JPS61237547A - Multiplex transmission equipment - Google Patents

Abstract

PURPOSE:To continue the signal transmission even when a trouble happened to the line connection a primary station and plural number of a secondary station in loop, by changing the primary station to loop back mode and turning back the signal from the adjacent station to the trouble. CONSTITUTION:Plural number of secondary stations 2-5 are connected in loop to a primary station 1 by two-core transmission cable 6. The primary station 1 outputs poling signal, start signal and data signal from its output terminal 1-0. The secondary station takes in the poling signal and when own station is specified, receives the data by the start signal from the higher rank station and sends out data of own station to lower station. When own station is not specified, it delivers the data to the lower station. When no start signal nor data signal is received at input terminal 1-i, the primary station 1 is changed to loop back mode, and sends out signals from both input and output terminals, and receives by both terminals the signal returned back from the adjacent station to the trouble. In this way, the multiples transmission can be continued even when there occurs a trouble.

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 loop in a digital chain manner using dedicated two-core wires. The present invention relates to a multiplex transmission device, and particularly to a multiplex transmission device that can detect a break in a transmission line or an abnormality in a secondary station and continue data transmission even in the event of an abnormality.

[Summary of the invention]

In the multiplex transmission device according to the present invention, a primary station transmits a start signal at the beginning of each step, transmits a polling signal which is a transmission/reception right to a secondary station in the highest order, and sequentially receives data signals from the secondary station. and a plurality of 2 stations connected in a continuous loop to the primary station in a digital chain manner to receive polling signals from the preceding station, transmit data to the primary station, and send polling signals to subsequent stations. A second station was established.

The primary station has a switching circuit that switches the abnormal input/output terminal, and two
By providing an address counter that detects the address of the next station, an abnormal state of the secondary station can be recognized, and input/output terminals are switched in the event of an abnormality. 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 making the secondary station extremely compact, there is a problem in that the DrP 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, data transmission cannot continue, and it is difficult to easily detect such an abnormality. there were.

[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 the next station, can easily detect a disconnection of a transmission cable or an abnormality in a secondary station, and can continue data transmission even in the event of an abnormality. shall be.

[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 has transmission and reception rights to the secondary station connected to the primary station. a polling signal sending means for sending out a polling signal, and a break in the transmission line for detecting a break in the transmission line by sending a start signal from one end of the primary station and receiving the start signal from the other end;
a detection means, a data reception means for receiving a data signal from a secondary station, and a switching means for detecting reception of a data signal within a predetermined time and switching input/output terminals of the primary station when no data signal is obtained. , a data counter that is sequentially incremented as data is received in each operation cycle, and an abnormality processing unit that detects an abnormal state based on the detection of the data counter and the disconnection detection means. is connected between the input and output terminals and passes the data signal and start signal obtained from either terminal and blocks the polling signal, and the polling signal receives the polling signal obtained from either of the input and output terminals. a receiving means, a data polling signal transmitting means for transmitting a data signal and a polling signal to the primary station when the polling signal receiving means receives the signal, and a polling signal operated by the received output of the polling signal receiving means and given to the secondary station. and switching means for sending the polling signal and the data signal to different terminals.

According to the present invention having such characteristics, a start signal, a polling signal, and a data signal are transmitted using a two-core transmission line, and each secondary station receives a polling signal, which is a transmission/reception tower, and then transmits a start signal, a polling signal, and a data signal. Data is transmitted to the station, and then polling signals are sequentially transmitted to secondary stations in the subsequent order. If the start signal or data signal is not transmitted to the primary station, the abnormality processing circuit determines the abnormality, and the input/output switching circuit of the primary station switches the input/output terminals of the primary station. Therefore, it is possible to automatically detect an abnormality in the secondary station or a disconnection state in the transmission line, and even in the event of such an abnormality, it is possible to continue data transmission except for the part that has become abnormal. Furthermore, since addresses are not set for each secondary station, there is no need to provide a DTP 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 2.3.4 are loop-connected in a digital chain by a two-core transmission line 5.

In other words, the output terminal 1-o of the primary station is the terminal 2 connected to the highest order.
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 secondary station 4, and the output terminal 4-o is connected to the input terminal 5-i of the last secondary station 5. Its output terminal 5-o is connected to the input terminal 1-i of the primary station 1 via a transmission line 6. The primary station 1 sends out a start signal for each operation cycle, and thereafter sends a polling signal to the secondary station with the highest priority as a transmission/reception right, and sequentially receives data signals from each secondary station. It also detects an abnormality in the transmission A6 and continues data transmission.

(Configuration of Primary Station) As shown in FIG. 2, the primary station 1 includes a start signal transmitting circuit 11 that operates based on an external start signal. Data signal monitoring timer 12, polling signal monitoring timer 13, and retransmission flag 14 that is reset by the start signal. Disconnection flag 15. loopback flag 16
and a secondary station ranking determining section 17. The start signal transmitting circuit 11 sends out a start signal from the primary station 1 at the beginning of each operation cycle to detect a disconnection state of the transmission line 6.
A start signal modulated with a Hz signal is sent out.

The sending timing is determined by the polling signal transmitting circuit 1.
given to 8. The polling signal transmitting circuit 18 is a circuit that transmits a polling signal having a frequency of, for example, IMHz, and these transmitting circuits 11 and 18 are supplied with the output of an oscillator 19 that determines a transmission clock. A gate circuit 20.21 driven by a loopback flag 16 is provided at the input/output terminals 1-i and 1-o of the primary station 1.

When the loopback flag 16 is reset, the gate circuit 2
0.21 is the normal mode shown in Figure 2,
At this time, the start signal transmitting circuit 11 is connected to the output terminal 1-o.
．． Polling signal transmitting circuit 18 and data signal receiving circuit 2
2 is connected. The data signal receiving circuit 22 is a circuit that receives data from each secondary station, and provides the data output to the data signal reproducing circuit 23 and outputs it to the outside.
The data reception timing is given to the data signal monitoring timer 12. The data signal monitoring timer 12 transmits an abnormality signal to the abnormality processing section 24 when a data signal is not obtained within the time when the data signal should be received. Further, the reproduction output of the data signal reproduction circuit 23 is transmitted to the data counter 25. The data counter 25 is incremented each time data is received, and its count output is transmitted to the abnormality processing section 24 and the secondary station ranking determination section 17 and used for detecting an abnormal location. In the normal mode, a start signal detection circuit 26 and a polling signal detection circuit 27 are connected to the input terminal 1-i via the gate circuit 21.

The start signal detection circuit 26 is the start signal transmission circuit 11
The signal sending timing is given by
A disconnection state of the transmission line 6 is detected based on whether or not a signal is received, and if a start signal is not detected, a disconnection flag 15 is set.

The polling signal detection circuit 27 detects the polling signal from the secondary station, and its output is transmitted to the outside as a one-scanning completion signal, and resets the timer and each flag in the same way as the start signal. Also retransmission flag 1
A flag 4 is set when restarting the operation when an abnormality is detected, and is used together with the abnormality processing section 24 to detect an abnormality and disconnection state of the secondary station.

(Configuration of Secondary Station) FIG. 3 is a block diagram showing the configuration of the secondary station 2, and the other secondary stations 3 to 5 have similar configurations. Now, a low-pass filter 31, a polling signal detection circuit 32, and a gate circuit 33 are connected to the input/output terminals 2-i and 2-0 of the secondary station 2. The low pass filter 31 is LC
It is a passive filter that blocks the IMHz frequency signal used as a polling signal given from one terminal regardless of the state of the power supply, and blocks the IMHz frequency signal given from the transmission wA6 or below, for example 60 KH.
This is a filter that transmits the data signal and start signal modulated by z to the other terminal as they are. Further, the polling signal detection circuit 32 receives the polling signal applied via the transmission line 6 and provides the data signal transmission circuit 34 with the timing for transmitting the data signal, and also provides the gate circuit 33 with a control signal. The gate circuit 33 controls the data signal to be sent from the terminal opposite to the input/output terminal where the polling signal is detected. The data signal transmitting circuit 34 transmits data output onto the transmission line 6 via the gate circuit 33, and inhibits the operation of the polling signal during this time. The oscillator 35 provides a reception clock to the data signal transmission circuit 34.

(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. Figures 5, 6゜7 (a) - (11
! 1 is a waveform diagram showing signal waveforms at each point of a x e shown in FIG. 1, FIG. 5 shows waveforms in normal times, and FIGS. 6 and 7 show waveforms in abnormal times. In these figures, when the primary station 1 is given a start signal, it starts operating, and first proceeds to step 41 in FIG. 4, where the retransmission flag 14. Disconnection flag 1
5 and the loopback flag 16 are reset. By resetting the loopback flag 16, the gate circuit 20.
21 is the normal mode shown in FIG. Then, in step 42, the data signal monitoring timer 12. The polling signal monitoring timer 13 starts operating, and the process advances to step 43 to reset the data counter 25. Then, in step 44, the start signal transmission circuit 11 sends out the start signal S1 onto the transmission line 6 as shown in FIG. 5(a). For example, since the start signal Sl is modulated with a signal with a frequency of 60 KHz as described above, it passes through the low-pass filter of the secondary station as it is and is input to the input terminal 1- of the primary station I.
given to i. Therefore, if the start signal is not detected by the start signal detection circuit 26, the process proceeds to step 46 and the disconnection flag 15 is set; if the start signal is detected, the process proceeds to step 47 without performing this process and the process shown in FIG. 5(a) is performed. As shown, the polling signal transmitting circuit 18 sends out a polling signal P1. The process then proceeds to step 48 to check whether the polling signal detection circuit 27 detects a polling signal.

Now, the secondary station 2 detects the polling signal P1 given from the input terminal 2-i by the polling signal detection circuit 32, and sends the detection signal to the data polling signal transmission circuit 34, which causes the gate circuit 33 to operate as shown in FIG. Change the connection to the polling signal detection terminal and reverse direction. Then, the data polling signal transmitting circuit 34 is transferred to the gate circuit 33.
The data signal D2 is outputted via the output terminal 2-o as shown in FIG.
The polling signal P2 is sent out as shown in FIG. The primary station 1 is waiting for polling signals and data signals in steps 48, 49 and 55, and when the data signal D2 is received, the process proceeds from step 49 to step 50.51, resets the data signal monitoring timer 12, and receives the data signal. The counter 25 is incremented. Then, in step 52, it is checked whether the loop bank flag 16 is set, and if this flag is not set, then in step 53, the data output from the secondary station of the count value (CN) of the data counter 25 is determined. as data signal regeneration circuit 2
At the same time, the secondary station ranking determination unit 17 outputs the ranking output at the same time.

Then, the process returns to step 48 to wait for a data signal and repeat the same process. The secondary station 3 similarly connects the input terminal 3-
If the polling signal P2 is given from C1 in FIG.
As shown in , the data signal D3. The polling signal P3 is sent out in sequence, and in response, the primary station 1 receives data, outputs the data output and the ranking output to the outside, and finishes receiving the data D2 to D5 from each secondary station. When the polling signal P5 is sent from the last secondary station 5, it is detected by the polling signal detection circuit 27 of the primary station 1, and the detection signal is transmitted to the outside as a one-scan completion symbol, and the process returns to step 41 to each The flag is reset, the timer is activated, and the same process is repeated.

(Operation during abnormality) Next, the operation when the secondary station is out of order will be explained with reference to waveform diagrams. If the secondary stations 2 and 3 are operating normally, then after time t1, as shown in FIGS. 6(a) and 6(b).

As shown in (C), data signals and polling signals are sequentially transmitted from the secondary station 2.3. After that, the polling signal P3 is transmitted to the secondary station 4, but if the secondary station 4 fails and does not send out the data signal, step 48.49.55
loop is repeated. When the data signal monitoring timer 12 having the timer time T2 times out, the process proceeds to step 56 and the retransmission flag 14 is checked. If the retransmission flag 14 is not set, the process advances to step 57 and the polling signal monitoring timer 1 having the timer time T1 is activated.
Check whether 3 times up. As shown in FIG. 6(C), when this timer times up at time t2, the retransmission flag 14 is set, and the process returns to step 43 to repeat the same process. Then, the data counter 25 is reset, the start signal S1 and the polling signal P1 are sent out, and the same operation is repeated thereafter. At this time, the timer 12 is reset after receiving the data signal D3 (step 50), but since no data signal is obtained from the secondary station 4, the data signal monitoring timer 12 time-amplifies from step 55 to step 56 at time t3. The process then proceeds to step 59, where it is checked whether the loop bank flag 16 is set. If this flag is not set, proceed to step 60 and check the disconnection flag 15, and if the disconnection flag is not set, proceed to step 61, which is the address 2 of the count value CN+1 of the data counter 25.
It is determined that the next station, that is, the secondary station 4 is out of order. If this flag is set, it is determined that the transmission line between CN and CN+1, in this case the transmission line between secondary stations 3 and 4, is disconnected. The process then proceeds to step 63, sets the loopback flag 16, and returns to step 43. By setting the loopback flag 16, the gate circuit 20.21 is switched to the loopback mode shown in broken lines in FIG. Then, the process returns to step 43 to reset the data counter 25, and the start signal is output to the gate circuit 2.
1 from the input terminal 1-i. If the start signal S1 is not detected from the output terminal 1-o, the disconnection flag 15 is set and the same process is repeated. In this case, as shown in FIG. The signal is applied from the output terminal 5-o of the station 5, and the secondary station 5 sequentially sends out the data signal D5 and the polling signal P5 from the input terminal 5-i as shown in FIG. 6(d).

If the primary station 1 receives the data D5, it performs steps 50 and 51.
, the data signal monitoring timer 12 is reset and the data counter 25 is incremented, but since the loopback flag 16 is set, the process proceeds to step 54 and the secondary station data of the secondary station number N-CN+1 is transferred to the data signal regeneration circuit 2.
The third and second station ranking determination unit 17 outputs it to the outside. Now, the polling signal P5 is transmitted to the secondary station 4, but in this case as well, if the secondary station 4 is out of order, the process advances to step 64 via step 59, and the state of the disconnection flag 15 is checked. If 15 is not set, the number of secondary stations is N-
If the secondary station of CN is out of order and the disconnection flag 15 is set, a disconnection in the section from N-CN to N-CN+1 is detected (steps 65 and 66). Then, proceed to step 67, reset the loop bank flag 16, and step 43
Return to

Next, as shown in FIG. 7, from time t4, the start signal S1
However, if the transmission line 6 between the secondary stations 4 and 5 is disconnected at time t5 while the secondary station 3 is transmitting the data D3, the data signal D5 is sent to the primary station. 1
The loop of steps 48, 49, and 55 is repeated to check whether or not the polling signal monitoring timer 13 time-amples based on the time-up of the data signal monitoring timer 12 as described above. Then, at time t6 when this timer times up, the retransmission flag 14 is set and the start signal is sent again from step 44, but at this time, the start signal is not transmitted to the primary station, so the disconnection flag 15 is set at step 46. A disconnection condition is confirmed. After this, FIG. 7(b).

(C1, (dl), the data D2, D3, and D4 are transmitted from the secondary stations 2, 3, and 4 to the primary station, respectively. Thereafter, in step 55, the data signal monitoring timer 12 times out, so that the data signal monitoring timer 12 times out in step 59. .In step 62, the disconnection section is detected by the abnormality processing unit 24, and the loopback flag 16 is set.Therefore, from time t8, the loopback mode is entered, and as shown in FIG. Then, the data D5 is transmitted from the secondary station 5 to the primary station 1 as shown in FIG. All 2 regardless of transmission line breakage.
Data transmission with the next station can be continued.

In this way, primary station 1 can sequentially receive data from each secondary station after sending out a polling signal, and 2
Abnormalities and disconnections at the next station can be automatically detected. Furthermore, in the event of a disconnection, by using the loopback mode, it is possible to perform data transmission with all secondary stations regardless of the disconnection.

In this embodiment, a multiplex transmission apparatus using four 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 to 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
6 and 7 are waveform diagrams showing the waveform of the transmission line a%e of the multiplex transmission device when an abnormal state occurs. 1. -Primary station 2, 3, 4.5---
---Secondary station 6---Transmission line 11--Start signal transmission circuit 12--Data signal monitoring timer 13-Low--Polling signal monitoring timer
14--------One retransmission flag 15-----One disconnection flag 16-----Loop back flag 1
8--Polling signal transmission circuit 20, 21
．． 33--------Gate circuit 22-- Data signal receiving circuit 24------ Abnormality processing section
26--Start signal detection circuit 27----
--Polling signal detection circuit 31--Low pass filter 32--Polling signal detection circuit
34...--1--Theta polling signal transmission circuit patent applicant Tateishi Electric Co., Ltd. agent Patent attorney Yoshiki Okamoto (and one other person) Procedural amendment written (voluntarily) June 17, 1985 1 , Indication of the case 1985 Patent Application No. 078944 2 Name of the 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: Shinkosan Building 3rd Floor 5, 1-13-38 Nishihonmachi, Nishi-ku, Osaka-shi, Osaka 550, Detailed explanation of the invention in the specification to be amended, Column 6, Contents of the amendment (1) Page 10 of the specification The description of ``rNRZ code'' in the first line will be corrected to ``biphase code.'' (2) The description of r60KHzJ on line 10 of the specification, line 14 of page 12, and line 7 of page 14 will be corrected to r60KHz and 30KbJ. 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 and receives data to and from the secondary station connected to the primary station. a polling signal sending means for sending out a polling signal that is a polling signal; and a disconnection detecting means for detecting a break in the transmission line by sending a start signal from one end of the primary station and receiving the start signal from the other end; data receiving means for receiving a data signal from the next station; switching means for detecting reception of a data signal within a predetermined time and switching input/output terminals of the primary station when no data signal is obtained; and for each operation cycle. a data counter that is sequentially incremented as data is received; and an abnormality processing unit that detects an abnormal state based on the data counter and the detection of the disconnection detection means, and each of the secondary stations has input/output. filter means that is connected between the terminals and passes the data signal and start signal obtained from either terminal and blocks the polling signal; and polling signal receiving means that receives the polling signal obtained from either the input and output terminals; data polling signal transmitting means for transmitting a data signal and a polling signal to the primary station when a signal is received by the polling signal receiving means;
A multiplex transmission device comprising: switching means for transmitting the polling signal and the data signal to a different terminal than the polling signal given to the next station. (2) The polling signal sent out 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 and start signals, and
2. The multiplex transmission apparatus according to claim 1, wherein the filter means of the next station is a low-pass filter that blocks the polling signal and passes the data and start signal.