JPH0625082Y2 - Multiplexer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a multiplex transmission device for transmitting a plurality of signals through a pair of signal lines, and is used in the field of remote control, remote monitoring, etc. Is.

[Prior Art] Conventionally, a time division multiplex transmission device or a frequency division multiplex transmission device has been proposed as a multiplex transmission device capable of transmitting a plurality of control states and a plurality of monitoring states to a remote place via a pair of signal lines. There is. In the time division multiplex transmission device, a pair of signal lines is divided into a plurality of time zones on the time axis, and a plurality of control states and monitoring states can be transmitted depending on the presence or absence of a signal in each time zone. Further, in the frequency division multiplexing transmission device, a pair of signal lines is divided into a plurality of frequency bands on the frequency axis, and a plurality of control states and monitoring states can be transmitted depending on the presence or absence of a signal in each frequency band.

[Problems to be Solved by the Invention] However, in the time division multiplex transmission apparatus, there is a problem that the configuration becomes complicated because it is necessary to synchronize the time axes of the transmission apparatus and the reception apparatus. Further, the frequency division multiplex transmission apparatus has a problem that a large number of filter circuits are required to divide the frequency axis in the reception apparatus, resulting in a complicated structure and high cost.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a relatively small scale by using a relatively inexpensive and highly reliable push button signal transmitter and decoder. It is to provide a multiplex transmission device suitable for the purpose.

[Means for Solving the Problems] In the multiplex transmission apparatus according to the present invention, in order to solve the above problems, as shown in FIG. 1, first to fourth high frequency selection terminals H are provided. _{1 to} H ₄ and first to fourth low band frequency selection terminals L _{1 to} L _4, and a DTMF for transmitting a push button signal composed of a combination of any one high band frequency and any one low band frequency. Transmitter 11, 16 or less binary inputs 12, 4-bit digital counter 13 that counts up in a predetermined cycle, and binary input 1 specified by the count value of digital counter 13
When the scanner 14 that scans the state of 2 and the binary input 12 that is scanned by the scanner 14 have the logical value of either "1" or "0", the DTMF oscillator 11 outputs 1
Transmitter 1 including one high frequency selection terminal and one decoder 15 that decodes the count value of the digital counter 13 so that one low frequency selection terminal becomes active.
And a DTMF decoder 21 which decodes the push button signal to output 4-bit digital data and outputs a push button signal detection signal, and a push button signal which uses the 4-bit digital data output from the DTMF decoder 21 as an address. Of the DTMF oscillator 11 of the transmitter 1 and the receiver 2 having 16 or less bits of memory 22 which uses the detection signal of No. 16 as a write signal, and 16 or less of binary outputs 23 corresponding to each bit of the memory 22. The digital counter 13 includes a pair of transmission lines 3 for connecting the output and the input of the DTMF decoder 21 of the receiving device 2, and the count-up cycle of the digital counter 13 is D
It is characterized in that the TMF decoder 21 is set longer than the time required for recognizing the push button signal.

[Operation] The multiplex transmission device of the present invention has a configuration in which the time division multiplex transmission device and the frequency division multiplex transmission device are eclectic, and the digital counter 13 of the transmission device 1 sets the time axis of the transmission line 3 to 16 times.
The role of dividing into individual time zones and 16 by the scanner 14
It also has the function of cyclically scanning the binary inputs 12 or less. The DTMF transmitter 11 transmits a push button signal when the binary input 12 has a logical value of either "1" or "0". The push button signal has four high frequencies _H1 , _H2 , _H3 ,
Any one of _H4 and four low frequency _{L1
It is composed} of any one of _L2 , _L3 , and _L4 , and can represent 16 states. Since the push button signal transmitted by the DTMF transmitter 11 is determined by the signal obtained by decoding the count value of the digital counter 13 by the decoder 15, the push button signal corresponding to the binary input 12 scanned by the scanner 14 is transmitted. be able to.

In the receiving device 2, the push button signal is decoded by the DTMF decoder 21 to reproduce 4-bit digital data, the digital data is used as an address, the push button signal detection signal is used as a write signal, and a memory of 16 bits or less is used. Binary data of "1" or "0" is written in each bit of 22 and 16 or less binary outputs 2 depending on whether each bit of this memory 22 is "1" or "0"
3 can be obtained.

[Embodiment] FIG. 1 is a block circuit diagram of a transmitter 1 used in an embodiment of the present invention, and FIG. 2 is a block circuit diagram of a receiver 2 used in the same. The transmitter 1 and the receiver 2 are connected by a transmission line 3. As the transmission line 3, for example,
A cable including two signal lines such as a telephone cable or a coaxial cable may be used. Hereinafter, the configurations of the transmitting device 1 and the receiving device 2 will be described in detail.

First, the transmitting device 1 comprises 15 binary inputs 12. As this binary input 12, for example, "open"
Can be in one of a closed state and a "closed" state 15
The contact groups S _{0 to} S ₁₄ are used. Scanner 14 is 1
It is provided with six input terminals I _{0 to} I ₁₅ , of which 1
The input terminals I ₁₅ are connected to the ground level,
The other input terminals I _{0 to} I ₁₄ are respectively connected to the contact groups S _{0 to} S described above.
Connected to ground level through ₁₄ . The input terminals I _{0 to} I ₁₅ are pulled up to “High” level via separate internal resistors. Therefore, if the contact Sn (where n = 0 to 14) is in the "open" state, the contact Sn
The input terminal In corresponding to becomes "High" level, and conversely,
When the contact Sn is in the "closed" state, the input terminal In corresponding to the contact Sn is at the "Low" level. The input terminal I ₁₅ connected to the ground level is always "Low" level.

The 4-bit digital data from the digital counter 13 is input to the scanner 14 as a count value n. The digital counter 13 counts clock pulses having a predetermined cycle, and the count value n is incremented by 1 each time one pulse is counted. This count value n is 15
When it reaches, it returns to 0 and continues to count cyclically. Then, according to the count value n (= 0 to 15) of the digital counter 13, the scanner 14 sets 1
Select one input terminal In from the six input terminals I _{0 to} I ₁₅ and determine whether the input terminal In is at “High” level or “Lo”.
A 1-bit binary signal indicating whether it is at the w "level is taken out to the output terminal 14a.

Next, the decoder 15 inputs the count value n of the digital counter 13 as 4-bit digital data, outputs a signal obtained by decoding the upper 2 bits thereof to the output terminal group 15a, and outputs a signal obtained by decoding the lower 2 bits thereof. Group 15b
Output to. The output terminal group 15a is composed of four signal lines,
When the output terminal 14a of the scanner 14 is at "Low" level, one of the signal lines is at "Low" level and the other 3 depending on the upper 2 bits of the 4-bit digital data output from the digital counter 13. The signal line of the book is "High"
It becomes a level. Similarly, the output terminal group 15b is also composed of four signal lines, and when the output terminal 14a of the scanner 14 is at the "Low" level, according to the lower 2 bits of the 4-bit digital data output from the digital counter 13, Any one of the signal lines becomes "Low" level, and the other three signal lines become "High" level. However, when the output terminal 14a of the scanner 14 is at "High" level, the output terminal groups 15a, 15b
All become "High" level, and the decoding operation of the decoder 15 is prohibited.

Now, the output terminal groups 15a and 15b are connected to the DTMT oscillator 1
They are respectively connected to the first high-frequency selection terminal group H ₁ to H ₄ and low frequency selective terminals L ₁ ~L _4. The DTMF transmitter 11 has four high frequencies of _H1 = 1,209H.
z, _H2 = 1,336Hz, _H3 = 1,477Hz, _H4 = 1,633
Hz are possible outgoing any one, when the other three are in the "High" level in the four high-frequency selection any one of the terminal groups H ₁ to H ₄ "Low" level, four High frequency
Among _H1 to _H4 , one corresponding high frequency is transmitted. Similarly, the DTMF transmitter 11 has four high frequency components _L1 = 697 Hz, _L2 = 720 Hz,
_L3 = _852Hz, L4 = 941Hz is capable transmitting any one of the four low frequency selected any one of the terminal groups L ₁ ~L ₄ "Low" but the other three at level "High" level At this time, one corresponding high frequency among the four low frequencies _L1 to _L4 is transmitted. Therefore, the output terminal 11a of the DTMF oscillator 11 outputs a combination of any one high frequency and any one low frequency. The pushbutton signal composed of the combination of the high frequency and the low frequency is applied to the line amplifier 16
The signal is amplified by the line transformer 17, is further converted by the line transformer 17 from an unbalanced signal into a balanced signal, and is sent out to the transmission line 3.

Next, the configuration of the receiving device 2 will be described. Receiver 2
Then, the balanced signal received from the transmission line 3 is converted into an unbalanced signal by the line transformer 24, and the DTMF decoder 2
Decode by 1. In the DTMF decode 21, when a push button signal is detected at the input terminal 21a, a "Low" level detection signal is output to the output terminal 21b, and 4-bit digital data corresponding to the push button signal is decoded at the output terminal D _0. ~ Output to D ₃ .

Here, at least 40 msec is required for the DTMF decode 21 to recognize the push button signal. Therefore, in this embodiment, in order to improve the transmission reliability, the count-up cycle of the digital counter 13 in the transmitter 1 is set to about 100 msec.

Decode output terminals D _{0 to} D _{3 of the} DTMF decoder 21.
Are address input terminals A ₀ to A of the 15-bit memory 22.
It is connected to each A ₃ . The memory 22 has 16 addresses designated by the address input terminals A _{0 to} A ₃ , and can store 1-bit binary data at each address. In this embodiment, 15-bit data is output in parallel and is input in parallel to the latch 25 including a group of 15 D flip-flops.

Here, the write timing to the memory 22 and the timing at which the latch 25 latches the data are controlled by the write control circuit 27. The decode output of the DTMF decoder 21 and the detection signal of the push button signal are input to the write control circuit 27, and the scanner 14 in the transmitter 1 receives the input terminals I ₀ to I ₀ to.
When a push button signal that should have been sent while scanning I ₁₄ is detected, a write signal is given to the write terminal W of the memory 22 so that the address is designated by the decode output of the DTMF decoder 21. Write the data of "1". Further, when the push button signal that should be sent while the scanner 14 in the transmitter 1 is scanning the input terminal I ₁₅ is detected, a latch timing pulse is given to the latch 25 and written in the memory 22. 15 bits of data are simultaneously latched, and after the latch is completed, a reset signal is applied to the reset terminal R of the memory 22 to set all bits of the memory 22 to "0".

By cyclically repeating the above operation, the output of the latch 25 is "0" corresponding to the "open" state or the "closed" state of the 15 contact groups Sn which are the binary input 12 of the transmitter 1. A 15-bit binary signal having a logical value of "" or "1" is obtained. This signal is amplified by 15 drivers 26, respectively, and the open collector transistors Qn (n = 0 to 14) are driven to obtain 15 binary outputs 23. The latch timing pulse to the latch 25 is slightly delayed by the delay circuit 28 and output as a strobe signal via the driver 29. The external control device or the external display device connected to the receiving device 2 may read the binary output 23 in synchronization with the timing of the strobe signal.

The DTMF decoder 21 used in the receiving device 2
Is an IC developed for telephone lines, it has a function of superposing a DC voltage between a pair of transmission lines 3. Therefore, the transmitter 1 can be supplied with power from the transmission line 3, and it is not necessary to separately prepare a power supply circuit.

In the above embodiment, one of the 16 push button signals is used as the synchronization signal, so only 15 signals can be transmitted. However, for example, as in the abnormality monitoring device, each contact is normally operated. It is not necessary to reset the memory 22 in an application in which all the contacts are in the "open" state and the contacts corresponding to the abnormal location are in the "closed" state only when an abnormality occurs, so that it is possible to transmit 16 signals. Become.

[Advantages of the Invention] According to the present invention, as described above, the DTMF oscillator for transmitting the push button signal composed of the combination of the first to fourth high frequencies and the first to fourth low frequencies. Is provided in the transmitting device and the DTMF decoder for decoding the push button signal is provided in the receiving device. Therefore, 16 or less control states and monitoring states can be transmitted through a pair of transmission lines although the configuration is relatively simple. It has been proven that multiplex transmission is possible, and that the push-button signal transmission / reception circuit shows stable transmission characteristics in the telephone line, so there is very little possibility of malfunction and high reliability is obtained. There is an effect that is.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of a transmitter used in an embodiment of the present invention, and FIG. 2 is a block circuit diagram of a receiver used therein. 1 is a transmitter, 2 is a receiver, 3 is a transmission line, and 11 is DT
MF oscillator, 12 binary input, 13 digital counter, 14 scanner, 15 decoder, 21 DTM
An F decoder, 22 is a memory, and 23 is a binary output.

Claims (1)

[Scope of utility model registration request] 1. A first to fourth high frequency selection terminal and a first
To a fourth low frequency selection terminal, and a DTMF oscillator for transmitting a push button signal composed of a combination of any one high frequency and any one low frequency, and 16 or less binary inputs, A 4-bit digital counter that counts up in a predetermined cycle, a scanner that scans the state of a binary input specified by the count value of the digital counter, and a binary input that is scanned by the scanner is "1" or "0". A transmitter including a decoder that decodes the count value of the digital counter so that one high-frequency selection terminal and one low-frequency selection terminal of the DTMF oscillator become active when the logical value is one of the two. And decode push button signal to output 4-bit digital data and detect push button signal A DTMF decoder that outputs a signal, a memory of 16 bits or less that uses the 4-bit digital data output from the DTMF decoder as an address and a push button signal detection signal as a write signal, and 16 bits corresponding to each bit of the memory The digital counter comprises: a receiving device having the following binary output; and a pair of transmission lines connecting the output of the DTMF oscillator of the transmitting device and the input of the DTMF decoder of the receiving device. , DTM
A multiplex transmission device characterized in that the F decoder is set to be longer than the time required to recognize a push button signal.