JPS61123234A - Terminal device exclusive for reception - Google Patents

Abstract

PURPOSE:To monitor freely an optional device by connecting the titled device to a ring transmission network, designating kinds of an address and the data of a terminal device to be received and transmitting a reception data at every time when the designated data is received. CONSTITUTION:A reception signal from a reception terminal 1 is subject to a level conversion 3 and when a start bit is detected 6, a synchronization clock is generated 7, the reception signal is sampled 8 to output it to a reception bypass signal line 16. A reception data selection circuit 13, according to the content of a transmission/reception switch signal line 18, applies a level conversion 4 to the signal of the bypass line 16 at reception and to a transmission signal 17 at a transmission and transmits 2 the result. According to the command of a microcomputer 19, the address of a terminal device to be received is designated, the kind of the data to be received is designated and when the designated address and data are received, the said designated data is retransmitted through the reception bypass line 16 on each occassion. Thus, the terminal device acts as a reception-only device and the center device monitors an optional terminal device.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention provides a monitor output function for input/output status in a data transmission system that transmits input/output data or a system that transmits data between data transmission units. The present invention relates to a receiver dedicated terminal device having a receiver.

[Prior art and its problems]

The reception-only terminal device in this data transmission system is conventionally used in a system in which a center device 24 and a plurality of terminal devices 25 are connected on a transmission path as shown in FIG. The transmission method (arrow a) in which the receiving terminal receives the output transmission data of the transmitting terminal from the transmission path 26 and outputs the received data to the output terminal of the receiving terminal, and the receiving terminal is specified from the center device 24. However, a transmission method (arrow b) is known in which a designated terminal device receives output data transmitted from a center device and outputs the received data to an output terminal.

However, in the case of the above-mentioned receiving terminal, since it is preset as a receiving terminal on the transmission system and also has a function to notify the other party that reception has been completed, it is possible to change the communication partner, that is, to use a different address terminal. There is a problem in that if you want to receive data for a different address from a device or a center device, it cannot be easily changed. This is because when the address is set as a receiving terminal, the sending terminal or center equipment receives a reception confirmation signal from the receiving terminal and determines that the communication was successful, so if the receiving terminal address is changed, this confirmation signal is received. This is because a communication error will occur because this is not possible. It is also possible to use +aft receiving terminals with the same address. In this case, multiple terminals send out reception confirmation signals at the same time or with a slight time difference, so they can be sent once on a common transmission line. Since two or more types of signals are output, there is also the problem that data may collide, making normal data transmission impossible. In addition, in a system that transmits data between the data transmission units (terminals) 27 and 28 in Figure 2, another receiving terminal is connected between the terminals of the other party, and the transmission output of one or the other party's terminal is It is conceivable that the same content as the data is received and output at another location, but in this case as well, one or more terminal devices participate in the data transmission that normally takes place between two terminal devices, so communication still continues. There is a problem that data cannot be transmitted due to a collision of confirmation data.

[Purpose of the invention]

This invention enables connection to a data transmission line without restrictions on the specified address range in a data transmission system in which a center device and a plurality of terminal devices are connected, or in a system in which data is transmitted between terminal devices. It is an object of the present invention to provide a reception-only terminal device that can freely select and receive data that is being transmitted by a center device or a terminal device without affecting the transmission data that is being sent or received.

[Key points of the invention]

The key point of this invention is that it is connected to a transmission line of a data transmission system that connects a center device and a plurality of terminal devices, or a system that transmits data between terminal devices, and is capable of selectively receiving the data of the main transmission line. 42 means for setting the address of the terminal to be received, 42 means for specifying the type of data to be received, and each time the data specified by the first means and the second means is received. and a third means for outputting the received data.

[Embodiments of the invention]

FIG. 1 shows a schematic configuration diagram of a reception-only terminal according to the present invention. In Fig. 1, 1 is a receiving terminal, 2 is a transmitting terminal, 3.4 is a level converter, 5 is a receiving signal line, 6 is a start bit detector, 7 is a synchronous clock generator, 8 is a sampling circuit, and 9° 10 is an AND circuit, 11 is an OR circuit, 12 is an inverter circuit, 13 is a transmission data selection circuit, 14 is a start bit detection signal line, 15 is a synchronous clock signal line, 16 is a reception bypass signal line, 17 is a transmission signal line, 1B is a transmission/reception switching signal line, 19 is a microcomputer (hereinafter referred to as microcomputer), 21 is an output level conversion circuit, 22 is an output terminal, and 23 is a setting key matrix.

In such a configuration, the operation of the reception-only terminal is as follows.

L/ /< /L/Converter 3 is l(, S-232C, 2
A 0 mA current loop converts an optical signal into a signal at a voltage level used within the device (for example, TTL level). The converted received signal activates the synchronous clock generator 7 when the start bit is detected by the start bit detector 6.

The sampling circuit 8 samples the pressure level of the received signal line 15 (7) at the rising edge of the synchronous clock waveform from the synchronous clock generator 7, and obtains the same level (for example, TTL).
level) is output to the reception bypass signal line 16. The transmission 4g data selection circuit 13 transmits the signal on the bypass signal line 16 during reception and the signal on the transmission signal line 17 during transmission to the level converter 4 according to the contents of the transmission/reception switching signal line 18. The level converter 4 converts the voltage level /L/ (TTL L/ to /L/) used within the device again into an R, S-232C, 20 mA current loop-1 optical signal, etc., and transmits it to the next device.

The microcomputer 19 has a function of performing serial transmission, and when receiving a serial signal, it sets the transmission/reception switching signal line 18 to "H" level, and also sets the synchronous clock signal line 15 generated by the start bit of the received data.
Serial data can be read by sampling the level of the received signal line 5 at the rising edge of the synchronous clock. Furthermore, when transmitting a serial signal, the transmission/reception switching signal line 18 is set to 'L' level, and the serial superstition data can be outputted from the transmission signal line 17. With this configuration, the received signal converted by the level converter 3 is sampled. It can be bypassed via the circuit 8 and retransmitted onto the transmission line by the level converter 4. At this time, the transmission/reception switching signal on the line 18 is selected on the receiving side. The reason for this is that a device is manufactured with the same circuit configuration as the transmitting/receiving terminal, and a part of it is used to create a receiving-only terminal.

Figure 2 shows the character structure of the asynchronous serial transmission data flowing on the reception signal line 5, and the data bits are bd
, ~bd, 8 bits, 2 stop bits. In this case, the start bit must be 1L''
The stop bit is set to "H", and the state between characters, that is, from the stop bit to the next character start bit, is "H" (mark state).When such one character is received, Microcomputer 1
9, the microcontroller 19 inputs the serial data as parallel data, and when it receives the specified number of characters in the transmission, it checks the data for errors and determines that the data is correct by checking the terminal address information contained in the data. and the address shown in the setting key matrix 23, and if the addresses match, the terminal data following the address information of the received data is transferred to the output level conversion circuit 21.
The data is output to the data output terminal 22 via. If the addresses do not match, the received data is discarded. With the above transmission data control, the reception-only terminal device is always in the data reception mode, and continues to output the previously received data to the data output terminal until data is received by the set address terminal device. In addition, in the case of a general terminal, when it receives data corresponding to its own terminal on the transmission line, it sends out a reception OK double signal in the case of normal reception and a reception NG signal together with its own address in the case of abnormal reception at the subsequent transmission communication interval. and sends a confirmation signal to the data source. Therefore, in general terminals, if the address is not changed at the time of system design or system change, there is a risk that a communication error will occur.

In the data transmission system shown in FIG.
When data is transmitted between the terminal device 25 and the center device 24
There are two types of communication: data output (Do) communication that transmits data held by the terminal to the terminal and outputs the data to the output terminal of the terminal, and data input (Dl) communication that transmits the status of the input terminal of the terminal to the center device 24. . In this case, since two types of data are sent and received with a terminal device with one address, does the reception-only terminal monitor this data output data?
It is necessary to specify whether data input data is to be monitored. For this reason, in a reception-only terminal device, a switch for selecting data selection is provided in the setting key matrix 23, so that two types of data can be selectively displayed.

In a reception-only terminal used in a data transmission system configured with a center device in this way, a selection switch is provided to specify the address to be received and the type of data to be received, and when a reception-only function is specified, By excluding the reception confirmation function and not updating the reception output only when the monitored data matches the address to be received, it can be used as a reception-only terminal with the exact same configuration as a normal reception terminal. can do.

In a receiving-only terminal in a system that transmits data between data transmission units (terminals) shown in Figure 4, the configuration of the terminal is as shown in Figure 1, regardless of whether it is a general receiving-only terminal. Therefore, one terminal is used as a mask terminal to take the lead in transmission, and the other is used as a slave terminal to perform transmission between the mask or slave terminals. In this configuration, the transmitted terminal data is in a transmission loop configuration that returns to the receiving terminal of the own terminal, so it is not possible to distinguish between the master and slave output data by simply connecting a reception-only terminal on one transmission line between them. You will receive it without having to do so. In addition, the transmission output data contents of the mask and slave are each attached with data including a code indicating whether the data is transmitted from the mask side or the data transmitted from the slave side, and error check data. A setting switch is provided to select whether to receive data from either the mask or slave side, making it possible to monitor output.

〔Effect of the invention〕

According to this invention, in a general-purpose data transmission system in which a central office and a plurality of terminals are connected in a loop, a reception-only terminal can be connected, so data from the same terminal can be monitored by multiple terminals. Since this reception-only terminal can be changed to any address, it is possible to monitor the deafness of any terminal. In addition, when transmitting data between terminal devices, even if a receiving-only terminal is connected to either bidirectional transmission line, it is possible to freely select whether to monitor the contents of mask or slap by changing the switch settings. It is. The reception-only terminal is one of the general terminals.
Since it is a built-in function, there is no need to connect special equipment for monitoring.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a reception-only terminal according to the present invention, FIG. 2 is a character configuration diagram of asynchronous serial transmission data,
FIG. 3 shows a configuration diagram of a loop transmission system, and FIG. 4 shows a configuration diagram of a two-way transmission system. DESCRIPTION OF SYMBOLS 1... Reception terminal, 2... Transmission terminal, 3.4... Level converter, 5... Reception signal line, 6... Start bit detector, 7... Synchronous clock generator, 8...
・Sampling circuit, 9, 10...AND circuit, 11
... OR circuit, 12 ... Inverter circuit, 13 ...
・To transmission data selection time 14... Start bit detection signal line, 15... Synchronous clock signal line, 16.
...Receiving bypass signal line, 17... Transmitting signal line, 18... Transmitting/receiving switching signal line, 19... Microcomputer, 21... Output level conversion circuit, 2
2...Output terminal, 23...Setting key matrix. 10 years old 2Z E)0 data pλ data 'f'4 diagram

Claims (1)

[Claims] 1) A device that is connected to a transmission line of a data transmission system that connects a center device and a plurality of terminal devices, or a system that transmits data between terminal devices, and can selectively receive data on the transmission line, a first means for setting the address of the terminal to be received; a second means for specifying the type of data to be received; A reception-only terminal device comprising at least a third means for outputting an output.