JPS61237551A - Multiplex transmission equipment - Google Patents

Abstract

PURPOSE:To simplify the circuit by adding the return of data signal which is sent against the trigger signal of the secondary station from the primary station which is connected in loop with plural number of secondary stations to the counter at each cycle of data transmission, and detecting abnormality. CONSTITUTION:Plural number of secondary stations 2-4 are connected in loop to a primary station 1 by a two-core transmission cable. The primary station outputs a polling signal and a trigger signal from its output terminal 1-0. When the trigger signal is detected at its input terminal 1-i, a data signal is send to the secondary stations. Number is added to the counter at each action cycle of data transmission, if the data does not return to the primary station, or if a prescribed time signal is not obtained, it is judged as abnormal, and abnormal processing is done. The secondary station sends the trigger signal if the poling signal is addressed to it, and demands data against the primary station and receives the data. After the action of the secondary station is over, the poling signal is transferred sequentially to lower stations. Thus, setting of address becomes unnecessary, and multiplex transmission can be done by simple circuits.

Description

[Detailed Description of the Invention] [Field of the Invention] The present invention is constructed by connecting a primary station (master station) and a plurality of secondary stations (slave stations) in a digital chain manner using a dedicated two-core wire. The present invention relates to a multiplex transmission device, and particularly relates to a multiplex transmission device that can detect a disconnection of a transmission line or an abnormality in a secondary station.

[Summary of the invention]

The multiplex transmission device according to the present invention includes a primary station that transmits data to each secondary station every time a trigger signal is received after transmitting a polling signal that is a transmission/reception right, and a loop continuously connected to the primary station in a digital chain manner. A plurality of secondary stations are connected to each other and receive a polling signal from a higher ranking station, send out a trigger signal, receive data from the primary station, and send a polling signal to a lower ranking station. The primary station recognizes the abnormal state of the secondary station by detecting the address of the secondary station that is transmitting data.

Such a configuration eliminates the need to set addresses for each secondary station, making it possible to easily install the secondary stations.

[Prior art and its problems]

In general, in multiplex transmission equipment that configures a data transmission system by connecting a primary station and multiple secondary stations with a two-core dedicated line, the secondary stations are connected to any point on the common bus. A multi-drop system is often used, and in this case it is necessary to set a unique address for each secondary station. Such address settings are normally made using a DIP switch or the like provided at each secondary station.

However, when it is necessary to make the secondary station extremely compact, there is a problem in that the DIP switch limits the miniaturization. Furthermore, when setting up a large number of secondary stations at once, setting addresses is relatively easy, but when increasing or decreasing the number of secondary stations after configuring the multiplex transmission equipment system, the addresses may not be consecutive. Furthermore, there is a possibility that a plurality of secondary stations may be set to the same address by mistake, resulting in a transmission error. In addition, a shift register method is known in which addresses are not specified for each secondary station in order to facilitate work at the site where secondary stations are installed, but this method requires a signal line for clock signals in addition to data signals. Therefore, a transmission system cannot be constructed using inexpensive two-core wires, and there is a problem in that the price of the transmission cable increases. Furthermore, if there is a break in the transmission line connecting the secondary station or if there is an abnormality in the secondary station, it is difficult to easily detect the abnormality.

[Purpose of the invention]

The present invention has been made in view of the problems of the conventional multiplex transmission device, and uses DIP switches to
To provide a multiplex transmission device that does not require setting an address for a next station, can easily detect a disconnection of a transmission cable or an abnormality of a secondary station, and can configure a system using a two-core transmission cable. The purpose is to

[Structure and effects of the invention]

The present invention is a multiplex transmission device in which a primary station and a plurality of secondary stations are loop-connected in a digital chain manner via a transmission line, and the primary station transmits a polling signal, which is the right to transmit and receive, to the secondary station having the highest priority. a polling signal transmitting means for transmitting to the station; a trigger signal receiving means for receiving the trigger signal obtained from the secondary station; a data transmitting means for sequentially transmitting data to each secondary station after receiving the trigger signal; a data counter that is incremented sequentially as data is sent each time;
a disconnection flag that is set when a data signal is not obtained via the transmission line when data is sent by the data sending means;
and an abnormality processing unit that detects an abnormal state based on a data counter and a disconnection flag, and each secondary station is connected between input and output, cuts off the polling signal obtained from the input terminal, and disconnects the trigger signal and data signal. filter means for passing only a polling signal; a receiving means for sequentially receiving a trigger signal and a data signal given after receiving a polling signal; and a receiving means for sequentially receiving a trigger signal and a data signal given after receiving a polling signal; The apparatus is characterized by comprising a polling signal sending means for sequentially sending out polling signals.

According to the present invention having such characteristics, a polling signal, a trigger signal, and a data signal are transmitted using a two-core transmission line, and the primary station receives the trigger signal and sends the data signal to the secondary station. After receiving the polling signal, each secondary station sends out a trigger signal to request data from the primary station, and receives the data signal from the primary station. After each secondary station completes its operation, it sequentially transmits a polling signal, which gives it the right to transmit and receive, to secondary stations in subsequent ranks. Therefore, data transmission can be performed reliably. Further, if data is not returned to the primary station or a signal is not obtained for a predetermined period of time, an abnormality processing circuit is used to determine the abnormality. Therefore, it is possible to automatically detect an abnormality in the secondary station or a disconnection state in the transmission line. Such a configuration makes it possible to transmit data to each secondary station using only two-core transmission lines. Further, since no address setting is performed for each secondary station, there is no need to provide a DIP switch. Therefore, each secondary station can be downsized, and workability when installing the secondary stations can be improved.

[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, primary station 1 and multiple 2
The next stations 2, 3, and 4 are loop-connected in a digital chain by a two-core transmission line 5.

In other words, the output terminals 1-0 of the primary station are connected to the first station 2.
The output terminal 2-o of the secondary station 2 is connected to the input terminal 3-i of the next secondary station 3 via a transmission line 5. Similarly, the output terminal 3-o of the secondary station 3 is connected to the input terminal 4-i of the last secondary station 4, and the output terminal 4-0 is connected to the primary station 1 through the transmission line 5.
is connected to input terminals 1-4 of. The primary station 1 sequentially transmits data each time a trigger signal is transmitted to each secondary station connected in a loop, and also detects abnormalities in the secondary stations and the transmission line 5.

(Configuration of Primary Station) As shown in FIG. 2, the primary station 1 includes a polling/trigger signal transmitting circuit 11 that operates based on an external start signal. It has a polling signal monitoring timer 12, a retransmission flag 13 and a disconnection flag 14 that are reset by a start signal. The polling/trigger signal transmitting circuit 11 is supplied with the output of an oscillator 15 that oscillates a signal at a frequency used as a polling signal, for example, IMHz, and transmits a polling signal in response to the start signal, resets the data signal counter 16, and transmits the data. It provides a start signal to the signal transmitting circuit 17. The data signal counter 16 is a counter that counts the address of the secondary station to which data is to be sent, and its output is given to the abnormality processing section 18. The data signal transmitting circuit 17 is a transmitting circuit that sequentially transmits data to each secondary station given from the outside via the multiplexer 19 using, for example, an NRZ code modulated by a signal with a frequency of 60 KHz, and inputs a count every time it is transmitted. is given to the data signal counter 16. A trigger signal detection circuit 20 is also connected to the output terminal 1-o of the primary station 1.

The trigger signal detection circuit 20 detects the trigger signal applied from each secondary station via the transmission line 5, and provides the detection output to the data signal transmission circuit 17, the abnormality processing section 18, and the multiplexer 19.

Further, a data signal detection circuit 2'1 and a polling signal detection circuit 22 are connected to the input terminal 1-i. The data signal detection circuit 21 detects a data signal received from the primary station via the sending transmission line 5, and if no data is detected, a disconnection flag 14 is set. The polling signal detection circuit 22 detects a polling signal applied via the transmission line 5, and supplies the detection output to the outside as a one-scan completion signal, and restarts the operation. The polling signal monitoring timer 12 is a timer set with a time longer than the time required for one scanning to complete data transmission to each secondary station, and performs abnormal processing when no detection input is given from the polling signal detection circuit within this time. It provides a signal to section 18. The abnormality processing unit 18 detects and outputs an abnormality or disconnection state of each secondary station based on the output of the retransmission flag 13, the %7 lag 14, and the output of the poll signal monitor □2.

(Configuration of Secondary Station) FIG. 3 is a block diagram showing the configuration of the secondary station 2, and the other secondary stations 3.4 have similar configurations. Now, a low-pass filter 31 is connected to the input terminal 2-i of the secondary station 2.
A polling signal detection circuit 32 and a trigger data signal reception circuit 33 are connected to the polling signal detection circuit 32 and the trigger data signal reception circuit 33. The low pass filter 31 is L
This is a passive filter consisting of C, which blocks the signal at the frequency IMHZ used as a polling signal regardless of the power supply state, and blocks the signal at the frequency IMH2 given from the transmission line 5.
The following is a filter that directly transmits a data signal modulated by, for example, 60K H2 or a trigger signal to be described later to the output terminal 2-o. Further, the polling signal detection circuit 32 receives the polling signal applied via the transmission line 5, and provides the detection timing to the trigger data signal receiving circuit 33. After receiving the trigger signal, the trigger data signal receiving circuit 33 operates the oscillator 34 and supplies the received data signal to the data signal reproducing circuit 35. The data signal reproducing circuit 35 decodes the data signal sent from the primary station l and outputs it as a data output, and the output is used as a drive signal for different output means, such as a relay, for each secondary station. . Polling trigger signal transmission circuit 3
Reference numeral 6 sends out a polling signal from a trigger data signal receiving circuit to the secondary station connected in the subsequent order based on the data signal reception completion output, and also sends out a trigger signal onto the transmission line 5. The oscillator 34 provides a transmission clock to a polling/trigger signal transmission circuit 36 and a reception clock to a data signal regeneration circuit 35.

(Operation of this embodiment) Next, the operation of this embodiment will be described with reference to flowcharts and waveform diagrams. FIG. 4 is a flowchart showing the operation of the primary station 1, and FIGS.
Figures (a), (b), (d) and (d) are waveform diagrams showing signal waveforms at each point of aw and d shown in FIG.

In these figures, when a start signal is given to the primary station 1, the operation starts, and the process first proceeds to step 41 in FIG. 4, where the retransmission flag 13 and disconnection flag 14 are reset. Then, in step 42, the polling signal monitoring timer 12 starts operating, and in step 43, the polling/trigger signal transmitting circuit 11 sends out the polling signal P1 and the trigger signal T1 as shown in FIG. 5(a). Then, proceeding to step 44, the data signal counter 16
In step 45, the data signal transmitting circuit 17 transmits data D2 to the secondary station 2 as shown in FIG. 5(a). Next, the process proceeds to step 46 where the data signal counter 16 is incremented, and step 47
, it is checked whether the data signal D2 sent here has passed through the transmission line 5 and been detected by the data signal detection circuit 21.If the transmission line A5 is not disconnected, the data signal is passed through the low-pass filter of each secondary station. , and is detected by the data signal detection circuit 21. Therefore, the process advances to step 49 to check whether a polling signal is detected.

Now, the secondary station 2 detects the polling signal P1 by the polling signal detection circuit 32, and then sequentially receives the trigger signal T1 and the data signal D2 from the trigger/data signal receiving circuit 33. The data signal D2 is then reproduced by the data signal reproducing circuit 35 to perform a predetermined operation. Next, the data signal reception completion timing is given to the polling/trigger signal transmitting circuit 36, and as shown in FIG. 5 (bl), a new polling signal P2 is generated and sent from the output terminal 2-o. is sent onto the transmission line 5.

The trigger signal T2 passes through the low-pass filters of the secondary stations 3 and 2 and is detected by the trigger signal detection circuit 20 of the primary station 1. Then step 4 via step 50
Returning to step 5, data D3 for the next secondary station, that is, secondary station 3, indicated by the data signal counter 16 is calculated as shown in FIG.
Send as shown in 8). Then, the same process is repeated, and when the polling signal P4 is transmitted from the last secondary station 4, the process returns from step 49 to step 41, and from then on, the process returns to step 41.
Similar processing is repeated as shown in the figure.

However, the secondary station 3 is out of order and the polling signal P2.
If the secondary station 3 does not send out the trigger signal T3 even if the trigger signal T2 is applied, the process shown in FIG. 6(a) occurs.

As shown in (b) and +d), the primary station 1 cannot receive the trigger signal and repeats the loop of step 49.5 (l and step 51), and at time t3, the polling signal monitoring timer having a time of one scanning or more is activated. 12 times up, the process advances to step 52 to check whether the retransmission flag 13 is set.

At first, retransmission flag 13 is not set, so step 5
In step 3, this flag is set, and the process returns to step 43, whereupon the same process is repeated. If the secondary station 3 is out of order, the trigger signal T3 will not be applied from the secondary station 3, so the process proceeds from step 52 to step 54, where the state of the disconnection flag 14 is checked. If the disconnection flag 14 is not set, the count value of the data signal counter 16 (CN
)+1 is determined to be out of order, so from step 55 the abnormality processing section 18 displays the out of order station using the count value of the data signal counter 16, and the process returns to step 41.

On the other hand, at time t2, as shown in FIG. 5 (do), A5 is transmitted.
If the wire is disconnected, the data signal is not detected at the primary station 1 in step 47, so the disconnection flag 14 is set (
Step 48). And similarly step 49.50
A polling signal and a trigger signal are waited for in the loop of 51 and 51, but the trigger signal passes through the low-pass filter of the secondary station in the priority order and is sent to 1 through the output terminal 1-o of the primary station.
It can be detected by the next station.

Therefore, as shown in Fig. 6(a) and (bl), data transmission is possible up to the station where the disconnection occurs, and data signals are not transmitted to secondary stations connected after the location where the disconnection occurs. Therefore, the process proceeds to step 52 via step 51, and the same process is repeated. If the disconnection flag 14 is set, in step 56, the count value (CN) of the data signal counter 16 is used to connect the secondary station (CN) to (CN+1). )
The process is terminated assuming that the section with is disconnected. Here, as shown in FIG. 6(do), if there is a disconnection during data signal transmission, the disconnection flag 14 may not be set and abnormal processing may be executed. Therefore, as shown in FIG. 4, the retransmission flag 13 is set, the process returns to step 43 via steps 52 and 53, and by repeating the abnormal condition, it is confirmed whether the secondary station is faulty or disconnected, and step 55.
56, abnormalities in the secondary station and disconnection sections are identified and displayed.

In this way, the primary station 1 sends a polling signal and then sequentially sends data to each secondary station, thereby achieving data transmission to the secondary stations. Furthermore, by using the disconnection detection means and the data signal counter of the primary station, it is possible to automatically detect an abnormality or disconnection state of the secondary station in the event of an abnormality.

In this embodiment, a multiplex transmission apparatus using three secondary stations has been described, but it goes without saying that a similar system can be constructed using an even larger number of secondary stations. Furthermore, in this embodiment, a low-pass filter is provided in each secondary station to pass the data signal and trigger signal as they are and block only the polling signal. By modulating the filter, it is also possible to change the filter that blocks only the polling signal to a filter such as a bypass filter.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing an embodiment of a multiplex transmission device according to the present invention, and FIG. 2 is a schematic block diagram showing an embodiment of a multiplex transmission device according to the present invention.
FIG. 3 is a block diagram showing the configuration of the secondary station 1, FIG. 4 is a flowchart showing the operation of the primary station 1, and FIG. 5 shows each part of the transmission line of the multiplex transmission device. a
FIG. 6 is a waveform diagram showing the waveforms of transmission lines a, b, and d of the multiplex transmission device when an abnormal state occurs. 1-・-・-Primary station 2.3.4-・-・-Secondary station
5--・Transmission line 11--・---・Polling・
Trigger signal transmission circuit 12--Polling signal monitoring timer 13--Retransmission flag
14--------- One disconnection flag 16---------
-Data signal counter 17--Data signal transmission circuit 18--Anomaly processing section 20
−・・−・Trigger signal detection circuit 21−−−−−・−
Data signal detection circuit 22 ------- Polling signal detection circuit 31 - Low pass filter 32 ---- Polling signal detection circuit 33
−・−Trigger data signal receiving circuit 35−−−−−
--Data signal regeneration circuit 36--Polling trigger signal transmission circuit Patent applicant Tateishi Electric Co., Ltd. Agent Patent attorney Kanki Okamoto (and one other person) Figure 1 Figure 3 S1 Procedure supplement Original version (spontaneous) 1985 6
May 17th 1, Incident Display 1985 Patent Application No. 078946 2, Title of Invention Multiplex Transmission Device 3, ? Relationship with the case of a person who commits liability Patent applicant address 10 Hanazono Tsuchido-cho, Ukyo-ku, Kyoto-shi, Kyoto Name (294) Tateishi Electric Co., Ltd. Representative Takao Miki 4 Agent address 8550 Nishi-ku, Osaka-shi, Osaka Shinkosan Building 3rd Floor 5, 1-13-38 Nishihoncho, Detailed Description of the Invention Column 6 in the Specification Subject to Amendment, Contents of the Amendment (1) Page 9, Line 15 and Page 11, Line 12 of the Specification row r
The description of 60KHzJ will be corrected to r60KHz and 30KHzJ. (2) The description of ``rNRZ code'' on page 9, line 16 of the specification will be corrected to ``biphase code.''that's all

Claims (2)

[Claims] (1) A multiplex transmission device in which a primary station and a plurality of secondary stations are loop-connected in a digital chain manner via a transmission line, and the primary station transmits a polling signal, which is the right to transmit and receive, to the two stations with the highest priority. a polling signal transmitting means for transmitting to the next station; a trigger signal receiving means for receiving a trigger signal obtained from the secondary station; a data transmitting means for sequentially transmitting data to each of the secondary stations after receiving the trigger signal; a data counter that is sequentially incremented as data is sent out in each operation cycle; a disconnection flag that is set when a data signal is not obtained via the transmission line when the data sending means sends out data; and an abnormality processing unit that detects an abnormal state based on a disconnection flag, and each of the secondary stations is connected between the input and output and cuts off the polling signal obtained from the input terminal, and transmits only the trigger signal and the data signal. a filter means for passing the polling signal; a receiving means for sequentially receiving the trigger signal and the data signal given after receiving the polling signal; and a receiving means for sequentially receiving the polling signal for the subsequent ranking station and the trigger signal for the primary station after the receiving means receives the data signal. A multiplex transmission device comprising: a polling signal transmitting means for transmitting a polling signal; (2) The polling signal sent out by the polling signal sending means of the primary station and each of the secondary stations is a data signal;
Claim 1, wherein the signal has a higher frequency than the trigger signal, and the filter means of each secondary station is a low-pass filter that blocks the polling signal and passes the data signal and the trigger signal. The multiplex transmission device described.