JPS6295045A - Multiplex transmission equipment - Google Patents

Abstract

PURPOSE:To automatically set an address, and to execute data transmission by constituting the titled device so that each secondary station holds an address signal after receiving a polling signal, and thereafter, the polling signal is sent out to the secondary station of the post-order, the address is set to each secondary station, and also setting of the address is ended, when the rolling signal has been applied to a primary station. CONSTITUTION:A polling signal transmitting circuit 27 is a transmitting circuit for sending out a polling signal to a secondary station 3 of the post-order, which has been connected to an output terminal 2-o of a secondary station 2, and thereafter, an operation start signal is applied to a comparator 26. The comparator 26 compares an address which has been received by an address signal receiving circuit 24, and an address which has been held in an address buffer 25, and when those address coincide, a signal by which transmission and reception can be executed is applied to a data signal transmitting/receiving circuit 22. The data signal transmitting/receiving circuit 22 executes a data transmission of the secondary station 2 and the primary station 1, transmits an output data which is given from the outside and outputs a received data, as an input data.

Description

[Detailed Description of the Invention] [Field of the Invention] The present invention connects a primary station (master station) and a plurality of secondary stations (slave stations) to two stations.
This invention relates to a multiplex transmission device configured by loop-connecting core wires in a digi-chain manner.

[4 Requirements of the Invention] The multiplex transmission device according to the present invention connects a large number of secondary stations to a primary station in a loop in a digital chain manner, and the primary station sequentially transmits signals to each secondary station in addition to a polling signal during initial operation. After receiving the polling signal, the secondary station holds the address signal and sequentially sends the polling signal to the subsequent secondary stations to set an address for all secondary stations, and from then on, the address is The data transmission is based on the following. With such a configuration, addresses can be automatically set for each secondary station, and the secondary stations can be easily installed.

[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 using a two-core dedicated line, the secondary stations are connected to any point on a common lotus. 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, if it is necessary to make the secondary station extremely compact, there is a problem in that the DIR switch restricts 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.

[Purpose of the invention]

The present invention has been made in view of the problems of conventional multiplex transmission equipment, and eliminates the need to set an address for each secondary station using a switch etc. at the time of installation, and automatically sets the address. An object of the present invention is to provide a multiplex transmission device that can perform data transmission.

[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 unique address signal to each secondary station intermittently in sequence. a polling signal transmitting means for transmitting a polling signal to the highest priority secondary station when setting an address; and a polling signal transmitting means for transmitting an address signal to each secondary station after transmitting the address signal to the secondary station. data transmission means, and each secondary station has a filter means connected between input and output terminals to pass the data signal and block the polling signal, and a polling signal given from the primary station or the upper secondary station. address signal holding means for holding the received address signal after receiving the signal; and polling signal sending means for sending the polling signal to the subsequent secondary station after receiving the polling signal from the primary station or the upper secondary station. , and data transmission means for transmitting data with the primary station after receiving the address for the secondary station.

According to the present invention having such characteristics, the primary station sends an address signal to the secondary station in the order of destination after sending the polling signal, and each secondary station holds the address signal after receiving the polling signal and uses it from then on. A polling signal is sent to the subsequent secondary station, an address is set for each secondary station, and address setting is completed when the polling signal is given to the primary station. Thereafter, after sending the address to each secondary station, normal data transmission is performed. With this configuration, there is no need to set the address for each secondary station using a DIP switch, etc. (it is possible to automatically set the address. Therefore, the secondary station can be made smaller and the secondary station This makes it possible to improve workability during installation.

[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 l and multiple 2
The next stations 2 to G are connected in a loop in a digital chain by a two-core transmission line 7. That is, the output terminal 1-0 of the primary station is connected to the input terminal 2-4 of the secondary station 2 connected to the highest order, and the output terminal 2-o of the secondary station 2 is connected to the next-order station by the transmission line 7. It is connected to the secondary station 30 input terminal 3-i. Similarly, the secondary station 3 connects to the secondary station 4 (not shown), and the secondary station 4 connects to the secondary station 2 (not shown).
The output terminal 5-0 of the secondary station 5 is connected to the input terminal 6-4 of the last secondary station 6, and the output terminal 6-o is connected to the input terminal 1 of the primary station 1. - connected to i. The primary station 1 sets an address for each secondary station B, and performs data transmission with the secondary station based on the address.

(Configuration of the primary station) As shown in FIG. 2, the primary station 1 has a polling signal transmitting circuit 11 that operates based on an external start signal and a counter 12 that is reset by the polling signal transmitting circuit 11. There is. When the polling signal transmitting circuit 11 is given a start signal, it transmits a polling signal modulated at, for example, a frequency IMIIz to the secondary station 2 connected first, and then the address signal receiving circuit 13
Give a start signal to The address signal transmitting circuit 13 transmits an address signal corresponding to the count value of the counter 12 to each secondary station 2 to 6. After transmitting the address signal, the address signal transmitting circuit 13 provides a count input to the counter 12, and at the same time, the data signal transmitting and receiving circuit 14 give an operating signal to the The data signal transmitting/receiving circuit 14 has input and output terminals connected to the input terminal 1-i and the output terminal 1-0, respectively, and receives data signals from each secondary station.
It sends a data signal to the next station, and also provides a count input to the counter 12 every time a data signal is transmitted or received.

The counter 12 amplifies and counts the counting input, and
The count value is applied to the address signal transmitting circuit 13, the comparator 15, and the count buffer 16.

Further, a polling signal receiving circuit 17 is connected to the input terminal 1-1 of the primary station 1. The polling signal receiving circuit 17 provides a seven-node signal to the count buffer 16, a reset signal to the counter 12, and a start signal to the address signal transmission counter 13. count buffer 16
holds the count value of the counter 12 when the set signal is applied, that is, the number of connected secondary stations, and provides the data to the comparator 15. If the count value of the counter 12 matches the number of secondary stations held, the comparator 15
It resets the counter 12 and provides a start signal to the address signal transmitting circuit 13.

(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 6 have similar configurations. Now, a low-pass filter 21 is connected to the input terminal 2-4 of the secondary station 2.
A data signal transmitting/receiving circuit 22, a polling signal receiving circuit 23, and an address signal receiving circuit 24 are connected.

The low-pass filter 21 is a passive filter made of LC, which blocks a signal with a frequency of IMHz used as a polling signal regardless of the power supply state, and which is transmitted from the transmission line 7 and modulated at a frequency below IMHz, for example, 60 KHz. It transmits address signals and data signals as they are to the output terminal 2-0. Address signal receiving circuit 2
4 transmits the address signal given from the input terminal 2-i to the address buffer 25 and comparator 26, and the polling signal receiving circuit 23 sets the address buffer 25 when receiving the polling signal, and further transmits the polling signal. The polling signal sending timing is given to the circuit 27. The polling signal transmitting circuit 27 is a transmitting circuit that transmits a polling signal to the subsequent secondary station 3 connected to the output terminal 2-0 of the secondary station 2, and thereafter gives an operation start signal to the comparator 26. The comparator 26 compares the address received by the address signal receiving circuit 24 with the address held in the address buffer 25, and if the addresses match, it sends a signal that enables transmission and reception to the data signal transmitting and receiving circuit. Give to 22. The data signal transmitting/receiving circuit 22 performs data transmission between the secondary station 2 and the primary station 1, transmits output data given from the outside, and outputs received data as manual data.

(Operation of this embodiment) Next, the operation of this embodiment will be described with reference to flowcharts and time charts. 4 and 5 are flowcharts showing the operations of the primary station 1 and each secondary station,
FIG. 6 is a time chart showing the signals of each part during the initial operation when setting an address. First, when the primary station 1 is given a start signal from the outside, it starts operating, the counter 12 is cleared, and the polling signal P1 is sent out from the polling signal transmission circuit 11 as shown in FIG. 6 (al) (step 31. 32). After sending the polling signal in steps 33 and 34, the counter 12 is incremented and the address signal A (11) is sent to the secondary station 2. The secondary station 2 waits for the polling signal in step 51 after starting operation. , if the polling signal P1 is received, the process proceeds to step 52, where the address signal A(1) is received from the address signal receiving circuit 24, and since the polling signal was received before that, the address buffer 25
Set to . Then, the process proceeds to step 53, where the polling signal transmission circuit 27 sends out a polling signal P2 to the secondary station 3 as shown in FIG. Check step 35). If no polling signal is received, the counter 12 is incremented and the address signal A(2) for the secondary station 3 is sent from the address signal transmitting circuit 13. After performing similar processing for secondary stations 3 to 5 and holding addresses A(2) to A(4) in their respective address buffers 25, secondary stations 4 to
Polling signal P3.6 for P3. P4. Send P5. The last secondary station 6 holds the address A(5) in its address buffer and then sends a polling signal P6 to the primary station 1 via the transmission line 7. Primary station l is step 3
When the polling signal P6 is received in step 5, step 3
Proceed to step 6 and transfer the count value of counter 12 to count buffer 1.
6 and completes the automatic address setting process.

Then, in order to start transmitting and receiving data to each secondary station (step 37), first proceed to steps 38 and 39 and count the counter 1.
2 and then increments counter 12. Then, the process proceeds to step 40, and as shown in FIG. 7 (al), the route address (K A
(il). This address signal is given to all secondary stations 2 to 6 via the low-pass filter 21 connected to the input and output terminals of each secondary station, and each secondary station 2 to 6 54. When an address signal is received at 55, it is checked whether the received address matches the held address.This address signal A (11 is 2
It matches only the address signal held in the address buffer 25 of the next station 2. Therefore, at secondary station 2, routine 5
The process advances to step 6 to transmit and receive data signals, and the other secondary stations then return to step 54 to wait for the next address signal. That is, as shown in FIGS. 7(al) and 7(b), the primary station 1 receives data from the secondary station 2 from the data signal transmitting/receiving circuit 14 in the routine 41.
When the data D and □ are sent, the secondary station 2 transmits the data signal D2 to the primary station 1. Thus 2
When the data transmission with the next station 2 is completed, the primary station 1 checks whether the count value of the counter 12 is equal to the number N of secondary stations held in the count buffer 16. If it is not equal to this value, the process returns to step 39, the counter 12 is incremented, and the address signal A (2
) is sent. On the other hand, when the data transmission in the routine 56 is completed, the secondary station 2 returns to step 54 and waits for the next address signal. Next, address signal A (2
) is sent out, data transmission is performed between the primary station 1 and the secondary station 3 as shown in FIG. 7(al, (C1). As shown in f), when the data transmission between the primary station 1 and each of the secondary stations 2 to 6 is completed, the count value of the counter 12 matches the count value of the count buffer 16. Therefore, the coincidence output of the comparator 15 The counter 12 is reset, and a start signal is again given to the address signal transmission counter 13.In this way, all
After completing one cycle of data transmission to the next station, data transmission and reception are repeated again to continue data transmission.

In this embodiment, a multiplex transmission apparatus using five 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. Further, in this embodiment, a low-pass filter is provided in each secondary station in order to pass the data signal as it is and cut off only the polling signal, but a band cutoff filter that cuts off only the frequency of the polling signal may be used. Furthermore, by using a low frequency signal as the polling signal and modulating the data signal at a higher frequency than the polling signal, it is also possible to construct the filter of each secondary station using a bypass filter that blocks only the polling signal.

Furthermore, in this embodiment, a multiplex transmission device that alternately transmits data between each secondary station and a primary station has been described. It goes without saying that the present invention can also be applied to.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing an embodiment of the multiplex transmission device according to the present invention, FIG. 2 is a block diagram showing the configuration of the primary station of the multiplex transmission device according to the present embodiment, and FIG. 3 is a block diagram showing the configuration of the secondary station. A block diagram showing the configuration of one embodiment, FIG. 4 is a flowchart showing the operation of the primary station, FIG. 5 is a flowchart showing the operation of each secondary station, and FIG. 6 is a flowchart showing the operation of each secondary station.
The first time to set the address for the next station! IJJ vJ
Figure 7 is a time chart showing the data transmission status of each station during normal data transmission operation.1-1~----Primary station 2~6-m----2
Next station 7----Transmission line 11, 27---
-Polling signal transmission circuit 12--1--counter
13---Address signal transmission circuit 14, 2
2---Data signal transmission/reception circuit 15, 26---
-- Comparator 21 --- Low-pass filter 24
---Address signal receiving circuit 25-----1111 Address buffer Patent applicant Tateishi Electric Co., Ltd. Agent Patent attorney Kanki Okamoto (and one other person) Figure 1 Figure 2 Figure 2 "-'771"u Figure 3 Figure 4

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 sequentially transmits a unique address signal to each of the secondary stations. address signal sending means that sends out intermittently, polling signal sending means that sends a polling signal to the highest priority secondary station when setting an address, and data exchange with the secondary station after sending the address signal to each secondary station. data transmission means for transmitting data, and each of the secondary stations has: a filter means connected between input and output terminals for passing data signals and blocking polling signals; Address signal holding means for holding an address signal received after receiving a polling signal given from a station; and sending a polling signal to a subsequent secondary station after receiving a polling signal from a primary station or an upper secondary station. A multiplex transmission device comprising: polling signal sending means; and data transmission means for transmitting data with a primary station after receiving an address for the secondary 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 signal and address signal,
2. The multiplex transmission apparatus according to claim 1, wherein the filter means of each of the secondary stations is a low-pass filter that blocks the polling signal and passes the data signal and address signal.