JPH0454041A - Balanced transmission receiver circuit - Google Patents

Abstract

PURPOSE:To convert a data into a data with a substantial correct polarity automatically even when the polarity of connection between a transmission cable and a receiver circuit is wrong by controlling the polarity of the receiver depending on the significance of the received data. CONSTITUTION:A reception data 22 is branched into two, the one is given to a significance discrimination circuit 23. The significance discrimination circuit 23 discriminates the significance of the received data by referencing a data pattern storage table 28 so as to check whether or not the received data 22 is a data having a pattern stored in the table and estimated in advance. A polarity conversion command circuit 25 generates a polarity control signal 27 in response to the result of discrimination and gives it to a polarity conversion circuit 15. The polarity conversion circuit 15 keeps the switch connection state as it is when the received polarity control signal 27 is at an L level and throws its contacts so that common terminals 18,19 are connecte respectively to contacts 11,13 when at an H level.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a receiver circuit for balanced transmission, and for example, to a balanced transmission receiver circuit used for data transmission for transmitting a limited number of commands.

[Conventional technology]

In general, data transmission is often carried out by so-called balanced transmission using two transmission cables, rather than a single transmission cable. For example, in a monitoring system that monitors and reports the operation of a certain device, the types of commands used for reporting are limited, but ensuring reliability is particularly important, so balanced transmission is often used.

FIG. 2 shows a receiver circuit in conventional balanced transmission. As shown in this figure, balanced transmission is carried out on two transmission cables (not shown) and two input terminals 31.3
The data input from 2 is received by the receiver circuit 33 and taken in as received data 34 into an internal circuit (not shown).

[Problem to be solved by the invention]

In this way, in conventional balanced transmission receiver circuits, the two input terminals are directly connected to two transmission lines, so if the polarity of the transmission cable is accidentally connected due to construction etc., the data The disadvantage was that it would no longer be possible to receive

SUMMARY OF THE INVENTION An object of the present invention is to provide a balanced transmission receiver circuit that can automatically convert the polarity correctly and receive data even if the connection polarity of a transmission cable is incorrect.

[Means to solve the problem]

In the invention as claimed in claim 1, (i) data for determining whether data having a predetermined polarity received through a transmission line including a plurality of transmission cables is data of a previously expected pattern; (11) a connection polarity for switching the connection polarity of the transmission cables of the plurality of transmission paths when the data pattern determination means determines that the pattern of the received data is not a previously expected pattern; The balanced transmission receiver circuit is provided with a converting means.

In the first aspect of the invention, received data is monitored, and when the received data does not belong to a predetermined data pattern, the polarity of the connected transmission cable is automatically switched.

In the invention according to claim 2, (i) a receiver circuit that receives a signal balanced and transmitted with a predetermined polarity on two paired transmission cables; (ii) two input terminals of this receiver circuit; a polarity conversion circuit that converts the polarity of the connection relationship between the two paired transmission cables; (ii)
(i) a data no. (turn memory table) storing a pattern of received data expected in advance; and (iv) a data pattern output from the receiver circuit matches one of the data patterns stored in the data no. turn memory table. (V) a data pattern determination circuit for determining whether or not the data pattern determination circuit determines whether the data pattern from the receiver circuit matches any of the data patterns stored in the data pattern storage table; If not, the balanced transmission circuit is provided with a polarity conversion instruction circuit that instructs the polarity conversion circuit to perform polarity conversion.

In the invention as claimed in claim 2, when the pattern of the received data does not match any of the data patterns registered in advance in the data pattern storage table, the polarity conversion circuit is operated to connect the transmission cable and the receiver circuit. Let's switch the polarity.

〔Example〕

The present invention will be described in detail with reference to Examples below.

FIG. 1 shows a balanced transmission receiver circuit in one embodiment of the present invention. This circuit has contacts 11-14.
A polarity conversion circuit 15 having a contact point 1 is provided.
2.13 is connected to the input terminal 16, and the contact 11.14 is connected to the input terminal 17.

Also, common terminal 18 for contacts 11, 12 and common terminal 19 for contacts 13, 14 are connected to receiver 210 input terminals A, B, respectively.

This receiver 21 receives data input from a transmission cable (not shown) via input terminals 16 and 17 and the polarity conversion circuit 15, and outputs received data 22. This received data 22 is branched into two parts, one of which is input to a reception data processing circuit (not shown) and the other to a significance determination circuit 23. A data pattern storage table 28 for storing patterns of received data expected in advance is connected to this significance determination circuit 23, and the output side is connected to a polarity conversion circuit I5 via a polarity conversion instruction circuit 25. There is.

The operation of the balanced transmission receiver circuit configured as above will be explained. Here, in the initial state of the switch of the polarity conversion circuit 15, the common terminals 18 and 19 are connected to the contacts 12 and 19, respectively.
14 side.

Input data manually entered through input terminals 16 and 17 is input to receiver 210 input terminals A and B via contacts 12 and 14 of polarity conversion circuit 15, respectively. The receiver 21 that has received the input data outputs it as received data 22. This received data 22 is branched into two parts, one of which is input to the significance determination circuit 23.

The significance determination circuit 23 determines the significance of the received data by referring to the data pattern storage table 28 and checking whether the received data 22 corresponds to a previously predicted pattern stored in this table. judge. Determination result information 26 indicating the result is sent to the polarity conversion instruction circuit 25.

Upon receiving this, the polarity conversion instruction circuit 25 creates a polarity control signal 27 according to the determination result and supplies it to the polarity conversion circuit 15. For example, when it is determined that there is significance, that is, when the pattern of the received data 22 matches any of the data patterns stored in the data pattern storage table, the level is "L". Otherwise, the polarity is "H" level. A control signal 27 is created and output.

In the polarity conversion circuit 15, when the supplied polarity control signal 27 is at "L" level, the connection state of the switch is maintained as it is, and when it is at "H" level, the common terminals 18 and 19 are connected to the contact points 11 and 13, respectively. Switch to connect.

As a result, the input terminals 16 and 17 are connected to the receiver 2, respectively.
It is connected to input terminals B and A of 1, and the polarity of input data is inverted.

At this time, that is, when the received data 22 is determined to have significance, the determination result information 26 output from the significance determination circuit 23 is also sent back to the transmitting side. As a result, the data determined to be significant is retransmitted from the sending side,
From the next time onwards, you will be able to receive it normally.

〔Effect of the invention〕

As explained above, according to the present invention, the polarity of the receiver is manipulated based on the significance of the received data, so even if the connection polarity between the transmission cable and the receiver circuit is incorrect, the original correct polarity is automatically applied. It can be converted to polarity and can be received correctly. Therefore, it is particularly effective in cases where errors in cable connection polarity are likely to occur, such as in systems that frequently involve connection work on transmission cables.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a balanced transmission receiver circuit according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional balanced transmission receiver circuit. 5...Polarity conversion circuit, 6.17...Input terminal, 21...Receiver, 3...Significance determination circuit, 5... -Polarity control circuit, 8...Data pattern storage table. Applicant NEC Corporation Representative Patent Attorney Umeo Yamauchi

Claims (1)

[Claims] 1. Data pattern determining means for determining whether data having a predetermined polarity received via a transmission path consisting of a plurality of transmission cables is data of a previously expected pattern. and connection polarity switching means for switching the connection polarity of the transmission cables of the plurality of transmission lines when the data pattern determination means determines that the pattern of the received data is not a previously expected pattern. A balanced transmission receiver circuit characterized by: 2. A receiver circuit that receives a signal balanced and transmitted with a predetermined polarity on two paired transmission cables, and two input terminals of this receiver circuit and the paired two transmission cables.
a polarity conversion circuit that converts the polarity of connection with the main transmission cable; a data pattern storage table that stores expected received data patterns in advance; and a data pattern that is output from the receiver circuit is stored in the data pattern storage table. a data pattern determination circuit that determines whether the data pattern matches any of the stored data patterns; and as a result of the determination by the data pattern determination circuit, the data pattern from the receiver circuit is stored in the data pattern storage table. A balanced transmission receiver circuit comprising: a polarity conversion instruction circuit that instructs the polarity conversion circuit to perform polarity conversion when the polarity conversion circuit does not match any of the data patterns.