JPH0944281A - Multiplex input device for digital input signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of digital input cards required for inputting signals to a digital device by bisecting the input signal from a signal contact and respectively inputting them to different OR gates so that divided signal paths can not be overlapped. SOLUTION: The signal paths from external signal contacts A-J are bisected and respectively connected to different wired OR gates (a)-(e). The signal paths from the other signal contacts A-J are not connected to the OR gates (a)-(e) of the same combination as the combination of the OR gates (a)-(e) to which the signal paths divided from the respectively signal contacts A-J are connected. The outputs of the OR gates (a)-(e) are respectively connected to digital input cards 1-5. The digital input cards 1-5 respectively convert the signals from the OR gates (a)-(e) to the input signals to the digital device and send them to an arithmetic processing unit (APU) 6. Based on the signals from the digital input cards 1-5, the APU 6 performs decode processing for extracting a certain inputted signal in the range of the signal contacts A to J based on fixed rules.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device having a digital input card.

[0002]

[Prior art]

A digital input card is a device that, when a contact signal from the outside is input to a digital device, converts the signal into a signal level that can be read by the digital device. In such a digital input card, when the input signal is conventionally an important signal, in order to prevent an erroneous signal from being input to the digital device by some action, the same input signal is transmitted to another one. , And only the input signal when the output signals from the two digital input cards match was propagated to the digital device.

[0004]

In the above-mentioned conventional system, the number of digital input cards required is twice as many as the number of input signal points from the signal contacts, and the number of input signal points is increased in a digital device which requires multiple inputs. There was a problem that the more the number, the higher the cost for the digital input card. The present invention aims to solve such problems.

[0005]

In order to solve the above problems, the present invention divides a signal path from a plurality of signal contacts outputting an input signal to a digital device into two, and divides the signal paths into two. A plurality of OR gates provided so that signal paths do not overlap and are not input to the same OR gate, a digital input card which receives the output of the OR gate in a one-to-one correspondence with the OR gate, and an output from the digital input card Based on the above, it is composed of an arithmetic processing unit that extracts the signal contacts input “on” or “off”, and the number of signal contacts is p
When the number of digital input cards is n, the following relationships (a) and (b) are satisfied.
(B) The following relational expression holds between n and p. (B) The number of input pins of the OR gate is (n-1), and the number of output pins is one.

The operation of the present invention is as follows. That is, the input signal from the signal contact is divided into two and input to different OR gates. A signal path from another signal contact is not connected to an OR gate having the same combination of OR gates to which a signal path divided from each signal contact is connected. To do. Each OR gate calculates the logical sum of the input signals and outputs it as a 1-bit signal. The signal from each OR gate is input to the digital input card that corresponds to each OR gate in a one-to-one correspondence, and is converted into a signal to a digital device. The arithmetic processing unit extracts which input signal the input signal is input from based on the combination of the signals from each digital input card, and also confirms whether there is any abnormality in the transmission state.

A combination in which the output of two OR gates out of n OR gates becomes "1" is If there are p signal contacts, The number of OR gates satisfying the above condition, that is, the number n of digital input cards is obtained. The number of digital inputs with respect to the number of signal contacts is as shown in FIG.

Further, since the number of signal paths is twice as many as the number of signal contacts p by n OR gates, the number of pins for input to the OR gate is (n-1).

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an example of a multiplex input device for digital input signals according to the present invention. In the figure, there are 10 external signal contacts A to J. The signal paths from the same signal contacts A to J are divided into two parts, which are respectively connected to different wired OR gates a to e.
The wired OR gates a to e use 4-input 1-output gates.

The paths from the signal contacts A to J are divided into two, and then connected to different wired OR gates. The signal path from another signal contact shall not be connected to the same combination of OR gates to which the signal path divided from each signal contact is connected. That is, for example, when the signal path obtained by dividing the signal contact A into two is connected to the OR gates a and b, the signal paths from the other signal contacts B to J are not connected to the combination of the OR gates a and b. To do. When each signal contact and OR gate are connected as described above, only the output of the two OR gates connected to the signal contact outputting "1" becomes "1", and the other signal contact outputs "1". When outputting, the output of the OR gate cannot be "1" in the same combination as this. Therefore, the state of the signal contact can be detected from the result of the output of the OR gate, and it can be confirmed whether the signal transmission state is normal or abnormal.

In the case of this embodiment, the path from the signal contact A is divided into two and then connected to the wired OR gates a and b. Similarly, the path from the signal contact B to the wired OR gates a and c, the path from the signal contact C to the wired OR gates a and d, the path from the signal contact D to the wired OR gates a and e, and the signal contact The path from E to wired OR gates b and c, the path from signal contact F to wired OR gates b and d, and signal contact G
To the wired OR gates b and e, the path from the signal contact H to the wired OR gates c and d, and the path from the signal contact I to the wired OR gates c and e.
, And the path from signal contact I is connected to wired OR gates d and e, respectively.

The outputs of the wired OR gates a to e are connected to the digital input cards 1 to 5, respectively. The digital input cards 1 to 5 respectively convert the signals from the wired OR gates a to e into input signals to the digital device and send them to the arithmetic processing device 6. The arithmetic processing unit 6 performs a decoding process for extracting which signal from the signal contacts A to J is input according to the rule of FIG. 2 based on the signal from the digital input card. That is, for example, when the signal outputs from the wired OR gates a and b are “1” and the signal outputs from the wired OR gates c, d and e are “0”, the input signal “1” from the signal contact A is “1”. A process for extracting that "" has been input is performed. Wired or gate a to e
2 does not satisfy the relationship shown in FIG. 2, the arithmetic processing unit 6 determines that there is an abnormality in the signal transmission state, and informs an alarm device or a display device (not shown) of that fact.

[0013]

According to the present invention, even if the number of input signal points from the signal contacts increases, the number of digital input cards can be reduced, and the cost of the cards can be saved. The number of digital input cards required for the same number of signal contacts in the present invention and the conventional method is as shown in FIG.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a digital input signal multiplex input device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a decoding processing rule in an arithmetic processing unit according to an embodiment of the present invention.

FIG. 3 is a correspondence table showing the number of digital input cards required for the number of signal contacts according to the present invention.

FIG. 4 is a table showing the required number of digital input cards in the present invention and the conventional system.

[Explanation of symbols]

 1, 2, 3, 4, 5 Digital input card 6 Processor A, B, C, D, E, F, G, H, I, J Signal contact a, b, c, d, e Wired OR gate

Claims (1)

[Claims] 1. A signal path from a plurality of signal contacts for outputting an input signal to a digital device is divided into two, and the divided signal paths are provided so as not to be overlapped and inputted to the same OR gate. A plurality of OR gates, a digital input card that corresponds to the OR gate in a one-to-one manner and receives the output of the OR gate, and a signal contact input “ON” or “OFF” based on the output from the digital input card. The number of signal contacts is p,
A multiple input device for digital input signals, wherein the following relationships (a) and (b) are satisfied when the number of digital input cards is n. (B) The following relational expression holds between n and p. (B) The number of input pins of the OR gate is (n-1), and the number of output pins is one.