JPS6093505A - Analog input device for programmable controller - Google Patents

Abstract

PURPOSE:To make a fast response to variation in analog input regardless of the repetition time of program execution by providing the 2nd register circuit and a comparing circuit in an analog input device. CONSTITUTION:An analog input signal A1 is stored as a digital input signal D1 in the 1st register 5 through an insulating amplifier 3 and an A/D converter 4. Meanwhile, the comparing circuit 6 generates a detection signal IT when the signal D1 exceeds a reference signal D2 set previously in a register 7 by a CPU2, and this signal IT is inputted as an interruption request signal to the CPU2. Further, the CPU2 controls the reference value D2 set in the register 7 to control the generation of the signal IT in optional pattern. Thus, the circuits 6 and 7 are provided to make a fast response to variation in analog input regardless of the repetition time of program execution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an analog input device for a programmable controller that controls the relationship between input and output signals according to a program using a central processing unit.

[Prior art]

A conventional device of this type is shown in FIG.

In Fig. 1, 1 is an analog input device, 2 is a central processing unit (hereinafter abbreviated as CPU), 3 is an isolation amplifier for receiving the analog input signal A1 and separating it from the power supply line of the digital circuit, and 4 is this an analog-to-digital (hereinafter abbreviated as A/D) converter for receiving the output of the isolation amplifier 3 and converting an analog quantity into a digital quantity; 5 ViA/D;
This is the first register for storing the digital signal generated by the converter 4.

Next, the operation will be explained. A processed signal input as an external analog human input signal A1 is sent to an isolation amplifier 3, where the external interface power source and the internal power source connected to the CPU 2 are separated. This insulated signal is converted into a digital signal by the A/D converter 4 and sent to the first register 5.
is memorized.

The CPU 2 is configured to read a digital amount D1 proportional to the analog input signal A1 from the analog input device 1 as appropriate. Next, FIG. 2 shows an example of program processing inside the CPU 2 according to this method. First, in process (1) 11, the digital amount corresponding to the signal DIK after A/D conversion is read. Com. Next, in process (2) 12, if the read digital amount is larger than the predetermined value, interrupt processing (3) is performed.After performing step 13, the next program is read again in process (2) 12. If the digital amount is smaller than the predetermined signal, processing (3) 13 is skipped and the program proceeds to the next program.

Since the conventional analog input device is configured as described above, even when it is desired to output the program processing output P1 that corresponds to a change in the analog input signal A1 as shown in FIG. The output signal is required only after the procedure. Since it is configured to obtain PI',
Since there is a slight delay Δt from the ideal original processing output signal Pl, and this time is due to the repetition period t for program execution, it is possible to obtain a force response quickly to changes in the analog input signal A1. This has the disadvantage that it cannot be followed in systems that require fast response and controllability.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional devices as described above, and a second register circuit and a comparator circuit are provided in the analog input device, so that the input data D1 after A/'I) conversion is By generating a detection signal when a preset reference value is exceeded and applying this as an interrupt processing input to the CPU, it is possible to quickly respond to changes in analog input A1 without taking up the program execution repetition time. The purpose of the present invention is to provide an analog input device for a programmable controller that enables flexible responses.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 4, 6F1 is a comparison circuit that compares two digital input data and outputs the comparison result in bits, and 7 is a second register that stores a target value D2 arbitrarily set by the CPU 2. The subsequent digital signal D2 is inputted as a reference value for comparison in the comparator circuit 6.

In the analog input device 1 of this embodiment having such a configuration, the analog input signal A1 is sent to the first register 5 via the isolation amplifier 3 and the A/D converter 4 as the digital input signal D.
1, and at the same time, the comparator circuit 6 stores this signal D
1 becomes larger than the reference signal D2 set in advance in the second register 7 by the CPU 2, a detection signal IT is generated,
This signal IT is configured to be input as an interrupt request signal to the CPU 2. Upon receiving this interrupt request signal IT, the CPU 2 immediately executes various third processes 13 shown in FIG. 2 as interrupt processing.

Also, since it is possible to set and store any reference value using the second register 7Kricp[Jz program, the fourth
Analog input signal A1 that performs stepwise changes as shown in the figure.
By controlling the reference value D2 set in the second register 7 by the CPO2, it is also possible to control the generation of the interrupt request signal IT to an arbitrary pattern pressure.

Although not shown in the above embodiment, the interrupt request signal from the analog input device 1 according to the present invention can be provided with an on/off switch, etc., and various applications can be easily implemented in which the interrupt request signal is selected as necessary.

〔Effect of the invention〕

As described above, according to the present invention, by providing the analog input device with the detection function that conventionally used the program processing by the CPU 2 to determine whether or not other program processing is necessary,
A great effect can be obtained in that an operation delay caused at the same time as program execution can be reduced to a minimum value by using interrupt processing.

In addition, the target value D2, which is the reference value for processing 2, can be set in the second register 7 in advance, and can be executed in another program as preprocessing, so it is excluded from program processing when an interrupt occurs. This makes it possible to respond to changes in analog input signals with the minimum necessary program processing time.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional analog input device, Fig. 2 is a block diagram showing an example of program processing in a central processing unit, Fig. 3 is an operation explanatory diagram showing how an analog input signal changes, FIG. 4 is a configuration diagram of an analog input device for a programmable fist controller according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Analog input device, 2-... Central processing unit (CPU), 3... Isolation amplifier, 4... A/D converter, 5... First register, 6...・Comparison circuit,
7...Second register, 11...Processing 1.12...
・Processing 2.13...Processing 3 The middle symbol in the figure indicates the same or equivalent part. Agent Masuo Oiwa Figure 1 Figure 4 Figure 2 Figure 3 Δ1

Claims (1)

[Claims] In an analog input device for a programmable controller in which an analog input signal of a state quantity is received and monitored by a central processing unit in order to control the state quantity to a predetermined target value in accordance with time, the central processing unit The comparison port w1 includes a storage circuit that stores a target value set in a processing device, and a comparison circuit that compares the analog input signal and the target value with each other. An analog input device for a programmable controller, characterized in that it supplies an interrupt request signal to the central processing unit when the central processing unit is activated.