JPS63142912A - Digital signal input device - Google Patents

Abstract

PURPOSE:To prevent an erroneous signal from being inputted to a processing circuit even at an open cord between a switch and the processing circuit by providing delay elements whose time constants differ from each other to input terminals of a RS flip-flop (FF) and constituting the titled device by a power supply giving a signal voltage to the terminals of the FF and a switch selecting the input terminals of the FF. CONSTITUTION:Time constant circuits consisting respectively of a resistor Rs, A capacitor Cs and a resistor Rr, a capacitor Cr are connected respectively to a set and a reset terminal of the RS-FF. In this case, a different time constant is given to the time constant circuits and the input terminal of the RS-FF is selected by the changeover of the switch Sw. Thus, the malfunction taking place at an open cord between the switch SW and the processing circuit A is prevented and the output of the RS-FF is kept to either the set or the reset state according to the difference in the said time constants even at a no signal state due to the open cord by the reapplication of power.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an input device for inputting digital signals to a control circuit.

(Prior art) Digital signal input by a switch is made up of a switch SW and a control circuit X, as shown in FIG. When the input switch SW is turned off, Vcc (H) is input to the processing circuit A, and when the switch SW is turned on, O''7 (L) is input to the processing circuit A.

(Problems to be Solved by the Invention) Usually, the switch SW and the control circuit X are located at separate locations, and they are connected by a cord or a connector. Therefore, the following problems occurred due to cord breakage and poor contact of the connector.

If there is a break in the cord at point P while the switch SW is on, processing circuit A will break even though the switch is on.
The input signal to becomes VCC (H). Since the processing circuit A receives this signal and performs a certain control, there are cases where the intended control result is completely opposite.

The present invention has been made in view of the above-mentioned actual situation, and an object of the present invention is to provide a digital signal input device that does not input an erroneous signal to a processing circuit even when a cord connecting a switch and a processing circuit is disconnected.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides delay elements having different time constants at the input terminals of the RS flip-flop, and supplies signals to the terminals of the RS flip-flop. It is characterized by consisting of a switch that selects the power supply voltage and the input terminal of the RS flip-flop.

(Function) As described above, the present invention prevents malfunctions when the input cord is disconnected by receiving the digital signal through the RSS flip-flop path, and also restarts the power supply even when there is no signal due to the disconnection. By turning on the R terminal S
Due to the difference in time constant of the delay elements connected to the terminals, the output of the RS flip-flop is kept in either a set or reset state.

(*Stream side) An embodiment of the present invention will be described with reference to the drawings.

Set (S) terminal of RS flip-flop, reset (
R) terminals are connected with resistors Rs and Rr, and capacitors Cs and Cr, respectively, and capacitors Qs and Cr are connected.
Ground one end of Qr. The output terminal of the RS flip-flop is connected to a processing circuit A, and the processing circuit A performs control according to the output Q of the RS flip-flop. Resistance Rs,
One end of Rr is connected to a switch SW that selects either the R terminal or the S terminal, and one end of the switch SW is grounded. A power supply voltage Vcc is connected between the switch SW and the resistors Rs and Rr.

Here, resistors R3 and R connected to the RS flip-flop
r, the values of capacitors Cs and Cr, for example Rs, Rr
to 10Ω, and C3 to 0.33μF.

Or is 0.1μF, and the time constants of the resistor and capacitor connected to the S terminal and R@ terminal are Ts -3 and 3, respectively.
m sec and Tr −1 m sec, and increase the time constant on the S terminal side.

With the above configuration, after turning on the power switch (not shown) and switching from switch SW@s to r, (L) is input to the R terminal of the RS flip-flop, and (H> is input to the S terminal of the RS flip-flop. Output Q changes from (H) to (L).At this time, if a disconnection occurs in Pr of the cord connecting switch SW and processing circuit A, (H) will be applied to the R terminal of the RS flip-flop, and (H) will be applied to the S terminal of the RS flip-flop. H) is input, so the output Q of the RS flip-flop maintains its previous state and becomes (
L) maintain the state. That is, the processing circuit A that receives and controls this signal will not malfunction due to a disconnection of the cord.

Also, when the cord is disconnected at pr, switch SW
When switching from r to S, the output Q of the RS flip-flop changes from (L) to (H), and the switch SW changes from S to "
When switching to , the output Q of the RS flip-flop becomes (H)
When the state is maintained and the switch SW is further changed from r to S, the output Q of the RS flip-flop maintains the H state. Therefore, when pr is disconnected, the same signal as when there is no disconnection is output from the RS flip-flop only when the switch SW is switched to the S side.

Also, when the switch SW is changed from r to S after power is turned on, the S terminal of the RS flip-flop O-tub is connected to the S terminal (S), and the R terminal is connected to the R terminal (
H) is input, so the output Q of the RS flip-flop
becomes (L) to (H).

If a disconnection occurs at Ps at this time, (H) is input to the R terminal of the RS flip-flop and (H) is input to the S terminal, so the output Q of the RS flip-flop maintains the previous state and (
H) maintain the state. That is, the processing circuit that receives and controls this signal will not malfunction due to a disconnection of the cord.

Also, when the wire is disconnected at Ps, switch SW is changed from S to r.
When the switch SW is switched from r to S, the output Q of the RS flip-flop changes from (H) to (L).
The output Q of the RS flip-flop maintains the (L) state, and when the switch SW is further switched from S to r, the output of the RS flip-flop maintains the (L) state. Therefore, when there is a disconnection at ps, the same signal as when there is no disconnection is output from the RS flip-flop only when the switch SW is switched to the r side.

When the wire is disconnected at Ps, turn the switch SW to SI! Il
By connecting it to l, turning off the power, and then turning it on again,
The output Q of the S flip-flop can be brought into the (H) state. This is because delay elements with different time constants are connected to the R terminal and S terminal of the RS flip-flop, so the time to reach the (H) state is different.

That is, since the time constant on the S terminal side is set large, it is the same as inputting (H) to the R terminal and (S) to the S terminal after power is turned on. After that, enough time has passed and R@child, S
Even if (H) is input to the terminal, the output Q of the RS flip-flop maintains the previous state, so the output Q becomes (H).

Therefore, by connecting the switch SW to S when pr is disconnected, and by turning the power back on when Ps is disconnected, the output Q of the RS flip-flop is set to the set state (H).
can be kept.

On the Kihiro style side, an element with a large time constant is connected to the S terminal side, but by conversely connecting an element with a large time constant to the R terminal side, the output Q of the RS flip-flop can be reset to the reset state (L ).

The digital input device according to the present invention can be used, for example, as an input section for a lift switch signal of a working machine of an agricultural truck.

As shown in FIG. 2, the agricultural truck 1 is provided with a working machine 3 at the rear thereof which is moved up and down by the lifting and lowering of a lift arm 2, and performs plowing work by pressing this working machine 3 against the ground. work! ! Even if a disconnection occurs between the input part of the lift switch signal and the control circuit for lifting and lowering the lift arm 2 when the lift arm 13 is in the raised position, by using the digital input device of the present invention, the power can be turned on again. The working machine 3 can be positioned on the descending side (work side), and plowing work can be performed even when the wire is broken.

(Effects of the Invention) As described above, the present invention prevents malfunctions due to disconnection of the input cord by receiving digital signals through the RSS flip-flop path, and also prevents malfunctions when the input cord is disconnected. By reinserting the R terminal S
Due to the difference in time constants connected to the terminals, the output of the RS flip-flop can be maintained in either a set or reset state.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a side view of an agricultural tractor using the present invention, and FIG. 3 is a circuit diagram showing a conventional input device. FF・・・・・・・・・・・・RS flip flop O
Tsubu SW・・・・・・・・・・・・Switch VC
C・・・・・・・・・・・・・Power supply voltage △・・・・
...... Processing circuit R3, Rr...
・Resistor C9, Cr... Capacitor Filed on December 5, 1986 Person Kayabae Gyo Co., Ltd. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] The input terminal of the RS flip-flop is provided with delay elements each having a different time constant, and is comprised of a power supply voltage that supplies a signal to the terminal of the RS flip-flop, and a switch that selects the input terminal of the RS flip-flop. Digital signal input device.