JPS6275709A - Programmable controller - Google Patents

Abstract

PURPOSE:To obtain a substantial power saving effect, by supplying electric power to the limit switch input circuit of an input module during a reading time only synchronously to the reading operation of a control unit. CONSTITUTION:A phase detecting signal generating circuit 5 which detects a prescribed phase of the power source 4 of a control unit 3, input controlling signal generating circuit 6 which outputs an input controlling signal in accordance with the phase detecting signal of the circuit 5, and input controlling circuit CF with performs switching control on a limit switch input circuit 2 of input modules so as to drive the circuit 2 during the input reading time of the control unit 3 only irrespectively of the ON/OFF of each limit switch by using the input controlling signal are provided. Therefore, electricity can be supplied to the limit switch input circuit of input modules during the reading time of the control unit only.

Description

[Detailed Description of the Invention] <Industrial Application Field> In the present invention, a program for creating a sequence is set by turning on and off a large number of limit switches, which are external switches, and this on/off state is input to an input module. This invention relates to a programmable controller that operates with the circuit energized or de-energized and reads data at each scan time using a control unit.

<Prior Art> This type of conventional programmable controller has a large number of limit switches Sl, S, as shown in FIG.
2. S3. ..., an operation switch sW, and an AC commercial power source AC are connected in parallel, and the input end of the input module 1 is connected to each limit switch S1, S2, . S3. A limit switch input circuit 2 consisting of a full-wave rectifier and a photocoupler F connected to an AC commercial power supply AC and a limit switch input circuit 2 is connected to each limit switch Sl.

S2. S3. --Provided for each location. Then, a program for creating a sequence is applied to the required limit switches Sl, S2 . S3. -..., and to explain the first limit switch S1 which is now in the on state, the waveform as shown in Fig. 9 (Fig. 81) is The power supply voltage of the commercial power supply AC is supplied to the limit switch input circuit 2 of the input module 1, which is full-wave rectified by a full-wave rectifier into a rectified waveform as shown in FIG. 9('b), and further rectified. , the output waveform of the photocoupler F, which is always on when the limit switch S1 is on, is the same (as shown in Figure 01).Then, the limit switches Sl, S2, S3
The input module 1 operates in the on/off state of ゜- with the limit switch input circuit 2 being energized or de-energized.
The reading operation of the control unit 3 is performed by detecting the vicinity of 0 volts of the commercial alternating current shown in Fig. 10(a) using a zero-cross signal generation circuit (not shown), and at the same time detecting the time period indicated by the downward diagonal line on the left in Fig. 10(a). Input is read and output is written. After that, the same (b1
At time t indicated by the downward diagonal line in the figure, the control unit 3 performs system processing and ladder diagram calculations. This series of processing, including input/output processing, ladder calculations, and system processing, is performed cyclically by zero-cross synchronization triggered by the zero-cross signal (as shown in Figure b1).In other words, in this example, the commercial power supply A series of processes is repeated using a half cycle as a scan cycle.

<Problems to be Solved by the Invention> As is clear from FIG. 9fc1, the limit switches Sl, S2. Current always flows through the input circuit 2 corresponding to S3, but the control unit 3 always reads whether the input circuit 2 is energized or not, as shown in Figure 10(b). The data is read only once every scan time N, and the input/output processing time is usually less than 1/8 of the scan time N, meaning that 7/8 of the time is wasted energy. become. Moreover, this totally wasteful power consumption generates heat, which not only complicates the thermal design of this type of device, but also worsens the environmental conditions of the device.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a programmable controller that can energize the limit switch input circuit of a human power module only during the reading time of the control unit. It is something to do.

Means for Solving the Problems> In order to achieve the above object, the present invention provides a phase detection signal generation circuit that detects a predetermined phase of a power supply of a control unit, and a phase detection signal generation circuit that detects a predetermined phase of a power supply of a control unit, and generates an input control signal based on this phase detection signal. an input control signal generation circuit that outputs an input control signal, and an input that controls switching so that the input control signal drives the limit switch input circuit of the input module only during the input reading time of the control unit, regardless of whether each limit switch is on or off. The gist of the invention is to have a configuration including a control circuit.

<Operation> With the above configuration, the scan cycle of the control unit is synchronized with the AC commercial power supply, so that a phase detection signal is generated at a predetermined phase of the AC commercial power supply corresponding to the input data reading process among the series of processes. An input control signal is generated based on this phase detection signal, and this input control signal operates the input control circuit, and the limit switch input circuit of the input module is energized only during the reading time of the control unit. , and at other times, no current is applied regardless of whether the limit switch is in the on state.

<Example> Examples of the present invention will be described in detail below.

In FIG. 1 showing an embodiment of the present invention, parts that are the same or equivalent to those in FIG. Limit switch input circuit 2 (
1 (only [!iI is shown), an input control circuit CF consisting of a photocoupler is inserted and connected in series, and the input control circuit CF is driven and controlled by an input control signal output from the control unit 3. It is different from the one shown.

Further, as shown in FIG. 2, the power supply circuit 4 of the control unit 3 is provided with a phase detection signal generation circuit 5 that detects a predetermined phase, and the control unit 3 is further provided with a phase detection signal generation circuit 5 that detects a predetermined phase. An input control signal generation circuit 6 consisting of a logic circuit that outputs the above-mentioned input control signal is provided.

With the above configuration, for example, in the control unit 3, input data is input in time period A of the scan time N as shown in FIG. 4(b) in synchronization with the AC power supply voltage shown in FIG. 4(a). If reading processing is performed in time zone B, system processing and ladder diagram arithmetic processing, and output writing is performed in time zone C, the reading process will be performed in synchronization with the human data reading process as shown in Figure (C). An input control signal is output, and each human control circuit CF is turned on by this control signal. Therefore, when an input control signal with a pulse width tl as shown in Fig. 3(b) is output from the control unit 3 with respect to the power supply voltage of the AC power supply AC shown in Fig. 3(a), As shown in the figure, after a short delay time has elapsed, current flows from the full-wave rectifier only for a time corresponding to tl, and is read by the control unit 3. In addition, as an input control signal, as shown in FIG.
A signal having a pulse width obtained by adding a preparatory time signal t until the logic level becomes stable after turning on, that is, a pulse signal having a pulse width as shown in FIG. 8 (8) is output.

Alternatively, a configuration as shown in FIG. 6 or 7 may be used. In each figure, the same or equivalent parts as in Figure 1 are given the same reference numerals.
The input control circuit 7 composed of S and triac TR is connected to each limit switch input circuit 23 of a large module.
.about.2n, and compared to the embodiment shown in FIG. 1 in which input control circuits CF are individually provided for each input circuit 2a to 2n, only one input control circuit 7 is required. The same effect can be obtained with Further, FIG. 7 shows a case where a direct current power supply DC is used, and one input control circuit CF made of a photocoupler is inserted and connected to the common line as in the case of FIG. 6.

It should be noted that the present invention is not limited to the above-mentioned embodiments; for example, the input control signal may be generated by the control unit based on the zero-cross signal.

<Effects of the Invention> As described above, according to the programmable controller of the present invention, power is supplied to the limit switch input circuit of the input module only during the reading time in synchronization with the reading operation of the control unit, so power consumption is reduced compared to the conventional one. In addition to reducing the amount of power to 1/8 or less and achieving a significant power saving effect, the thermal design of the input module becomes easier.
Moreover, there is an advantage that the environmental conditions of the control unit can be improved.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are a wiring diagram and a block configuration diagram of main parts of an embodiment of the programmable controller of the present invention,
Figure 3 is a time chart showing the waveforms of the operating voltages of each part in Figure 1, Figure 4 is a time chart to explain a series of processes of the control unit in Figure 1, and Figure 5 is an explanation of input control signals. 6 and 7 are all connection diagrams of other embodiments of the present invention. Figure 8 is a wiring diagram of a conventional programmable controller, Figure 9 is a time chart showing the operating voltage waveforms of each part in Figure 8),
FIG. 0 is a time chart for explaining a series of processes of the control unit shown in FIG. 89. l...Input module 2.2a-2n...Limit switch input circuit 3...
- Control unit 5... Phase detection signal generation circuit 6... Input control signal generation circuit CF, 7...
Human control circuit patent applicant Sharp Corporation Agent
Patent Attorney Nishi 1) New Figure 1, Figure 3, Figure 4, Figure 5 (Q) - Kuchiichi] - (b) Mother d'n Figure 8

Claims (1)

[Claims] (1) A phase detection signal generation circuit that detects a predetermined phase of the power supply of the control unit, an input control signal generation circuit that outputs an input control signal based on this phase detection signal, and a limit of the input module using this input control signal. 1. A programmable controller comprising: an input control circuit that performs switching control to drive a switch input circuit only during input reading time of the control unit, regardless of whether each limit switch is on or off.