JPS61237548A - Multiplex transmission equipment - Google Patents

Abstract

PURPOSE:To make multiplex transmission with simple lines, by connecting plural number of secondary stations in loop to the primary station, issuing various signals from the primary station and making the secondary station receive/transmit the data only when it received the poling signal addressed to itself. CONSTITUTION:Plural number of secondary stations 2-4 are connected in loop to a primary station 1. The primary station sends out, following the poling signal, state signal and data signal from its output terminal 1-0. The secondary station takes in the poling signal and if the signal is addressed to itself, it receives data signal by the start signal and sends out its own output data to the lower rank station. If the signal is not addressed to itself, it adds the poling signal to the start signal and data signal sent from the higher station to the lower station. By doing so, the address setting for each secondary station becomes unnecessary, and multiple transmission can be done by simple lines.

Description

[Detailed Description of the Invention] [Field of the Invention] The present invention relates to a primary station (master station) and a plurality of transmitting/receiving secondary stations (
The present invention relates to a multiplex transmission device configured by connecting (slave stations) in a digital chain loop using dedicated two-core wires.

[Summary of the invention]

The multiplex transmission device according to the present invention transmits a polling signal when transmitting data from a primary station to a secondary station, and then transmits a data signal to each secondary station at predetermined intervals, and when receiving data from a secondary station, sends a polling signal. The primary station that sends out the data and waits for data from each secondary station, and the secondary station that receives the data signal from the primary station and sends data in response to the polling signal are digitally chained to the primary station. It is connected in a loop. 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 transmitting and receiving functions.

[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 method is often used, in which case 2
It is necessary to set a unique address for each next station. Such address settings are usually done using the DIP installed at each secondary station.
It is set by a switch etc.

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. A shift register method is also known in which addresses are not specified for each secondary station in order to facilitate work at the site where secondary stations are installed. There was a problem in that the transmission system could not be configured using the necessary and inexpensive two-core wire, and the price of the transmission cable increased. In addition, the secondary station includes a receiving type secondary station that receives data from the primary station and drives relays, etc., and a transmitting type secondary station that sends signals such as sensors to the primary station, but these are shared. I couldn't.

[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
It is an object of the present invention to provide a multiplex transmission device that does not require setting an address to the next station and can configure a system using a secondary station that has both transmitting and receiving functions.

[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 connected in a loop in a digital chain manner via a transmission line, and the primary station receives transmission and reception rights when switching between data reception mode and data transmission mode. a polling signal sending means for sending out a polling signal to the highest priority secondary station; a data sending means for sequentially and intermittently sending data to each secondary station after sending the polling signal; Start signal sending means for sending out a start signal to set the secondary station in data sending mode, and after sending the start signal and polling signal from the start signal sending means and the polling signal sending means, sequentially receiving data given from each secondary station. Each secondary station has a filter means connected between the input and output for passing the data signal and start signal obtained from the input terminal and blocking the polling signal, and a filter means for receiving the start signal. mode storage means for storing a data sending mode; data signal receiving means for receiving a data signal given after receiving a polling signal when in a data receiving mode; data transmitting means for transmitting data to a station; polling signal transmitting means for transmitting a boring signal after the data receiving means receives the data signal and after the data transmitting means transmits the data signal;
It is characterized by having the following.

According to the present invention having such characteristics, a polling signal, a start signal, and a data signal are transmitted using a two-core transmission line, and each secondary station receives data after receiving a boring signal in the data reception mode. is used as data for its own station, and then it issues a bowling signal to give a bowling signal to the next secondary station. When a start signal is given, the station enters a data sending mode and transmits data from its own station to the primary station in response to a boring signal. Such a configuration makes it possible to perform data transmission between a plurality of secondary stations having input/output functions and a primary station using only two-core transmission lines.

Also, since addresses are not set for each secondary station, DIP
There is no need to provide a switch. Therefore, each secondary station can be downsized, and workability when installing the secondary stations can be improved. Furthermore, a start signal is sent on the primary station side,
Since the data signal on one polling signal line transmitted from the secondary station can be monitored, it is possible to detect a failed secondary station or a location where the transmission line is disconnected.

[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 2.3.4 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-o is connected to the input terminal 1 of the primary station 1 via the transmission line 5. - connected to i.

The primary station 1 intermittently and sequentially transmits a boring signal that transmits a data signal to a secondary station connected in a loop, and a data signal and a start signal that transmits a data signal and a start signal to the secondary stations 2, 3, and 4.

(Configuration of Primary Station) As shown in FIG. 2, the primary station 1 includes a polling signal transmitting circuit 11. which 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 boring signal transmitting circuit 11 is supplied with the output of an oscillator 15 that oscillates a frequency of a boring signal, for example, IMHz, and transmits a boring signal in response to a start signal and determines the timing of the bowling signal by the data signal transmitting circuit 1.
6.

The data signal transmitting circuit 16 is a transmitting circuit that sequentially transmits data to each secondary station set from the outside using, for example, an NRZ code.
is reset. The data signal timer 17 is a timer that sets the sending timing of the data signal, and transmits a time-up signal to the data signal transmitting circuit 16 every time the time is up, and based on the time-up signal, the data signal transmitting circuit 16 sequentially transmits data to each secondary station. Send. At the input terminal 1-i of the primary station 1, there is a polling signal receiving circuit 18 for receiving a boring signal from the secondary station 4 connected to the last position.
and a start signal receiving circuit 19 are provided. The polling signal receiving circuit 18 receives the bowling signal from the last secondary station, resets or operates the polling signal monitoring timer 12, and selectively operates the data signal receiving circuit 20 and the bowling signal transmitting circuit 11. It is something that makes you The polling signal monitoring timer 12 monitors the bowling signal given from the last ranking station every cycle of data transmission and reception, and provides its output to the data signal receiving circuit 20 and the start signal transmitting circuit 21. The start signal transmitting circuit 21 is a transmitting circuit that transmits an NRZ signal having a frequency of, for example, 60 KHz to each secondary station at the beginning of the data reception cycle of the primary station 1, similar to the data signal. The sending timing of the start signal transmitting circuit 21 is given to the start signal receiving circuit 19, and if the start signal is not received via the transmission line 5 at that time, a 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 supplies 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 that counts the number of received data.
The count value is given to the abnormality processing section 24. Furthermore, a polling signal monitoring timer 12. Disconnection flag 14 and retransmission flag 1
The output of No. 3 is given to the abnormality processing section 24.

The abnormality processing section 24 is a detection processing section that detects a disconnection of each secondary station or the transmission line 5 between them, as described later, based on these inputs.

(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 start signal detection circuit 32, a polling signal detection circuit 33, and a data signal reception circuit 34 are connected. The low-pass filter 31 is a passive filter made of LC, and blocks the IMHz frequency signal used as the boring signal, and cuts off the IMHz frequency signal sent from the transmission line 5.
Hereinafter, a data signal and a start signal modulated at, for example, 60 KHz are transmitted as they are to the output terminal 2-0. Further, the start signal detection circuit 32 detects a start signal applied from the transmission line 5 and sets an 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 boring signal applied via the transmission line 5 and provides its detection timing to the data signal reception circuit 34. The data signal receiving circuit 34 receives the data signal immediately after the boring signal is received in the receiving mode when the output flag 35 is not set, and provides its output to the data signal reproducing circuit 36. The data signal regeneration circuit 36 is the primary station 1
It decodes the data signal sent from the secondary station and outputs it as a data signal, and the output is used as a drive signal for different output means, such as a relay, for each secondary station. The reception timing of the data signal receiving circuit 34 is given to the polling signal transmitting circuit 37. The polling signal transmitting circuit 37 is a transmitting circuit for transmitting a boring signal from the secondary station 2 itself to a subsequent secondary station, and is connected to an oscillator 38 having a frequency of IMHz used for generating the boring signal. The data signal transmission circuit 39 is a circuit that transmits a data signal to be sent to the primary station 1 after receiving a polling signal in the data transmission mode when the output flag 35 is set, and the timing after transmission is determined by the polling signal transmission circuit 37. give to and a low pass filter 31,
Polling signal transmission circuit 37 and data signal transmission circuit 3
9 is connected to the subsequent secondary station 3 via the output terminal 2-o.

(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, FIG. 5 is a flowchart showing the operation of each secondary station, and FIGS. 6(a) to (d) are a-d shown in FIG. FIG. 2 is a waveform diagram showing signal waveforms at each point. In this figure, 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 boring signal monitoring timer 12 is activated, and the process proceeds to step 43, in which the polling signal transmitting circuit 11
From there, a boring signal P1 is sent out as shown in FIG. 6(a). As mentioned above, it is assumed that a signal having a frequency of IMHz is transmitted for a predetermined period of time as a boring signal. Thereafter, the process proceeds to routine 44, where the data signal transmitting circuit 16 sends the data signal D 2 r * to each secondary station 2, 3.4 at predetermined intervals as shown in FIGS. 6(a) to FD1.
D 3 r + D 4 r + are sent intermittently in sequence.

Now, when the secondary station 2 starts operating, it resets the output flag 35 in step 71, and checks in steps 72 and 73 whether or not the start signal and the boring signal are detected by the detection circuits 32 and 33.

If the polling signal P1 is detected in step 73 prior to detection of the start signal, the process proceeds to step 75 to check whether the output flag 35 is set. If this flag is not set, the operation is in the data reception mode as shown in the time period Tr in FIG.
The data signal D2r is received via the data signal D2r. After receiving the data, the polling signal transmission circuit 37 generates a polling signal P2, and sends it out from the output terminal 2-0 as shown in FIG. Here, the data signal D2r passes through the respective low-pass filters of the secondary stations 2 to 4 as shown in FIGS.
Returning to , the data is valid only for the secondary station 2 to which the polling signal P1 is applied. After sending the polling signal, the secondary station 2 returns to step 72 and repeats the same process.

In this way, by selecting an appropriate value for the data transmission timing t as shown in FIG.
2. P3. P4 is superimposed, making it possible to transmit data to each of the secondary stations 2 to 4.

Now, by the time the polling signal monitoring timer 12 times up, the polling signal receiving circuit 18 sends the last two
If the polling signal P4 is received from the next station 4, the process proceeds to step 46 via step 45, and the polling signal monitoring timer 12 is reset. If the polling signal monitoring timer times up within this period, the process proceeds to step 48 via step 47 without performing this process, and the polling signal monitoring timer 12 is operated again. Then, the process proceeds to step 49 to reset the data counter 23, and in step 50, the start signal S1 is sent from the start signal transmitting circuit 21 as shown in FIG. 6(a). As mentioned above, the start signal S1 is composed of an NRZ code with a frequency of 60 kHz like the data signal, so it passes through the low-pass filter of each secondary station 2 to 4 as it is and is transmitted to the primary station via the transmission line 5. Return to the input terminal 1-i of l.

Therefore, in step 51, the start signal receiving circuit 19
Check if a start signal has been received,
If the start signal is not received, there is a break in one of the transmission lines 5, so a break flag 37 is set (step 52).
If a start signal is detected, the process proceeds to START 53 without performing this process, and the polling signal detection circuit 18 gives a start signal to the polling signal transmitting circuit 11 to send out the polling signal P1. and step 54.5
At 5.56, the polling signal and 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 S
If 1 is detected, the output flag 35 is set (step 73
), enters data transmission mode and monitors the presence or absence of a polling signal. After that, if a polling signal is detected, the output flag 35 is set, so the process goes from step 75 to step 78, and the data D2s to be sent from the secondary station 2 to the primary station 1 is sent by the data signal transmission circuit 36. Since this data signal is composed of the same <60 KHz signal as the data sent from the primary station 1 to each secondary station, it is transmitted through the output terminal 1-o of the primary station 1 via the low-pass filter 31. The data is received by the data signal receiving circuit 20. Then, proceed to step 79 and output flag 3.
5 and returns to step 77 to send the polling signal P2 to the secondary station 3 in the same manner as in the reception mode described above. In this way, as shown in FIGS. 6(b), 6(c), and 6(d), data can be collected by the primary station by sequentially transmitting polling signals that provide transmission and reception rights to each secondary station. When the primary station 1 receives the data signal, it proceeds to steps 57 and 58 via step 55, increments the data counter 23, outputs the secondary station data of the counted value from the data reproducing circuit 22, and proceeds to step 54. return. When the polling signal P4 is given from the secondary station 4 in the last order, the data sending mode of the secondary station has ended, so the process returns from step 54 to step 41 and the same process is repeated thereafter.

However, the polling signal monitoring timer may time up without being given a polling signal. In this case, the process advances to step 59 via step 56, and it is checked whether the retransmission flag 13 is set. Since the retransmission flag 13 is initially reset, the process advances to step 60 to set the retransmission flag 13, and returns to step 49 to repeat the same process. If there is any abnormality, the polling signal monitoring timer 12 performs time amplification before the polling signal is detected again, so the process proceeds to step 61 via step 59, and it is checked whether the disconnection flag 14 is set. If the disconnection flag 14 is set, data has been sent normally up to the secondary station whose count value is indicated by the data counter 23, so data is transmitted between the secondary stations whose count value is (CN) and (CN+1). ′! s5
Since it can be determined that the wire is broken, the process advances to step 62 and the abnormality processing section 24 outputs the wire breakage. If the disconnection flag 14 is not set, it is determined that the secondary station (CN+1) following the count value (CN) is out of order (step 63), so the abnormality processing unit 24 outputs a message to that effect. The process ends.

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 after sending the start signal and polling signal, the primary station 1 sends the data from each secondary station. The polling signal generated by each secondary station by receiving the polling signal is superimposed between the two stations.
It becomes possible to send and receive data without setting an address for the next station.

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 start signal as they are and block only the polling signal, but it is also possible to use a low-frequency signal as the polling signal and modulate the data signal with a high frequency. It is also possible to change the filter that passes the data signal and start 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 the operation of the secondary station 2. The flowchart, Figure 6, shows each part of the transmission line of the multiplex transmission device a % d
FIG. 1...------・Primary station 2.3.4------
--・Secondary station 5-6. -・, transmission line 11.37
---Polling signal transmission circuit 12--Ro111 polling signal monitoring timer 16, 39--
Data signal transmission circuit 18, 33.--Polling signal detection circuit 19.---Start signal reception circuit 20.34.--Data signal reception circuit 21-.-. -Start signal transmission circuit 24
--・- Abnormality processing section 31 --- Low pass 2
Ilter 32-----Start signal detection circuit
35-1 Output Flag Patent Applicant Tateishi Electric Co., Ltd. Agent Patent Attorney Yoshiki Okamoto (and 1 other person) Figure 1 Figure 3 Figure 2 Start Signal Figure 5 Procedures Amendment (Spontaneous) June 1985 May 17, 1, Incident Display 1985 Patent Application No. 078941 2 Name of Invention Multiplex Transmission Device Address 10 Hanazono Tsuchido-cho, Ukyo-ku, Kyoto-shi, Kyoto Name (294) Tateishi Electric Co., Ltd. Representative Takao Miki 4. Agent address: 550 Yu, 3rd floor, Shinkoshisan Building, 1-13-38 Nishihonmachi, Nishi-ku, Osaka, Osaka Prefecture. Column 6: Detailed explanation of the invention in the specification to be amended. Contents of the amendment (1) r on page 9, line 17 and page 16, line 16 of the specification
The description of ``NRZ code'' will be corrected to ``bi-phase code.'' (2) Page 10, lines 18 to 19 of the specification. Page 12, line 6, page 16, line 16, and page 17, line 20
Change the description of r60KHzJ in the row to r60KHz and 30K
Correct it to Hz J. (3) The description of "rNRZ signal" on page 10, line 19 of the specification will be corrected to "pi-phase signal."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 transmission lines, and the primary station has transmission and reception rights when switching between data reception mode and data transmission mode. a polling signal transmitting means for transmitting a polling signal to the highest ranking secondary station; a data transmitting means for sequentially and intermittently transmitting data to each of the secondary stations after transmitting the polling signal; and from the data transmitting means. a start signal transmitting means for transmitting a start signal to set the secondary station in a data transmitting mode after transmitting the data; and after transmitting a start signal and a polling signal from the start signal transmitting means and polling signal transmitting means, respectively
and data receiving means for sequentially receiving data given from the next station, and each of the secondary stations is connected between input and output and passes the data signal and start signal obtained from the input terminal and blocks the polling signal. filter means; mode storage means for receiving a start signal and storing a data sending mode; data signal receiving means for receiving a data signal given after receiving a polling signal when in data receiving mode; and when in data sending mode. 1 after receiving a polling signal
The apparatus has a data sending means for sending data to the next station, and a polling signal sending means for sending a polling signal after the data receiving means receives the data signal and after the data sending means sends the data signal. A multiplex transmission device characterized by: (2) The polling signal sent by the polling signal sending means of the primary station and each of the secondary stations is a signal having a higher frequency than the data signal and the start signal, and the filter means of each of the secondary stations transmits the polling signal. 2. The multiplex transmission device according to claim 1, wherein the multiplex transmission device is a low-pass filter that blocks signals and passes data signals and start signals.