JPH0737183Y2 - Data display circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a data display circuit provided in a system device such as a programmable controller or an NC device.

(Prior Art) The input / output unit of such a system device is usually provided with a display circuit for displaying the state of data to be handled. This type of data display circuit is conventionally constructed by inserting display means, for example, a light emitting element such as an LED, in series or in parallel to the data line of the input / output unit. FIG. 3 shows an example of a conventional data display circuit provided on the output unit side.

In the display circuit of FIG. 3, the LED 6 is inserted in series in the output data line 1, and the data sent from the microprocessor (not shown) through the output data line 1 is LE.
D6 is turned on and data is displayed. Further, the photocoupler 5 operates with this data, and outputs the output corresponding to the data to the outside. Reference numeral 2 is the output data line 1
Shows the buffer inserted in.

(Problems to be solved by the invention) In such a conventional data display circuit, since the LED is inserted in the data line, it is not possible to turn on the LED regardless of the input / output data during operation of the device. Can not. This means that the LED cannot be checked while the equipment is in operation. When the LED does not light up normally during operation of the device, it is extremely important for the device user to judge whether the LED is simple or the data transmission system is defective. As described above, the conventional data display circuit in which it is not possible to check whether or not the display means is normal while the device is in operation must be said to have a serious problem.

The present invention has been made in view of the above circumstances, and provides a data display circuit in which the display means can be easily checked even while the equipment is in operation and the original data display function is not hindered. With the goal.

(Means for Solving the Problems) Branch line branched from data line, transmitting means for issuing inspection signal, timed circuit for outputting signal when the inspection signal is input, and for clearing output signal after elapse of a predetermined time ，
The data sent through the branch line and the output signal of the time limit circuit are input, and one of a display signal and a non-display signal corresponding to the data is output according to the data, and the output signal is output. A gate circuit that outputs a display signal based on the display circuit and a display unit that changes its state based on the output of the gate circuit are provided, thereby achieving the above object.

(Operation) According to the data display circuit of the present invention, the data transmitted through the data line is given to the gate circuit through the branch line during the operation of the device, and the gate circuit divides the display signal and the non-display signal corresponding to the data. One of them is output according to the data, and the state of the display means is changed based on the output to display the data. When the inspection command is transmitted from the transmission means, this is given to the gate circuit, and the display signal output from the gate circuit is sent to the display means to change the state of the display means. It is checked whether the display means is normal by checking whether the state of the display means changes. In this way, the operation of the display means is checked even while the equipment is operating. Since the data display circuit is branched from the data line, it is not necessary to intervene the inspection command in the data line and the data transmission by the data line is not disturbed. Further, since the inspection command is automatically cleared by the timed circuit after the lapse of a predetermined time, the display means automatically returns to the original state even if the inspection command is continuously transmitted.

(Embodiment) An embodiment of the present invention will be described below.

FIG. 1 shows a circuit diagram of an embodiment of the present invention. In this embodiment, the branch line 10 is drawn out from the output side of the buffer 2 inserted in the output data line 1, and the branch line 10 and the output line 30 of the time limit circuit 3 are the input terminals of the gate circuit 4 which is an OR circuit. It is connected to the.

The time limit circuit 3 includes a NOT circuit 31, an OR circuit 32, a multistage counter 33 and a NOR circuit 34. The output from the transmitting means 7 having the push button switch 7a and the like is input to the NOT circuit 31 and the NOR circuit 34, and the clock signal is input to the OR circuit 32. NOT circuit 3
The output of 1 is input to the reset terminal R of the multi-stage counter 33,
The output of the OR circuit 32 is input to the input terminal C of the multistage counter 33. The output from the MSB terminal (maximum digit terminal) of the output terminals of the multi-stage counter 33 is input to the OR circuit 32 and the NOR circuit 34, and the output of the NOR circuit 34 is input to the gate circuit 4 through the output line 30. . The output of the gate circuit 4 is input to the display means 8 including an LED.

In the data display circuit shown in FIG. 1, when the device to which the output data line 1 is connected is operating, data is transmitted through the output data line 1. This data is sent to the display means 8 through the branch line 10 and the gate circuit 4,
Turn on the LED. The data transmitted through the output data line 1 operates a photo coupler or the like (not shown) inserted in the output data line 1 to send a necessary output to the outside.

When the push button switch 7a is operated during such an operation of the device and the inspection command is output from the transmitting means 7 as the L signal, the signal is input to the NOT circuit 31 and the NOR circuit 34 of the time limit circuit 3. The L signal input to the NOT circuit 31 becomes an H signal and is input to the reset terminal R of the multistage counter 33, whereby the multistage counter 33 starts counting the clock signal. NO
Since the L signal is input from the multi-stage counter 33 to the R circuit 34, the L signal is input from the transmitting means 7 at the same time as the H signal is input.
The signal is output to the gate circuit 4. Thus, the display means 8
In, if the LED is normal, it lights up and the LED can be checked.

If the transmission of the inspection command, that is, the L signal from the transmitting means 7 is stopped, the H signal is input to the NOR circuit 34 and its output returns to the L signal. As a result, the lighting of the LED of the display means 8 based on the inspection command is stopped.

When the push button switch 7a is continuously pressed and the inspection command is continuously transmitted from the transmitting means 7, the multistage counter 33 continues to operate. Therefore, when the H signal is output from the MSB terminal of the NOR circuit 34. Output changes to L signal,
The lighting of the LED of the display means 8 is stopped as when the inspection command is stopped. In the multi-stage counter 33, the H signal from the MSB terminal is continuously input to the input terminal C through the OR circuit 32, so that the counting operation is stopped. As a result, even if the transmitting means 7 continues to operate the switch 7a, the lighting state of the LED on the display means 8 side automatically returns to the original state.

The data display circuit shown in FIG. 1 requires as many gate circuits 4 as the number of data bits, so that the circuit configuration becomes complicated when the number of bits is large. In such a case, it is preferable to use an LED display module driven by serial data as shown in FIG.

In the data display circuit shown in FIG. 2, a large number of data transmitted through the data bus 100, which is a data line, is stored in the data latch 101, and the stored large number of data is a plurality of 1
The multiplexor 102 of the second stage combines them into a plurality of serial data. The serial data collected in multiple,
Each is input to the gate circuit (AND circuit) 104. The output from the time limit circuit 103 is input to each gate circuit 104 together with the serial data. The output of each gate circuit 104 is combined into one serial data by the second-stage multiplexer 105, and the level is converted to drive the serial data.
It is sent to the LED display module 108. The time circuit 103 is the first
A circuit substantially similar to the time limit circuit 3 shown in the figure is adopted. However, at the time of checking, the L signal is output to the gate circuit 104. The controller 9 controls the operations of the multiplexers 102 and 105 based on the clock signal. The multiplexer 105 of the second stage is provided in the subsequent stage of the gate circuit 104 because it has a synchronization deviation self-recovery system called a clear bit.

In the data display circuit shown in FIG. 2, when the check is not performed, the H signal is input from the time limit circuit 103 to the gate circuit 104. Since an AND circuit is used as the gate circuit 104, when data is input from the first stage multiplexer 102, the input signal is output to the second stage multiplexer 105. The signal input to the second-stage multiplexer 105 is level-converted and converted into serial data.
It is transmitted to the LED display module 108. As a result, when the H signal is input from the time limit circuit 103 to the gate circuit 104, the LED display module 108 is turned on corresponding to the data transmitted on the data bus 100, and normal data display is performed. When the L signal is input from the time limit circuit 103 to the gate circuit 104, the L signal is output from the gate circuit 104.
On the ED display module 108, all the LEDs are turned on, and the LED lighting check is performed. The L signal input from the time limit circuit 103 to the gate circuit 104 automatically returns to the H signal after a lapse of a predetermined time even if the transmitter 7 forgets to return the lighting check operation, and the lighting state of the LED display module. Returns to its original state. According to the present embodiment, even if the data is 64 bits, the number of gate circuits 104 can be 8 if the 8-bit multiplexers 102 and 105 are used.

Although the above embodiment is an example of the output unit, the present invention can be applied to the input unit, and the gate circuit and the time circuit are not limited to the above embodiment.

(Effect of the Invention) The data display circuit of the present invention can check the display means such as LEDs even while the equipment is in operation, and this check can be performed regardless of data transmission. Further, even if the check operation is continued, it has a function of returning the data display to the original state, so that the original data display is not adversely affected at all. Furthermore, since the state of the display means can be changed irrespective of the data transmission, it is also possible to search for the target input / output unit or perform a display not directly related to the input / output data. .

[Brief description of drawings]

1 and 2 are circuit diagrams of an embodiment of the present invention, and FIG. 3 is a circuit diagram of a conventional example. 1,100 ... Data line, 3,103 ... Time circuit, 4,104 ... Gate circuit, 7 ... Transmission means, 8 ... Display means (LED), 10 ... Branching line, 108 ... LED display module.

Claims (1)

[Scope of utility model registration request] 1. A branch line branched from a data line, a transmitting means for issuing an inspection signal, a time circuit for outputting a signal when the inspection signal is input, and clearing the output signal after a lapse of a predetermined time, the branch. The data sent through the line and the output signal of the timing circuit are input, and one of a display signal and a non-display signal corresponding to the data is output according to the data, and based on the output signal. A data display circuit including a gate circuit for outputting a display signal and a display unit whose state changes based on the output of the gate circuit.