JP2011191875A - Signal transmission control method in plc system and the plc system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a PLC system including a body unit and an expansion unit to accurately control a control object without causing malfunction by issuing a sleep command from the body unit to the expansion unit since a power source is applied in the body unit until the reset period of a CPU part passes, and transmitting a signal from the expansion unit to the body unit by releasing the sleep command when the CPU part normally functions. <P>SOLUTION: The PLC system has a means 23a for, since the reset period of a CPU part 13 in a body unit 1 passes until a DC voltage to be supplied to the CPU part 13 reaches its operating voltage, outputting a sleep signal to put the signal transmitting operation of an expansion unit 2 into a sleep state from the CPU part 13 to the expansion unit 2, and for, when the DV voltage reaches the operating voltage of the CPU part 13 after the lapse of the reset period, outputting a sleep release signal to release the sleep state. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a signal transmission control method between two units in a PLC (programmable controller) system including a main unit and one or more extension units.

  The PLC system includes a main unit (also referred to as a CPU unit) and includes one or a plurality of expansion units as functions are increased. The PLC incorporates a CPU (Central Processing Unit) in the main unit, and the CPU in the main unit executes a user-created program such as a ladder program stored in a program memory in the main unit. It can control a controlled object such as an apparatus and is widely used.

  In the PLC system, the function can be expanded and expanded by providing an expansion unit for the main unit. And in such a main body unit, the power supply part which supplies a DC voltage to these as an operating voltage with a circuit part containing CPU part inside is provided. Many of these power supply sections operate these circuits by supplying, for example, DC 5V, 12V, 3.3V, etc. to the circuit section. Therefore, the power supply section uses a commercial power supply as an external power supply and uses the commercial power supply. Is subjected to AC / DC conversion, and further DC / DC conversion corresponding to the type of DC voltage is performed to obtain a required direct current and supply it to each part in the PLC. Further, for example, 24V DC is supplied from the main unit to the expansion unit, and the DC 24V is converted into 3.3V DC inside the expansion unit and supplied to the internal circuit.

  A conventional PLC system will be described with reference to FIGS. In FIG. 3, 1 is a main unit, and 2 is an expansion unit. A plurality of expansion units 2 may be provided, but one unit is shown for convenience of illustration. The main unit 1 includes a power supply unit 11, a main body circuit unit 12, and a CPU unit 13. The power supply unit 11 converts an AC voltage input from the power plug 3 through the power switch 4 into a DC voltage, and a DC voltage output from the AC / DC conversion unit 11a. And a DC / DC converter 11b for converting and outputting the direct current voltage. The main body circuit unit 12 includes a program memory, a data memory, an input / output interface, a communication interface, and the like, and is shown in one block configuration for convenience of illustration. The DC / DC conversion unit 11b of the power supply unit 11 supplies, for example, 5V, 12V, etc. to the main body circuit unit 12, while supplying 3.3V, for example, to the CPU unit 13.

  The expansion unit 2 includes a power supply unit 21 and an expansion circuit unit 22. The power supply unit 21 is supplied with 24 V DC from the power supply unit 11 of the main unit 1, and can convert the supplied 24 V DC to 3.3 V DC and supply it to the expansion circuit unit 22.

  The main circuit unit 12 of the main unit 1 and the expansion circuit unit 22 of the expansion unit 2 are connected by a signal line (bus) 5, and the main unit 1, the power unit 11 of the main unit 1, and the power unit 21 of the expansion unit 2 are powered. Connected by line 6.

  The operation of the PLC system configured as described above will be described with reference to FIG.

  First, at time t0, the power plug 3 is inserted into a commercial AC power supply (not shown) and the power switch 4 is turned on. When the time from when the power switch 4 is turned on until the AC voltage is stabilized is T0, the AC voltage is stabilized at time t1.

The AC voltage is converted into a DC voltage by the AC / DC conversion unit 11a of the power supply unit 11 of the main unit 1, and the converted DC voltage is converted into another DC voltage by the DC / DC conversion unit 11b. In this case, since the conversion requires time T1, the conversion time is time t2.
The converted voltage is, for example, DC 5V, 3.3V, 12V, 24V. Among them, DC 5V and 12V are applied to the body circuit unit 12 at time t2, 3.3V DC is applied to the CPU unit 13, and 24V DC is applied to the power supply unit 21 of the expansion unit 2 at the same time t2. Supplied. The direct current 24V applied to the power supply unit 21 of the expansion unit 2 is converted into direct current 3.3V here. The time required for this conversion is T2, and the conversion time is time t3.

  On the other hand, the main circuit unit 12 of the main unit 1 is in an operable state by the application of the direct current 5V, 12V, etc., but the CPU 13 is initialized even if the direct current 3.3V is applied. A reset period T3 is necessary, and the time when the CPU 13 becomes operable is time t4.

  That is, in the extension circuit section 22 of the extension unit 2, 3.3V DC is applied from the power supply section 21 and is already operable after time t3, but the CPU section 13 of the main unit 1 It is not in an operable state between t2 and t4.

JP 2007-323103 A JP 2000-181511 A

  In the PLC system shown in FIG. 3, a signal is transmitted to the main body circuit portion 12 of the main body unit 1 from the expansion circuit portion 22 of the expansion unit 2 that is already operable after the time t3. On the other hand, in the main unit 1, during the period from the time t2 to the time t4, the CPU unit 13 is in the reset period and is not in the operating state, so the signal transmitted from the expansion unit 2 is received from the time t3 to the time t4. Cannot be performed, and there is a possibility that the control of the PLC system may be hindered.

  Therefore, the main unit 1 side is controlled so that no signal is transmitted from the expansion unit 2 until the reset period of the CPU unit 13 elapses, and the signal is transmitted to and from the expansion unit 2 after the reset period elapses. It needs to be controlled so that it can be done.

  However, the main body unit 1 has a problem that the CPU unit 13 does not stand up during the reset period, and thus cannot perform such control on the expansion unit 2.

  Therefore, in the present invention, a command is issued so that the main unit 1 does not transmit the signal to the expansion unit 2 even during a period in which the main unit 1 is not started up after the power supply is applied and until the reset period elapses. It is possible to solve the above-mentioned problems.

The signal transmission control method in the PLC system according to the present invention includes a main unit and an extension unit that is supplied with power from the main unit and transmits signals to and from the main unit.
The main unit converts an AC voltage into a DC voltage, converts the DC voltage into one or more other DC voltages, and delays the DC voltage from the power supply unit by a CPU reset period as an operating voltage. A CPU unit that is supplied and operates,
The extension unit is supplied with a DC voltage from the main unit power source, and converts the supplied DC voltage into an operating voltage at a timing earlier than a reset period of the CPU of the main unit, and the power unit An expansion circuit unit that is supplied with an operating voltage and transmits signals to and from the CPU unit of the main unit.
In the PLC system,
A signal transmission control method between the two units,
A first step of detecting a ground potential during the reset period and after the reset period has elapsed in the CPU unit of the main unit;
A ground potential during the reset period is set as a sleep command logic signal, and a ground potential after the reset period has elapsed is set as a sleep cancel logic signal. Based on these both logic signals, a second signal for controlling signal transmission from the expansion unit to the main unit is controlled. Steps,
It is characterized by including.

  In the present invention, since the power supply to the CPU unit does not rise until the reset period of the CPU unit elapses after the power supply is applied, the ground potential of the CPU unit detected in the first step is the sleep command logic signal. Also, after the reset period of the CPU unit has elapsed since the application of power, the power to the CPU unit rises, and the ground potential of the CPU unit detected in the first step is set as a sleep release logic signal, and this set logic signal Since the transmission of the signal from the extension unit to the main unit is controlled, the signal transmission between the two units will be performed after the CPU unit of the main unit has been started up to ensure system control. As a PLC system, it becomes possible to reliably control an object to be controlled without malfunction.

  Preferably, in the first step, a resistor is connected between the grounding terminal of the CPU unit of the main unit and the grounding unit, and the ground potential during the reset period and after the lapse of the reset period is determined from the voltage across the resistor. This is a detecting step.

  Preferably, the second step inputs a signal from the expansion circuit unit of the expansion unit to one of at least two input units of the AND gate, inputs the logic signal to the other, and outputs the AND gate. This is a step of transmitting the signal from the unit.

The PLC system according to the present invention comprises:
Including a main unit and an expansion unit that is supplied with power from the main unit and transmits signals to and from the main unit.
The main unit converts an AC voltage into a DC voltage, converts the DC voltage into one or more other DC voltages, and operates the DC voltage delayed from the main unit by a CPU reset period. A CPU unit that operates by being supplied as a voltage,
The extension unit is supplied with a DC voltage from the main body power supply unit and converts the supplied DC voltage into an operating voltage at a timing earlier than a reset period of the CPU unit of the main unit, and the extension power source An expansion circuit unit that is supplied with an operating voltage from the unit and transmits signals to and from the CPU unit of the main unit.
A PLC system,
A ground potential detecting means that is connected to the ground terminal of the CPU unit of the main unit and detects the potential of the ground terminal during the reset period and after the reset period of the CPU unit;
The ground potentials corresponding to the reset period and after the reset period have elapsed are set as sleep command logic and sleep cancel logic, respectively, and when this setting logic is the sleep command logic, signal output from the expansion unit is prohibited and the sleep cancel logic Signal transmission permission / prohibition means to cancel the prohibition of signal output,
Is provided.

  According to the present invention, in the main unit, the signal is not transmitted from the main unit to the expansion unit even during the period when the CPU unit is not started up after the power supply is applied and until the reset period of the CPU unit elapses. Therefore, the control target can be reliably controlled without malfunction as a PLC system.

FIG. 1 is a diagram showing a configuration of a PLC system according to an embodiment of the present invention. FIG. 2 is a time chart for explaining the operation of the PLC system of FIG. FIG. 3 is a diagram showing a configuration of a conventional PLC system. FIG. 4 is a time chart for explaining the operation of the PLC system of FIG.

  Hereinafter, a PLC system according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  The PLC system will be described with reference to FIG. FIG. 1 is a diagram showing a configuration of a PLC system according to an embodiment of the present invention, and parts corresponding to those in FIG. Although there is an overlap with the description in FIG. 3, it will be described below.

  In FIG. 1, 1 is a main unit, and 2 is an expansion unit.

  The main unit 1 includes a power supply unit 11, a main body circuit unit 12, and a CPU unit 13.

  The power supply unit 11 converts an alternating voltage input from the power plug 3 via the power switch 4 into a direct current voltage, and converts the converted direct current voltage into a plurality of different direct current voltages so as to be output. It has become. The power supply unit 11 also supplies 5V, 12V, etc. to the main body circuit unit 12 while supplying 3.3V to the CPU unit 13.

  The main body circuit unit 12 includes a program memory, a data memory, an input / output interface, a communication interface, and the like.

  The CPU unit 13 can control a control target (not shown) via the main body circuit unit 12 by executing a ladder program or the like that is a user-created program stored in a memory built in the main body circuit unit 12. Yes.

  The expansion unit 2 includes a power supply unit 21, an expansion circuit unit 22, and a signal transmission permission / inhibition unit 23 described later.

  The power supply unit 21 is supplied with 24V DC from the power supply unit 11 of the main unit 1 through the power supply line 6, and can convert the supplied 24V DC to 3.3V DC and supply it to the extension circuit unit 22. It is like that.

  The extension circuit unit 22 inputs / outputs a signal from an input / output device (not shown) attached to the extension circuit, and transmits a signal corresponding to the extension circuit unit 22 to the main unit 1 via the signal line 5. Be able to.

  With the above configuration, the characteristics of the PLC system of the embodiment will be described. The CPU unit 13 of the main unit 1 includes a power supply terminal 13a to which 3.3V DC is supplied from the power supply unit 11, and a ground terminal 13b through which a ground current flows. A resistor 8 is provided between the ground terminal 13 b and the ground portion 7. This resistor 8 constitutes a ground potential detecting means 9 for detecting the potential of the ground terminal 13b during the reset period T3 of the CPU unit 13 of the main unit 1 and after the reset period T3.

  In addition, the PLC system of the embodiment includes the signal transmission permission / inhibition means 23 that is a logic block for inputting logic “0” and “1” in the expansion unit 2. The means 23 includes an AND gate 23a and a buffer gate 23b. The AND gate 23a receives the transmission signal from the extension circuit unit 22 and the logic signal from the ground potential detecting means 9, and when the logic signal is “0”, the transmission of the transmission signal is prohibited. When “1” is “1”, output of the transmission signal is permitted. A signal from the main unit 1 side can be transmitted to the expansion unit 2 via the buffer gate 23b.

  Hereinafter, the operation of the PLC system of the embodiment shown in the above configuration will be described with reference to FIG.

  First, at time t0, the power plug 3 is inserted into an AC power supply (not shown) and the power switch 4 is turned on. The time from when the power switch 4 is turned on until the AC voltage is stabilized is T0, and the AC voltage is stabilized from time t0 to time t1 after elapse of time T0.

  Next, the AC voltage is converted into a DC voltage by the power supply unit 11 of the main unit 1, and the converted DC voltage is converted into a plurality of other DC voltages, for example, 3.3V, 5V, 12V, 24V, and the like. Is done. In this case, since time T1 is required for the conversion, the time at which the conversion voltage stabilizes is time t2 after time T1 has elapsed from time 1.

  In the converted voltage, DC 5V and 12V are applied to the main body circuit unit 12 at time t2, 3.3V DC is applied to the CPU unit 13, and the power source unit 21 of the expansion unit 2 is applied to the power source unit 21 at the same time. 24 VDC is supplied to t2.

  On the other hand, the direct current 24V applied to the power supply unit 21 of the expansion unit 2 is converted into direct current 3.3V here. The time required for this conversion is T2, and the conversion time is time t3.

  The main circuit unit 12 of the main unit 1 is already in an operable state at the time t2 when the direct current 5V, 12V, etc. is applied, but the CPU 13 is in an initial state even if the direct current 3.3V is applied. The reset period T3 is necessary for the conversion to the time and the like, and the time when the CPU 13 becomes operable is the time t4. This is a time later than the time t3.

  Next, in the embodiment, even if the direct current 3.3V is applied from the power source unit 21 to the expansion circuit unit 22 of the expansion unit 2 and is already operable after time t3, the expansion unit The sleep control can be performed so that no signal is transmitted from 2 to the main unit 1.

  That is, the CPU unit 13 of the main unit 1 does not operate immediately even when DC 3.3V is supplied from the power supply unit 11 to the power supply terminal 13a, but gradually increases over the reset period T3. Is raised and applied. Therefore, the CPU unit 13 can operate after the reset period T3 has elapsed since the direct current of 3.3 V is supplied from the power supply unit 11. FIG. 2 shows the waveform of the voltage supplied to the CPU unit 13 and the waveform of the voltage supplied to the expansion circuit unit 22 of the expansion unit 2. The voltage supplied to the CPU unit 13 gradually increases during the reset period T3 from time t3 and becomes 3.3V at time t4. On the other hand, the voltage supplied to the expansion unit 2 is already 3.3 V at time t3, and the expansion unit 2 is in a state where signals can be transmitted.

  In the ground potential detecting means 9 constituted by the resistor 8, the ground current i gradually flows as the voltage to the CPU unit 13 gradually increases during the reset period T3 starting from the time t2, and the resistor 8 The voltage between both ends gradually increases. In the ground potential detecting means 9, the voltage (ground voltage) when the voltage between both ends is equal to or lower than a certain voltage is set as a logic signal “0” of the sleep command, and the ground voltage when exceeding the certain voltage is the logic for canceling the sleep. The signal “1” can be output to the signal transmission permission / inhibition means 23 of the extension unit 2. This constant voltage is a voltage when the reset period T3 of the CPU unit 13 has passed and a voltage that allows the CPU unit 13 to operate normally is supplied.

  The AND gate 23a in the signal transmission permission / inhibition means 23 inputs the transmission signal from the extension circuit unit 22 and the logic signal from the ground potential detection means 9, and when the logic signal is “0”, the transmission signal When the logic signal is “1”, the output of the transmission signal is permitted.

  In summary, the CPU unit 13 cannot operate as the reset period T3 from time t2 to t4, and the expansion unit 2 can transmit a signal after time t3, but sleeps from time t3 to time t4. Transmission of signals from the expansion unit 2 to the main unit 1 is prohibited during the period T4, and transmission of signals from the expansion unit 2 to the main unit 1 is permitted as the sleep release period T5 after the time t4.

  As described above, in this embodiment, after the power switch 4 is turned on and an AC voltage is applied from the power plug 3 to the main unit 1, the reset period T3 of the CPU unit 13 in the main unit 1 has elapsed. In the meantime, even if the power of the CPU unit 13 is not turned on, a sleep command logic signal can be output from the main unit 1 to the expansion unit 2 to make the expansion unit 2 sleep. When the reset period T3 elapses, the main unit 1 can output a sleep cancel command logic signal to the expansion unit 2 to release the expansion unit 2 from the sleep state. As a result, the signal from the expansion unit 2 is transmitted only when the CPU unit 13 can reliably control the entire PLC system, and the PLC system ensures that the control target is not malfunctioned after power is applied. Will be able to control.

DESCRIPTION OF SYMBOLS 1 Main body unit 11 Power supply part 12 Main body circuit part 13 CPU part 2 Expansion unit 21 Power supply part 22 Expansion circuit part 23 Signal transmission permission / prohibition means 3 Power plug 4 Power switch 5 Signal line 6 Power line 9 Ground potential detection means

Claims (4)

A main unit, and an expansion unit that is supplied with power from the main unit and transmits signals to and from the main unit,
The main unit converts an AC voltage into a DC voltage, converts the DC voltage into one or more other DC voltages, and operates the DC voltage delayed from the main unit by a CPU reset period. A CPU unit that operates by being supplied as a voltage,
The extension unit is supplied with a DC voltage from the main body power supply unit and converts the supplied DC voltage into an operating voltage at a timing earlier than a reset period of the CPU unit of the main unit, and the extension power source An expansion circuit unit that is supplied with an operating voltage from the unit and transmits signals to and from the CPU unit of the main unit.
In the PLC system,
A signal transmission control method between the two units,
A first step of detecting a ground potential during the reset period and after the reset period has elapsed in the CPU unit of the main unit;
A ground potential during the reset period is set as a sleep command logic signal, and a ground potential after the reset period has elapsed is set as a sleep cancel logic signal. Based on these both logic signals, a second signal for controlling signal transmission from the expansion unit to the main unit is controlled. Steps,
A signal transmission control method comprising:   The first step is a step of connecting a resistor between the ground terminal of the CPU unit of the main unit and the ground unit, and detecting a ground potential during the reset period and after the reset period from the voltage across the resistor. The method of claim 1, wherein   The second step inputs a signal from the expansion circuit unit of the expansion unit to one of at least two input units of the AND gate, inputs the logic signal to the other, and outputs the logic signal from the output unit of the AND gate. The method according to claim 1, wherein the method is a step of transmitting a signal. Including a main unit and an expansion unit that is supplied with power from the main unit and transmits signals to and from the main unit.
The main unit converts an AC voltage into a DC voltage, converts the DC voltage into one or more other DC voltages, and operates the DC voltage delayed from the main unit by a CPU reset period. A CPU unit that operates by being supplied as a voltage,
The extension unit is supplied with a DC voltage from the main body power supply unit and converts the supplied DC voltage into an operating voltage at a timing earlier than a reset period of the CPU unit of the main unit, and the extension power source An expansion circuit unit that is supplied with an operating voltage from the unit and transmits signals to and from the CPU unit of the main unit.
A PLC system,
A ground potential detecting means that is connected to the ground terminal of the CPU unit of the main unit and detects the potential of the ground terminal during the reset period and after the reset period of the CPU unit;
The ground potentials corresponding to the reset period and after the reset period have elapsed are set as sleep command logic and sleep cancel logic, respectively, and when this setting logic is the sleep command logic, signal output from the expansion unit is prohibited and the sleep cancel logic Signal transmission permission / prohibition means to cancel the prohibition of signal output,
A PLC system characterized by comprising:

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