JPS63236438A - Modem - Google Patents

Abstract

PURPOSE:To constitute a system so as not to generate system down even when a loop is formed by connecting a device which judges the reception of the data of its own station as line abnormality, by providing a switching means, and separating a reception part from a transmission line when the data is sent from its own station. CONSTITUTION:At a time when an RS signal 23 is set at an ON state (level H), a switch 53 is closed, and transmission data is sent from a transmission part 22 to the transmission line 26 via a transformer T2. At this time, the signal 23 is inverted by an inverter 24, and is added on switches S1 and S2, and the switches S1 and S2 are opened, and the data transmitted from its own station is not received by the reception part 21 even when the data is returned from the transmission line 26 by loop connection, and is not sent to the transmission line 26. Adversely, at the time when the signal 23 is set at an OFF state (level L), the switch S3 is opened, and also, the switches S1 and S2 are closed, and the data sent from another station is inputted to the reception part 21 from the transmission line 25 via a transformer T1, and also, it is sent to the transmission line 26 via the transformer T2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a modem used for data transmission through a loop connection.

(Prior Art) An example of connection when modems are connected in a loop and used for a polling system is shown in FIG. (hereinafter referred to as DTE), and 7 to 12 indicate modems (hereinafter referred to as modems). CPLll and modem 7, DT
E2 and modem 8, DTE3 and modem 9, DTE4 and modem 10. DTE5 and modem 11, DTE6 and modem 1
2 are connected by terminal interfaces (not shown), respectively, and are the transmission output terminals (S) of modems 7 to 12 of modems 7 to 12.
The reception input terminals (R) are connected in a loop through transmission paths 13-18.

Regarding the control of the transmission output and reception input inside the modem conventionally used for such loop connections, the fourth
Referring to the figure, the modem 8 connected to the DTE 2 will be explained as an example.

DTE2 receives polling from CPU1 and CPLI
When returning a response to I, inside the modem 8, the fourth
As shown in FIG. 2A, received data 19 arriving from the F transmission line 18 is input to the delusion unit 21, and transmitted data 20 is outputted to the transmission line 13 by the transmitting unit 22.

On the other hand, in the case below, that is, when the DTE 2 does not return a response to the CPU 1, the received data 19 arriving from the transmission path 18 is input to the receiving section 21 as shown in FIG. It is output to the transmission line 13. modem 7,
The same applies to 9.10.11.12. Now, DT
When E2 returns a response to the polling from CPU1, the modem 8 is shown in FIG. 4(a), the modem 7 below it,
9.10.11 performs the operation shown in FIG. 4(b). At this time, the data sent from the transmitting section 22 of the modem 8 to the transmission line 13 is input to the receiving section of the modem 9, and the data is sent to the transmission line 13.
Sent on 4th.

Similarly, the data transmitted by the transmitter 22 of the modem 8 via the modem 10.11.12.7 and the transmission line 15.16.17.18 between them is sent from the transmission line 18 to the modem 8.
The received signal arrives at the receiving section 21 of.

By the way, some DTEs, when receiving data sent from their own station, determine this as a line abnormality and stop the system. If a loop-connected polling system is configured by combining the TE and the conventional modem described above, the DTE will stop the system. For this reason, this modem could not be used in such systems.

(Problems to be Solved by the Invention) As described above, when conventional modems are connected in a loop, they receive data sent from their own station. For this reason,
When a polling system is configured using a loop connection by combining this conventional modem and a DTE that determines that there is a line abnormality when it receives data sent from its own station, there is a problem in that the system stops.

The present invention was made to eliminate this problem, and its purpose is to configure a polling system using a loop connection by using it in combination with a DTE that determines that there is a line abnormality when receiving data sent from its own station. The purpose of the present invention is to provide a modem that will not cause a system down even if

[Structure of the Invention] (Means for Solving Problems) The present invention has a receiving section and a transmitting section, is connected to a receiving side transmission line and a transmitting side transmission line, and is connected to these transmission lines and data belonging to the local station. In a modem device that is located between a processing device and modulates and demodulates a signal, when the data processing device sends data to the transmitting side transmission path, the receiving side transmission path and the receiving section of the own device are separated, and , while connecting the transmitting side transmission path and the transmitting section of the own device, if the data processing device cannot send data to the transmitting side transmission path, the transmitting side transmission path and the transmitting section of the own device are connected. A modulation/demodulation device was constructed by separating the transmission section from the transmitting section and providing a switching means for connecting the receiving section to the receiving section and the transmitting section of the own device.

(Function) According to the above configuration, when the data processing device of the local station is transmitting, the receiving section and the receiving side transmission path are separated, so that the data sent from the local station arrives via the loop transmission path. Even when the data is sent to the local station, the data is not sent to the data processing device of the local station.

(Example) FIG. 1 shows an example of the present invention. 21 is a receiving section of the modem, 22 is a transmitting section, and 23 is a transmission request signal from the DTE (
24 is an inverter, 25 is a transmission line (reception side), 26 is a transmission line (transmission side) Sl, S2, S
3 is a switch controlled by R3 signal @23, T1,
T2 is a transformer.

A switch S1 and a transformer T1 are connected in cascade between the receiving section 21 and the transmission path 25, and a switch S3 and a transformer T2 are connected in cascade between the transmitting section 22 and the transmission path 26. In addition, switches S1 and S of transformers T1 and T2
The lines on the third side are connected by a switch S2. The switches 81 to S3 close when given an H level, and open when given an L level. switch S
3 is controlled by the R3 signal 23 itself, and the switch S1,
S2 is controlled by a signal obtained by inverting the R3 signal 23 by an inverter 24. Here, the switches 31 to S3 and the inverter 24 constitute a switching means 100.

The operation will be described below with reference to FIGS. 1 and 2. R
When the 8 signal 23 is in the ON state (H level), the switch S3
is closed, and the transmitter 22 sends the transmission data to the transmission line 26 via the transformer T2. At this time, the R3 signal 23 is inverted by the inverter 24 and applied to the switches S1 and S2, and the switches S1 and S2 are both opened, and the data transmitted from the own station is returned from the transmission line 25 via the transformer T1 by the loop connection. However, the receiving unit 21 does not receive it, and it is not sent to the transmission path 26 either.

Conversely, when the R3 signal 23 is in the OFF state (L level), the switch S3 is open, and the switches S1 and S2 are closed, and data sent from another station is received via the transformer T1 via the transmission line 25. The signal is input to the section 21 and sent to the transmission line 26 via the transformer T2.

[Effects of the Invention] As explained above, according to the present invention, when transmitting data from the data processing device of the own station, the receiving section and the transmission path are separated, and the data sent from the own station is looped. Even if the connection returns to the local station, the data is not input to the receiving unit. Therefore, even if a polling system using a loop connection is configured by connecting to a data processing device that determines that there is a line abnormality when receiving data sent by the local station, the system can be operated properly without system failure.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a diagram showing control of transmission output and reception input in an embodiment of the invention, and Fig. 3 is a configuration of a polling system using a loop connection. 4 are diagrams showing control of transmission output and reception input in a conventional modem. 1... CPU 2-6... DTE 7-12... Modem 13-18.25.26... Transmission line 19... Received data 21... Receiving section 22... Transmitting section 23 . . . Transmission request signal 24 . . . Inverter 31.
32, 33...Switch Tl, T2...Transformer 100...Switching means

Claims (1)

[Claims] In a modem device that modulates and demodulates a signal, which has a receiving section and a transmitting section, is connected to a receiving side transmission line and a transmitting side transmission line, and is located between these transmission lines and a data processing device belonging to its own station, wherein the data processing device When sending data to the transmitting side transmission path, the receiving side transmission path and the receiving section of the own device are separated, and the transmitting side transmission path and the transmitting section of the own device are connected, If the data processing device is unable to send data to the transmitting side transmission path, it disconnects the transmitting side transmission path from the transmitting section of its own device, and also disconnects the receiving side transmission path from the receiving section of its own device. and a switching means for connecting the transmitting side transmission line.