JPH064114A - Programmable controller - Google Patents

Abstract

(57) [Abstract] [Purpose] To allow a programmable controller to easily connect a plurality of input devices with different input current levels. [Configuration] Input terminals 50a, 50 to which input devices are connected
A plurality of resistors having different resistance values are connected in parallel to the base of the transistor 5 which supplies a current between b, and a combination of resistors designated by the digital data latched by the data latch circuit 8 is used as a base resistor. The digital data of the data latch circuit 8 is set for each input in a memory provided separately, and the collector current of the transistor 5 is changed by rewriting the data in this memory according to the specifications of the input device. Change.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a programmable controller, and more particularly to a programmable controller suitable for installation at a site where there are a plurality of current levels of various inputs taken from a controlled object.

[0002]

2. Description of the Related Art In recent years, programmable controllers have come to be used to control various devices. In addition, as in the past, not only the on / off information of the switch is taken in and the sequence control is performed,
Numerical calculations are being performed by taking in analog data detected by various sensors.

However, in the conventional programmable controller, the input circuit thereof is, for example, Hitachi Programmable Controller System HIZAC D-28 / D-40 / D-64 Application Manual (Printed in Japan YF-TH November 1982). (HT)) Table 6 on page 6
As shown in the "input specification table", the input current is fixed at 7 mA / point and one kind of input current specification. For this reason,
When using a conventional programmable controller,
If the input current at the installation site differs from the manual input specifications, an external additional circuit is required.

FIG. 9 is a general configuration diagram of a programmable controller. The input circuit 50 includes an input terminal 50a,
The on / off information of the switches connected between the terminals 50b is fetched as an electric signal, converted into an optical signal for isolation, and then converted again into an electric signal for control unit 10.
Send to 0. Based on this input signal, the control unit 100 generates a control signal according to the user program programmed by the programming device 101 and stored in the sequence program storage unit 102, and commands the controlled load 104 via the output unit 103. Is sent.

As described above, since the conventional programmable controller has only one input current specification,
As shown in 0, when a current value that does not meet this specification is used, the switch 1 as an input device connected between the input terminals 50a and 50b is connected to the power supply 2 as an external additional circuit, and the input circuit 50 is A sufficient current is secured to detect the input signal.

[0006]

As described above, in recent years, programmable controllers have been installed in various places, and the current specifications of switches and sensors used for capturing input signals have been varied. However, since the input current specification of the conventional programmable controller is one specification, it is necessary to provide an external additional circuit for input as shown in FIG. 9, which causes a problem that the user's burden is increased. Further, as a sensor, TTL or C having a small operating current is used.
There is also a problem that the sensor cannot be used because MOS cannot be used. In addition, when an input device such as a sensor or a switch is changed to an input device having a different specification, an external additional circuit accompanying it must be changed, which is troublesome.

It is an object of the present invention to provide a programmable controller which can be used as an input device even with a sensor having a small operating current and can easily deal with various kinds of input current levels.

[0008]

The above object is to provide an input circuit connected to an input device for taking in information of a controlled object, a control section for executing a sequence program based on an input signal taken in from the input circuit, and An output unit that is connected to the control unit and outputs a control command to a control target based on the execution result of the sequence program; and a storage unit that is connected to the control unit and stores a current value supplied to the input device corresponding to the input device. A current value setting means for setting each current value to be stored in the storage means, an input of which is connected to the storage means, and an output of which is connected to the input device for each of the current values stored in the storage means. This is achieved by providing current generating means for generating a current and supplying it to the corresponding input device.

[0009]

When the current value required by the input device such as a sensor or a switch connected to the input circuit is different, the current value is set and supplied on the programmable controller side for the input device. It is possible to deal with the input device of the specification, and it is possible to apply it to various sites. Further, even when the input device is connected to another input device, the setting can be easily changed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a programmable controller according to an embodiment of the present invention. The input unit 50 according to the present embodiment is provided with the variable current generating unit 3 as a current generating unit for each input. As shown in FIG. 2, the current generated by the variable current generator 3 is applied to the terminal 5
0a, and the input device 1 such as a sensor or a switch is connected between this terminal 50a and the other terminal 50b. The current flowing to the terminal 50b through the input device flows to the ground through the light emitting diode 4a of the optical coupler 4 as an input circuit. Light receiving transistor 4b of optical coupler 4
Converts the light from the light emitting diode 4a into an electric signal and sends it to the control unit as an input signal.

The variable current generator 3 includes a transistor 5 and
It includes base resistors 7a, 7b, 7c, 7d and a latch circuit 8. The transistor 5 has a collector connected to the power supply + V and an emitter connected to the terminal 50a. The base of the transistor 5 has four base resistors 7a, 7b,
7c and 7d are connected in parallel. When the resistance value of the resistor 7a is R, the resistance values of the resistors 7b, 7c, and 7d are
They are R / 2, R / 4 and R / 8, respectively.

The latch circuit 8 is a data latch circuit 8 for latching 4-bit data in this embodiment, and the output line corresponding to each bit of the latch circuit 8 is connected to the corresponding four base resistors 7a to 7d. ing. The latch circuit 8 is connected to the memory 11 via the data line 9 and is connected to the address decoder 12 via the chip select line 10. When this latch circuit is selected by the address decoder 12, the 4-bit data in the memory 11 is transferred to the data line 9
Is supplied to the latch circuit 8. Then, the combination of the base resistors to be used is determined for the 4-bit data, and the determined base resistors are connected to the base power supply. As a result, the base current Ib of the transistor 5 has a current value of 15 V / R steps from Ib = 0 to Ib = 15 V / R, where V is the voltage of the output line.
It can be made variable in stages (excluding Ib = 0).
Therefore, the collector current of the transistor 5 can be set in 15 steps.

FIG. 3 is a block diagram of the essential parts of an input circuit having 16 inputs. Each latch circuit 8 of the variable current generator 3 having the configuration of FIG. 2 corresponding to each input is connected to the memory 11 via the data line 9 and to the address decoder 12 via the chip select line 10.

FIG. 4 is a conceptual diagram of the connection between the memory 11 and each latch circuit 8. The memory 11 is provided with areas corresponding to the respective latch circuits 8 and is stored in each area.
The bit data is transferred to the corresponding data latch circuit 8 through the data line 9.

When the user sets or changes the input device connected to the input circuit 50, the input current level is input as an analog numerical value through the program device 101 as the current value setting means. This analog numerical value is converted into a digital value used internally by the sequencer according to the data conversion characteristic shown in FIG. 5 (for example, the maximum current value determined by hardware corresponds to (1,1,1,1)). Is
It is stored as 4-bit data in the area corresponding to the input circuit in the memory 11. In the case of changing the input device, the changed input current level is similarly converted into a digital value and overwritten on the previous data. As a result, as shown in FIG. 6, correspondence between software data and hardware data is obtained.

When using such a programmable controller, the address decoder 12 outputs a data address corresponding to each input terminal to the memory 11 and outputs a chip selector signal to each data latch circuit 8 in response to a command from the control unit 100. . As a result, each 4-bit data read from each area of the memory 11 is transferred to the corresponding data latch circuit 8, and each base resistance is determined. As a result, input devices 1 with different current levels
It becomes possible to connect to one programmable controller.

In the above-mentioned embodiment, it is possible to set the current level in 16 steps (actually 15 steps) using 4-bit data. When a current level of more than 16 levels is required, a voltage control circuit 13 is provided between the data latch circuit 8 and the resistor 7 as shown in FIG. 7, so that other configurations are not changed. Can be dealt with. For example, when 16 × 3 kinds of current levels are required, the voltage control circuit 13 divides the input voltage V and outputs it as V / 16, and a circuit that outputs it as V as it is. A circuit for boosting and outputting as 16 V may be prepared. These respective circuits may be collectively prepared as one voltage control circuit 13, or each circuit may be separately prepared and applied to each current generator 3 (FIG. 2). In this way, by preparing a circuit capable of varying the output voltage with respect to the input voltage V, the base current Ib of the transistor 5 is stepped by V / 16 from Ib = 0 to 15V / 16, and Ib = 0 to 15V / 15V / R step to R, Ib
It is possible to set the input current level in a wider range or in a finer manner, such as 16V / R steps from = 0 to 240V / R.

FIG. 8 is a block diagram of a variable current generator according to the second embodiment of the present invention. The variable current generator of this embodiment is configured to change the base bias voltage by the OP amplifier 15 without using a resistor. The data of the data latch circuit 8 is converted into an analog value by the A / D converter 14 and applied to the OP amplifier 15, so that the base bias voltage of the transistor 5 is changed.

FIG. 9 is a block diagram of a variable current generator according to the third embodiment of the present invention. In this embodiment, the four resistors 7
a, 7b, 7c, 7d are switched by the changeover switch 16 to make the base current of the transistor 5 variable.

[0020]

According to the present invention, even if there are a plurality of input devices having different current levels at the installation site, it can be easily dealt with only by software, and the application range of the programmable controller is widened. is there. There is also an effect that the device configuration can be made inexpensive.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a programmable controller according to an embodiment of the present invention.

FIG. 2 is a main part configuration diagram of an input of the input circuit 1 of the programmable controller according to the present embodiment.

FIG. 3 is a main part configuration diagram of a programmable controller having 16 inputs.

FIG. 4 is an explanatory diagram of data transfer of a memory and a data latch circuit.

FIG. 5 is a data conversion characteristic diagram.

FIG. 6 is an explanatory diagram of conversion between software data and hardware data.

FIG. 7 is a main part configuration diagram of an embodiment in which a voltage control circuit is provided.

FIG. 8 is a configuration diagram of a variable current generator according to a second embodiment of the present invention.

FIG. 9 is a configuration diagram of a variable current generator according to a third embodiment of the present invention.

FIG. 10 is a connection diagram of a conventional input device.

[Explanation of symbols]

1 ... Input device, 3 ... Current generating means, 4 ... Input circuit, 5 ...
Transistors, 7a to 7d ... Resistors, 8 ... Data latch circuits, 9 ... Data lines, 10 ... Chip select lines, 11 ... Storage means, 12 ... Address decoder, 50 ... Input section, 50
a, 50b ... Input terminal, 100 ... Control section, 101 ... Current value setting means, 103 ... Output section.

Claims (1)

[Claims] 1. An input circuit connected to an input device for fetching information to be controlled, a control section for executing a sequence program based on an input signal fetched from the input circuit, and the sequence program connected to the control section. An output unit that outputs a control command to a controlled object based on an execution result, a storage unit that is connected to the control unit and stores a current value supplied to the input device corresponding to the input device, and each storing unit that stores the current value. Current value setting means for setting the current value,
An input connected to the storage means and an output connected to the input device to generate a current of each current value stored in the storage means and supply the current to a corresponding input device. Characteristic programmable controller.