in bit units during signal transfer. A drive current control method characterized by: