JPH0642676B2 - Multiplexer - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention connects a primary station (master station) and a plurality of transmission / reception-type secondary stations (slave stations) with a dedicated two-core wire in a digital chain loop connection. The present invention relates to a configured multiplex transmission device.

[Outline of Invention]

The multiplex transmission apparatus according to the present invention sends a polling signal at the time of sending data from the primary station to the secondary station, sends a data signal to each secondary station at predetermined intervals, and sends a polling signal at the time of receiving data from the secondary station. To send data to each secondary station, and a secondary station that receives a data signal from the primary station and sends data to the polling signal. It is a loop connection to. With such a configuration, it is not necessary to set an address for each secondary station, and it is possible to form a multiplex transmission device by connecting secondary stations having a transmission / reception function.

[Prior art and its problems]

Generally, in a multiplex transmission device that configures a data transmission system by connecting a primary station and a plurality of secondary stations with a two-core dedicated line, the secondary station is connected to an arbitrary point on a common bus. The multi-drop method is often used, and in this case 2
It is necessary to set a unique address for each next station. Such address setting is normally done by the DIP provided in each secondary station.
It is set by a switch or the like.

However, when the secondary station needs to be extremely miniaturized, there is a problem that the miniaturization is restricted by the DIP switch. When a large number of secondary stations are installed at a time, it is relatively easy to set the addresses, but when the number of secondary stations is increased or decreased after the system configuration of the multiplex transmission device, the addresses may not be continuous. Moreover, there is a possibility that a plurality of secondary stations may be erroneously set to the same address, resulting in a transmission error. Also, in order to facilitate the work at the installation site of the secondary station, there is also known a shift register system that does not specify an address to each secondary station. In this system, a signal line for a clock signal is provided in addition to a data signal. There is a problem in that the price of the transmission cable rises because the transmission system cannot be constructed using the inexpensive two-core wire, which is necessary. The secondary station has a reception type secondary station that receives data from the primary station and drives a relay and the like, and a transmission type secondary station that sends signals of sensors and the like to the primary station, but these are shared. I couldn't.

[Object of the Invention]

The present invention has been made in view of the above problems of the conventional multiplex transmission device, and two DIP switches are used.
It is an object of the present invention to provide a multiplex transmission device which does not need to set an address in a next station and can configure a system using a secondary station having both transmitting and receiving functions.

[Constitution and effect of the invention]

The present invention has a primary station and a plurality of secondary stations, and the output terminal of the primary station is the input terminal of the secondary station with the highest priority, and the output terminal of each secondary station is the secondary with the second priority. It is connected to the input terminal of the station and the last 2
A multiplex transmission apparatus configured by connecting an output end of a next station to an input end of the primary station, wherein the primary station is a data receiving mode,
Polling signal transmitting means for transmitting a polling signal which becomes a transmission / reception right to the secondary station having the highest priority when switching the data transmission mode, and data for each secondary station after transmitting the polling signal from the secondary station having the highest priority. A data transmission means for sequentially and intermittently transmitting data at predetermined intervals (t), a start signal transmission means for transmitting a start signal for setting the secondary station in the data transmission mode after the data transmission means, and a start signal. After sending the start signal and the polling signal from the sending means and the polling signal sending means, each 2
Data receiving means for sequentially receiving the data given from the next station, and each secondary station is connected between the input and output terminals and allows the data signal and the start signal obtained from the input terminal to pass through and cuts off the polling signal. Filter means, mode storing means for receiving a start signal and storing a data transmission mode, data signal receiving means for receiving a data signal given after reception of a polling signal in the data reception mode, and data transmission mode Data sending means for sending data to the primary station after receiving the polling signal, and to the secondary station in the lower order so that the sending is completed within a predetermined interval (t) after the data signal is received by the data signal receiving means. A polling signal transmitting means for transmitting a polling signal and transmitting the polling signal after the data transmitting means transmits the data signal. And it is characterized in Rukoto.

According to the present invention having such characteristics, the polling signal, the start signal and the data signal are transmitted using the two-core transmission line, and each secondary station receives the data after receiving the polling signal in the data reception mode. Is used as the data for the own station, and then the polling signal is issued by itself to give the polling signal to the secondary station of the next rank. When the start signal is given, the data transmission mode is entered, and the station transmits data to the polling signal to transmit data to the primary station. With such a configuration, it becomes possible to perform data transmission between a plurality of secondary stations having an input / output function and the primary station using only the two-core transmission line. Since no address is set for each secondary station, it is not necessary to provide a DIP switch. Therefore, each secondary station can be downsized, and workability at the time of installing the secondary station can be improved. 1 more
Since the start signal, the polling signal transmitted from the secondary station, and the data signal on the line can be monitored on the side of the next station, it is possible to detect the broken secondary station and the location of disconnection of the transmission line.

[Explanation of Examples]

FIG. 1 is a schematic block diagram showing an embodiment of a multiplex transmission apparatus according to the present invention. In this figure, the primary station 1 and a plurality of 2
The secondary stations 2, 3 and 4 are loop-connected in a digital chain by a two-core transmission line 5. That is, the output terminal 1-o of the primary station
Is connected to the input terminal 2-i of the secondary station 2 connected in the highest order, and the output terminal 2-o of the secondary station 2 is connected by the transmission line 5 to the input terminal 3-i of the secondary station 3 of the next order. It is connected to the. Similarly, the output terminal 3-o of the secondary station 3 is the input terminal 4-i of the secondary station 4 of the last rank, and its output terminal 4-o is the input terminal 1 of the primary station 1 via the transmission line 5. -i is connected. The primary station 1 intermittently and sequentially sends a polling signal for transmitting a data signal to a secondary station connected in a loop, and a data signal and a start signal for transmitting to the secondary stations 2, 3 and 4.

(Structure of Primary Station) As shown in the structure of FIG. 2, the primary station 1 is reset by a polling signal transmission circuit 11, a polling signal monitoring timer 12 that operates based on a start signal from the outside, and a start signal. It has a re-transmission flag 13 and a disconnection flag 14. The polling signal transmission circuit 11 is supplied with an output of an oscillator 15 that oscillates a frequency of the polling signal, for example, a frequency of 1 MHz, transmits a polling signal in response to a start signal, and transmits the transmission timing to the data signal transmission circuit 16. . The data signal transmission circuit 16 is a transmission circuit that sequentially transmits data for each secondary station set from the outside by, for example, bi-phase code, and the data signal timer 17 is reset at each transmission. The data signal timer 17 is a timer for setting the transmission timing of the data signal, and transmits a time-up signal to the data signal transmission circuit 16 every time the time is up, and based on this, the data signal transmission circuit 16 sends data to each secondary station. Are sequentially transmitted. The input terminal 1-i of the primary station 1 is provided with a polling signal detecting circuit 18 and a start signal receiving circuit 19 for receiving a polling signal from the secondary station 4 connected last. The polling signal detection circuit 18 receives the polling signal from the secondary station of the last rank and resets the polling signal monitoring timer 12,
Alternatively, the data signal receiving circuit 20 and the polling signal transmitting circuit 11 are alternatively operated. The polling signal monitoring timer 12 monitors a polling signal given from the last station in each cycle of data transmission and reception, and gives its output to the data signal receiving circuit 20 and the start signal transmitting circuit 21. The start signal transmission circuit 21 is a transmission circuit for transmitting a biphase signal having a frequency of, for example, 60 KHz and 30 KHz to the respective secondary stations at the beginning of the data reception cycle of the primary station 1, like the data signal. The transmission timing of the start signal transmitting circuit 21 is given to the start signal receiving circuit 19,
At that time, if the start signal is not received via the transmission line 5, the disconnection flag 14 is set. The data signal receiving circuit 20 receives the data signal of each secondary station transmitted from the output terminal 1-o, and applies the received signal to the data reproducing circuit 22 to reproduce the data and output it to the outside. The data counter 23 is a counter for counting the number of received data, and the count value is given to the abnormality processing unit 24. Further, the outputs of the polling signal monitoring timer 12, the disconnection flag 14, and the retransmission flag 13 are given to the abnormality processing unit 24. The abnormality processing unit 24 uses each of the two inputs as described below based on these inputs.
It is a detection processing unit that detects disconnection of the transmission line 5 between the next station and the next station.

(Structure of Secondary Station) FIG. 3 is a block diagram showing the structure of the secondary station 2, but the other secondary stations 3 and 4 have the same structure. At the input terminal 2-i of the secondary station 2, a low pass filter 31, a start signal detection circuit 32, and a polling signal detection circuit 3 are provided.
3 and the data signal receiving circuit 34 are connected. The low-pass filter 31 is a passive filter composed of LC,
A signal with a frequency of 1 MHz used as a polling signal is cut off, and a frequency of 1 MHz or less transmitted from the transmission line 5,
For example, the data signal and the start signal modulated at 60 KHz and 30 KHz are directly transmitted to the output terminal 2-o. Further, the start signal detection circuit 32 detects the start signal given from the transmission line 5 and sets the output flag 35. The output flag 35 is a flag for storing the transmission / reception mode, and the polling signal detection circuit 33 receives the polling signal given through the transmission line 5 and gives the detection timing to the data signal reception circuit 34. The data signal receiving circuit 34 receives the data signal immediately after the polling signal is received in the reception mode in which the output flag 35 is not set, and gives its output to the data signal reproducing circuit 36. The data signal reproduction circuit 36 decodes the data signal sent from the primary station 1 and outputs it as a data signal, and its output is used as a drive signal for different output means such as a relay for each secondary station. To be The reception timing of the data signal receiving circuit 34 is given to the polling signal transmitting circuit 37. The polling signal transmission circuit 37 is a transmission circuit for transmitting a polling signal from the secondary station 2 itself to the secondary station in the lower order, and is connected to an oscillator 38 having a frequency of 1 MHz used for generating the polling signal. The data signal transmission circuit 39 is a circuit for transmitting a data signal to be transmitted to the primary station 1 after receiving the polling signal in the data transmission mode in which the output flag 35 is set. Give to. Then, the low-pass filter 31, the polling signal transmission circuit 37, and the data signal transmission circuit 39
Is connected to the secondary station 3 in the rear order via the output terminal 2-o.

(Operation of the present embodiment) Next, the operation of the present embodiment will be described with reference to the flowchart and the waveform diagram. FIG. 4 is a flow chart showing the operation of the primary station 1, FIG. 5 is a flow chart showing the operation of each secondary station, and FIGS. 6 (a) to 6 (d) are a to FIG.
It is a wave form diagram which shows the signal waveform of each point of d. In the figure, when a start signal is given to the primary station 1, the operation is started, and first the process proceeds to step 41 in FIG. 4 to reset the retransmission flag 13 and the disconnection flag 14. Then, in step 42, the polling signal monitoring timer 12 is activated, and the process proceeds to step 43, in which the polling signal transmitting circuit 11 is operated as shown in FIG.
As shown in (a), the polling signal P1 is transmitted. As described above, the polling signal has a frequency of 1M for a predetermined period.
A Hz signal shall be transmitted. And then the routine
Proceeding to 44, the data signal transmitting circuit 16 intermittently connects and disconnects the data signals D2r, D3r, D4r to the respective secondary stations 2, 3 and 4 at predetermined intervals t as shown in FIGS. 6 (a) to (d). To send out.

When the secondary station 2 starts its operation, it resets the output flag 35 in step 71, and checks in steps 72 and 73 whether the start signals and polling signals are detected by the detection circuits 32 and 33. If the polling signal P1 is detected in step 73 prior to the detection of the start signal, the process proceeds to step 75 and the output flag 3
Check if 5 is standing. If this flag is not set, it is operating in the data reception mode as shown in the time zone Tr of FIG. 6, so the routine proceeds to step 76, where the data signal D2r given from the data signal reception circuit 34 through the transmission line 5 is supplied. To receive. Then, after receiving the data, the polling signal transmitting circuit 37 sends the polling signal P2.
Is generated and sent from the output terminal 2-o as shown in FIG. 6 (b) (step 77). Here, the data signal D2r is shown in FIG.
As shown in (a) to (d), the secondary signal passes through the low-pass filters of the secondary stations 2 to 4 and returns to the primary station 1, but the polling signal P
The data is valid only for the secondary station 2 to which 1 is given. After transmitting the polling signal, the secondary station 2 returns to step 72 and repeats the same processing thereafter. By doing this, as shown in FIG. 6, by selecting the data transmission timing t to an appropriate value, the polling signals P2, P3, P4 generated by each secondary station are added to the data given from the primary station 1. It is possible to overlap and transmit data to the respective secondary stations 2 to 4.

By the time the polling signal monitoring timer 12 expires, the polling signal receiving circuit 18 sets the last 2
When the polling signal P4 is received from the next station 4, the routine proceeds to step 46 through step 45, and the polling signal monitoring timer 12 is reset. If the polling signal monitoring timer times out within this period, the process proceeds to step 48 through step 47 without performing this processing, and the polling signal monitoring timer 12 is operated again. Then, in step 49, the data counter 23 is reset, and in step 50, the start signal transmitting circuit 21 transmits the start signal S1 as shown in FIG. 6 (a). The start signal S1 has a frequency of 60 KHz and 30 as with the data signal as described above.
Since it consists of KHz bi-phase code, each 2
It passes through the low-pass filters of the secondary stations 2 to 4 as they are and returns to the input terminal 1-i of the primary station 1 via the transmission line 5. Therefore, in step 51, it is checked whether or not the start signal is received from the start signal receiving circuit 19, and if the start signal is not received, there is a disconnection in any of the transmission lines 5, so the disconnection flag 14 is set (step 52), and the start If a signal is detected, the process proceeds to step 53 without performing this process, and the polling signal detection circuit 18 gives a start signal to the polling signal transmission circuit 11 to send the polling signal P.
Send 1. Then, in steps 54, 55 and 56, the polling signal and the data signal are detected until the polling signal monitoring timer 12 times out.

On the other hand, in the secondary station 2, in step 72, the start signal S1
Is detected, the output flag 35 is set (step 73),
The data transmission mode is entered and the presence or absence of a polling signal is monitored. After that, if the polling signal is detected, the output flag 35 is set. Therefore, the process proceeds to step 78 through step 75, and the data D2s to be transmitted from the secondary station 2 to the primary station 1 is transmitted by the data signal transmission circuit 36. This data signal is the same as the data sent from the primary station 1 to each secondary station.
Since it consists of KHz and 30 KHz signals, it passes through the low-pass filter 31. Therefore, as shown in FIGS. 6 (a) to 6 (d), this signal can be detected at all points on the transmission line 5. Therefore, the primary station 1 receives this data by the data signal receiving circuit 20 connected to its output terminal 1-o. Then, the process proceeds to step 79 and the output flag 35
, And returns to step 77 to send the polling signal P2 to the secondary station 3 as in the reception mode described above. By doing so, as shown in FIGS. 6 (b), (c), and (d), it is possible to transmit a polling signal which becomes a transmission / reception right to each secondary station in order to collect data to the primary station. When the primary station 1 receives the data signal, it proceeds to steps 57 and 58 via step 55 to increment the data counter 23, outputs the data of the secondary station of the counted value from the data reproduction circuit 22, and proceeds to step 54. Return. If the polling signal P4 is given from the secondary station 4 of the last rank, the data transmission mode of the secondary station has ended, so that the process returns from step 54 to step 41 and the same processing is repeated thereafter.

However, the polling signal monitoring timer may time out without being given the polling signal. In this case, the process proceeds from step 56 to step 59 to check whether the retransmission flag 13 is set. Since the retransmission flag 13 is initially reset, the routine proceeds to step 60, where the retransmission flag 13 is set, and the routine returns to step 49 to repeat the same processing. If there is any abnormality, the polling signal monitoring timer 12 times out before the polling signal is detected again. Therefore, the process proceeds to step 61 through step 59 to check whether the disconnection flag 14 is set. When the disconnection flag 14 is set, data has been normally transmitted up to the secondary station having the count value indicated by the data counter 23, so the count value (CN)
Since it can be identified that the transmission line 5 is disconnected between the secondary stations of (CN + 1) and (CN + 1), the process proceeds to step 62 and the abnormality processing unit 24
Output more disconnection. If the disconnection flag 14 is not set, the secondary station (CN + 1) in the subsequent rank of the count value (CN)
Is judged to be defective (step 63),
The abnormality processing unit 24 outputs a message to that effect and ends the processing.

In this way, the primary station 1 sends the polling signal and then sequentially sends the data to each secondary station at a predetermined timing, and also sends the start signal and the polling signal and then sends the data from each secondary station. The polling signals generated by each secondary station upon reception are superposed in between,
Data can be exchanged without setting an address for the next station.

Although the present embodiment has described the multiplex transmission device using three secondary stations, it is needless to say that a similar system can be configured by using a larger number of secondary stations. Further, in this embodiment, a low-pass filter is provided to pass the data signal and the start signal to each secondary station as they are and to cut off only the polling signal. However, a low-frequency signal is used as the polling signal to modulate the data signal at a high frequency. It is also possible to change the filter for passing the data signal and the start signal to another filter such as a high pass filter.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an embodiment of a multiplex transmission apparatus according to the present invention, and FIG. 2 is a block diagram of a multiplex transmission apparatus according to the present invention.
FIG. 3 is a block diagram showing the configuration of the secondary station 1, FIG. 3 is a block diagram showing the configuration of the secondary station, FIG. 4 is a flowchart showing the operation of the primary station 1, and FIG. 5 is an operation of the secondary station 2. A flow chart, FIG. 6 is a waveform diagram showing the waveform of each part a to d of the transmission line of the multiplex transmission device. 1 ... Primary station, 2, 3, 4 ... Secondary station, 5 ... Transmission line,
11, 37 ... Polling signal transmitting circuit, 12 ... Polling signal monitoring timer, 16, 39 ... Data signal transmitting circuit, 18, 33 ... Polling signal detecting circuit, 19 ...
... Start signal receiving circuit, 20, 34 ... Data signal receiving circuit, 21 ... Start signal transmitting circuit, 24 ... Abnormality processing section, 31 ... Low pass filter, 32 ... Start signal detecting circuit, 35 ... Output flag

Claims (2)

[Claims] 1. A primary station and a plurality of secondary stations, wherein the output terminal of the primary station is the input terminal of the secondary station having the highest priority, and the output terminal of each secondary station is the secondary order. A multiplex transmission apparatus configured to be connected to an input terminal of a secondary station, and an output terminal of the last-ordered secondary station connected to an input terminal of the primary station, wherein the primary station is a data reception mode, Polling signal transmitting means for transmitting a polling signal which becomes a transmission / reception right to the secondary station having the highest priority when the data transmission mode is switched, and data for each secondary station after the polling signal is transmitted from the secondary station having the highest priority. Data transmission means for transmitting intermittently in sequence at a predetermined interval (t), and start signal transmission means for transmitting a start signal for placing the secondary station in the data transmission mode after the data transmission from the data transmission means. , The start signal transmitting means and polling Each After sending a from start signal and a polling signal No. sending means 2
Data receiving means for sequentially receiving data given from the next station, wherein each of the secondary stations is connected between the input and output terminals and allows a data signal and a start signal obtained from an input terminal to pass through and cuts off a polling signal. Filter means, a mode storage means for receiving a start signal and storing a data transmission mode, a data signal reception means for receiving a data signal given after receiving a polling signal in the data reception mode, and a data transmission mode Sometimes 1 after receiving a polling signal
Data sending means for sending data to the next station, and a polling signal is sent to the secondary station in the next order so that the sending is completed within the predetermined interval (t) after the data signal is received by the data signal receiving means. And a polling signal transmitting means for transmitting a polling signal after the data signal is transmitted by the data transmitting means. 2. The polling signal transmitted by the polling signal transmitting means of the primary station and each of the secondary stations is a signal having a frequency higher than that of the data signal and the start signal, and the filtering means of each of the secondary stations is A low-pass filter for blocking the polling signal and passing a data signal and a start signal.
The multiplex transmission device according to the item.