JPH03828B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a master station device for a remote monitoring and control system that can simultaneously perform data communication and telephone communication using a maintenance telephone using a frequency division method. The present invention relates to a maintenance telephone control circuit for enabling a telephone conversation between two slave stations including the slave station in progress while the master station is talking to one slave station.

[Prior Art] FIG. 2 is a block diagram for explaining an overview of a remote monitoring and control system. In the figure, A is a master station device comprising a control circuit 1, a line interface circuit 2, a modem (modulation/demodulation circuit) 3, a control circuit 4, etc. of the telephone T, and B ₁ to _{B 4} are slave stations.

That is, the master station device A is connected to the four slave stations B ₁ to _{B 4} via transmission lines, and in order to perform data communication and telephone communication at the same time, the master station device A is connected to the signals of the data communication modem and the maintenance telephone. In order to separate the sound from the sound, high-pass filter HP1~
HP4 and low pass filters LP1 to LP4 are provided, respectively. Note that S is a selection switch.

These filters are required in accordance with the number of slave stations; for example, when there are two slave stations as shown in FIG. 3, four high-pass filters and four low-pass filters are provided. Note that FIG. 3 is a configuration diagram showing a conventional example of a master station device. Here, S ₁₁ and S ₁₂ and
S ₂₁ and S ₂₂ are switches that operate in conjunction with each other, and the rest are the same as those shown in FIG. 2.

[Problem to be solved by the invention] In other words, in the above configuration, filters are required to support the slave stations (generally, if the number of slave stations is n, then 2n filters), so the higher the number of slave stations, the higher the cost. There is a problem in that the number of filters increases accordingly, resulting in higher costs. In addition, in the configuration shown in FIG. 3, when the master station is talking to one of the slave stations, for example, _B1 (parent-child conversation), the slave station _B1
There is also the problem that calls between B4 and _B4 (calls between slave stations) are not possible.

Therefore, it is an object of the present invention to provide a maintenance telephone control circuit that can reduce costs by particularly reducing the number of low-pass filters, and can simultaneously perform parent-child calls and calls between slave stations. do.

[Means for solving problems]

A branch circuit that branches signals between each slave station and the modem to a maintenance telephone, a detection circuit that detects a calling signal of each slave station from the branched signals, and a first communication circuit for making calls between parent and child. , a second communication circuit for carrying out a communication between any two slave stations, and an addition circuit for adding the outputs of each communication circuit.

[Effect]

By inserting a low-pass filter after the selection switch, it is not necessary to increase the number of filters as the number of slave stations increases, and the output of the first and second communication circuits and each of these circuits can be By providing an adding circuit for addition, calls between parent and child and calls between slave stations can be performed simultaneously.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention, and this is an example in which there are three slave stations. In addition, in the same figure, 11 is a branch circuit consisting of an operational amplifier and an arithmetic unit, etc., 12 is an adder circuit including an operational amplifier,
13 is a calling signal detection circuit, _S11 to _S32 are switches,
LP1 to LP4 are low pass filters, and the others are the same as in FIG. 2 or 3. Note that the high-pass filter is not shown here because the modem 3 has that function. Also, switch
It is assumed that S ₁₁ and S ₁₂ , S ₂₁ and S ₂₂ , and S ₃₁ and S ₃₂ operate in conjunction with each other.

Data signals are transmitted between the modem 3 and the slave stations _B1 to _B4 , while voice signals are transmitted between the maintenance telephone T and the slave stations. Now, when switches S ₁₁ and S ₁₂ are set to the positions shown in the figure and slave station B ₁ is selected, the transmission signal from telephone T passes through low-pass filter LP 1 , switch S ₁₁ and adder circuit 12 and enters branch circuit 11 .
Here, it is added to the output of modem 3 and sent to slave station _B1 . On the other hand, the transmission signal from slave station _B1 is received by telephone T from branch circuit 11 through switch _S12 and low-pass filter LP4. In this way, parent-child communication is performed. Note that the calling signal from the slave station to the master station is constantly monitored by the detection circuit 13, so that the master station can know which slave station has issued the calling signal.

Next, during the parent-child call as described above, slave station 2 and slave station 3
To make a call between the parties, set switches S ₂₁ and S ₂₂ to the positions shown to select slave station B ₃ , and set switches S ₃₁ and S ₃₂ to the positions shown to select slave station B _2. do. As a result, the transmission signal of slave station B ₂ is sent to switch S ₃₁ , low-pass filter LP 2, and switch
S ₂₁ , the adder circuit 12 and the branch circuit 11 to the slave station B ₃ , while the transmission signal of the slave station B ₃ is sent to the switch S ₂₂ , the low-pass filter LP 3 and the switch
S ₃₂ , is sent to the slave station B ₂ via the adder circuit 12 and the branch circuit 11. In this way, even during a call between the slave station _B1 and the master station, a call can be made between the slave station _B2 and the slave station _B3 .

Similarly, by switches S ₁₁ and S ₁₂ , slave stations B ₂ ,
If B ₃ is selected, slave stations B ₂ and B ₃ can talk to slave station B ₁ as well as to the master station. Furthermore, while slave station B ₁ and the master station are talking, slave station B ₁
If you want to talk to _B2 , notify the master station to that effect, and from the master station switch switches S ₂₁ and S ₂₂ as shown in the dotted lines (other switches S ₁₁ , S ₁₂ , S ₃₁ ,
( _S13 may remain as shown in the figure), and the same applies to slave station _B3 .

In addition, low-pass filters LP1 to LP4 are shown here.
Although four filters are provided, this has nothing to do with the number of slave stations and the number of filters does not change even if the number of slave stations increases, so it can be said that the effect increases as the number of slave stations increases.

〔Effect of the invention〕

According to this invention, only four low-pass filters are required, two for parent-child calls and two for calls between slave stations, so in a system with dozens of slave stations,
The number of filters can be significantly reduced compared to the conventional circuit which requires (number of slave stations) x 2 filters. In this case, each switch needs to have terminals equal to the number of slave stations, but since these are cheaper and smaller than filters, it is possible to make the circuit cheaper and smaller than conventional circuits. is possible. Furthermore, in this invention, the parent-child communication circuit and the communication circuit between slave stations are independent, and the parent-child communication circuit and the communication circuit between slave stations can be performed at the same time. The inconvenience of not being able to use it will not occur.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of this invention;
This figure is a block diagram for explaining the outline of a remote monitoring and control system, and FIG. 3 is a block diagram showing a conventional example of a master station device for a remote monitoring and control system. Explanation of symbols, 1... Telephone control circuit, 11... Branch circuit, 12... Addition circuit, 13... Ringing signal detection circuit, 2... Line interface circuit, 3...
Modem, 4... Control circuit, A... Master station, B ₁ to _{B 4}
...Slave station, T...Telephone, HP1 to HP4...High pass filter, LP1 to LP4...Low pass filter, S, _S11 to _S32 ...Switch.

Claims (1)

[Claims] 1. A frequency division method comprising at least a modem for performing data communication with a plurality of slave stations and a maintenance telephone for performing telephone communication with the plurality of slave stations. A master station device for a remote monitoring and control system capable of simultaneously carrying out data communication and telephone communication in a remote monitoring and control system, comprising: a branch circuit that branches signals between each of the slave stations and the modem to a maintenance telephone; a detection circuit for detecting the calling signal of each slave station from the detection circuit; a first communication circuit that includes a low-pass filter and a selection switch and selects a corresponding slave station from the detection power to perform a call between the parent and child; a second communication circuit that includes a range filter and a selection switch and distributes the branch signal corresponding to one slave station to any other slave station to conduct a call between any two slave stations; an adder circuit for adding the outputs of two call circuits; A telephone control circuit for maintenance use, which is characterized in that it enables the following functions.