JPH0448300B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an SQE test signal selection and supply circuit for a multi-channel transceiver used in a local area network (LAN).

<Prior Art> Conventionally, among transceivers connected to a LAN data transmission line to transmit and receive data, there is a multi-channel transceiver configured to be connectable to a plurality of stations. This multi-channel transceiver includes an adapter that connects to one transceiver body connected to a data transmission line, and connects the transceiver body and a plurality of stations via this adapter.

By the way, one of the LAN transmission methods is
CSAMA/CD (carrier sense multiple access/
The transceivers that support the collision detection method are equipped with a data collision detection circuit to detect data collisions on the data transmission line that occur when data is transmitted simultaneously from stations connected to each transceiver. . When this data collision detection circuit detects a data collision, it outputs a collision signal consisting of a 10 MHz pulse, for example, to a collision signal line provided separately from data transmission and reception lines. When this collision signal is detected at each station, these stations stop transmitting data and transmit data again after a certain period of time, thereby avoiding data collision. Such a data collision detection circuit and collision signal line are used only when a data collision occurs; in other words, when no data collision occurs, they are in an idle state. Therefore, a transceiver equipped with an SQE test function that detects whether the transceiver is operating normally or not using such data collision detection circuits and empty states of the collision signal line has been proposed and implemented (1981). G7-11 (1984) ``SQE and JABBER''
"Ethernet transceiver with control function").

This SQE test is performed after 0.6 to 1.6 μsec has elapsed after the transceiver transmits data. By outputting this SQE test signal and having the data sending station detect this SQE test signal, the station attempts to detect that the transceiver is operating normally.

<Problems to be solved by the invention> However, such SQE test function
When attempting to prepare for the multi-channel transceiver described above, the following problems arise. That is, when data is transmitted from one of the plurality of stations connected to the multi-channel transceiver, the multi-channel transceiver receives the data and outputs the SQE test signal after transmitting the data. This SQE test signal is transmitted not only to the station that sent the data, but also to all other stations connected by the adapter. Then, this SQE test signal acts as noise for other stations that are not transmitting data, and these stations
This causes the inconvenience that the SQE test is not performed normally.

Furthermore, to be more specific, what is actually being done?
The SQE test measures the time between one station transmitting data and the next data transmission.
This is done by determining whether the transceiver is normal or abnormal depending on whether or not it receives an SQE test signal. Therefore, after a certain station transmits data, an SQE error occurs due to a transceiver failure.
Immediately after another station receives an SQE test signal output by transmitting data even though it has not received a test signal, this station will determine that the transceiver is normal. I conclude that there is.

The present invention has been made in view of the above circumstances, and an object of the present invention is to enable normal SQE tests to be performed even in multi-channel transceivers.

<Means for solving the problems> In order to achieve such an object, the present invention has the following features:
It has the following structure.

The present invention is provided in each of a plurality of stations connected to a multichannel transceiver via a transmission line, a reception line, and a collision signal line, and the transceiver outputs data transmitted from any of the stations to a data transmission line. This is an SQE test signal selection and supply circuit that selectively inputs the SQE test signal to be output to each collision signal line after the collision signal line to the transmission source station, and a data transmission detection circuit that detects data transmission from each corresponding station. means, a data transmission end detection means for detecting the end of data transmission from the station, and a data transmission end detection means for detecting the end of data transmission from the station, based on the output of the data transmission end detection means, from the time when the data transmission by the channel transceiver ends until the time when the output of the SQE test signal ends. one pulse generation means for outputting a one pulse having a pulse width longer than the time required for the one pulse; data reception detection means for detecting data reception at the station; the data transmission detection means, one pulse generation means, and data reception detection means. a signal output means for outputting a passage permission signal during a period when any one of the output signals from the output signal is given; and only during a period when the passage permission signal is inputted;
The present invention is characterized in that it includes a control means for passing the collision signal and the SQE test signal from the collision signal line to the transmission source station.

<Operation> Next, the operation of the present invention having the above-described configuration will be explained.

That is, in the SQE test signal selection and supply circuit corresponding to the station (transmission station) that transmitted data among the stations connected to the multi-channel transceiver, while the transmission station is transmitting data, and subsequently, While outputting one pulse, the AND signal output means is in a state of passing the collision signal and SQE test signal. Therefore, when a data collision occurs, a collision signal is given to the transmitting station, and an SQE test signal is also given to the transmitting station from the AND signal output means.

On the other hand, in the SQE test signal selection and supply circuits respectively corresponding to stations other than the transmitting station, the AND signal output means only during the period when data from the transmitting station is being received.
It is now in a condition to allow collision signals to pass through. Therefore, when a data collision occurs, the collision signal is given to each station, but the SQE test signal output after the transmitting station transmits data is not given to any station other than the transmitting station.

<Example> Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a schematic diagram of a transmission system using a multi-channel transceiver SQE test signal selection and supply circuit according to an embodiment of the present invention. In the figure, L is a coaxial cable which is a data transmission line,
2 is a multi-channel transceiver connected to the coaxial cable L. A plurality of stations 6 ₁ to 6 _o are connected to the multichannel transceiver 2 via an adapter 4 . This adapter 4
The data transmission line, data reception line, collision signal line, etc. connected to each station 6 ₁ to 6 _o are combined into one and connected to the multi-channel transceiver 2 . Further, within this adapter 4, SQE test signal selection and supply circuits 8 ₁ to 8 _o are provided corresponding to the respective stations 6 ₁ to 6 _o .

The specific configuration of the SQE test signal selection and supply circuits 8, ₈₁ to _8o is shown in FIG.

Data S ₁ transmitted from the stations 6, 6 ₁ to 6 _o is provided to the multi-channel transceiver 2 and also to the transmission detection section 10 as data transmission detection means. The transmission detection unit 10 outputs a detection signal _S2 at a constant level while data is being transmitted from the station 6. This detection signal S ₂
is applied to the data end detection unit 12 as a data transmission end means, and also to the OR gate G1 as a signal output means. The data end detection unit 12 detects the end of data transmission from the station 6. The detection output _S3 is given to a one-shot pulse generating section 14 as one-pulse generating means. The output pulse _S4 of the one-shot pulse generator 14 is applied to the OR gate G1.

On the other hand, the received data _S5 outputted from the multi-channel transceiver 2 is given to the station 6 and also given to the reception detection section 16 as data reception detection means. The reception detection unit 16 outputs a signal at a constant level while receiving data. This detection signal _S6 is applied to OR gate G1. The output _S7 of the OR gate G1 is input as a gate control signal to the AND gate G2 as a control means. The other input terminal of this AND gate G2 is connected to the collision signal line of the multi-channel transceiver 2, and receives the collision signal S ₈ and SQE test signal S ₉ from the multi-channel transceiver 2.
is given. The output of AND gate G2 is then given to station 6.

Next, the operation of the embodiment with the above-mentioned configuration will be explained as follows.
This will be explained with reference to the operational waveform diagram shown in FIG.

Suppose now that one of the stations 6 ₁ to 6 _o (for example, station 6 ₁ ) connected to the multichannel transceiver 2 transmits data S ₁ as shown in FIG. 3a. This data _S1 is applied to the multi-channel transceiver 2 via the adapter 4, outputted to the coaxial cable L, reflected by the multi-channel transceiver 2, and returned as a received signal _S5 . This received signal S ₅ is
All stations 6 ₁ to 6 _o via adapter 4
SQE test signal selection supply circuit corresponding to 8 ₁ to 8 _o
is input. The waveform of this received signal _S5 is d in the same figure.
is shown. Multi-channel transceiver 2
When the data transmission is finished, the
Outputs SQE test signal _S9 . This SQE test signal _S9 is also inputted to all the SQE test signal selection and supply circuits ₈₁ to _8o via the adapter 4.

On the other hand, in the SQE test signal selection and supply circuit 8 ₁ corresponding to the transmission station _{6 1} , the detection signal S ₂ shown in FIG. Data end detection unit 1
2 detects the rise of this detection signal S ₂ , that is, the end of data transmission, and supplies the detection signal S ₃ to the one-shot pulse generator 14 . As a result, the one-shot pulse generator 14 outputs the one-shot pulse _S4 shown in FIG. The pulse width of this one pulse _S4 is set to be longer than the time from the end of data transmission until the end of output of the SQE test signal _S9 .

By applying the above-mentioned reception detection signal S ₆ , transmission detection signal S ₂ and one pulse S ₄ to the OR gate G1, the gate control signal S ₇ (corresponding to the passage permission signal) shown in FIG.
is output. As a result, during the period when the gate control signal _S7 is input, the AND gate G
2 becomes active. Therefore, the SQE test signal _S9 output from the multi-channel transceiver 2 is input to the transmitting station ₆₁ via the AND gate G2. Then, this station 6 ₁ determines whether the SQE test signal S ₉ is present or not.
It is detected whether the multi-channel transceiver 2 is operating normally. Of course, if the collision signal S ₈ is transferred from the multi-channel transceiver 2 while the gate control signal S ₇ is being input to the AND gate G2, this collision signal S ₈ will be
The signal is input to the transmitting station 6 ₁ via the AND gate G2, and based on this, the station 6 ₁ stops transmitting data.

On the other hand, each SQE test signal selection supply circuit 8 of the other stations 6 ₂ to 6 _o that are not transmitting data
Since the transmission detection signal S ₂ and one pulse S ₄ are not output at ₂ to 8 _o , each AND gate G2 of these SQE test signal selection and supply circuits 8 ₂ to 8 _o
is active only during the period of the reception detection signal _S5 . Therefore, during this period, AND gate G
Only the collision signal _S8 passes through station 2, and the SQE test signal _S9 is not input to stations ₆₂ to _6o . From this, stations 6 ₂ to 6 _o are prohibited from transmitting data due to the input collision signal S ₈ , but SQE based on data transmission from other stations (in this case, station 6 ₁ ) is prohibited. It is understood that no false SQE test with test signal _S9 is performed.

In the above-described embodiment, the SQE test signal selection and supply circuit 8 is configured in terms of hardware, but the present invention is not limited to this, and can be configured in software using a microcomputer. Also includes things.

<Effects of the Invention> As is clear from the above description, the SQE test signal selection and supply circuit for a multi-channel transceiver according to the present invention includes means for detecting data transmission and data reception from the station, and also detects the end of data transmission. It is equipped with means for generating one pulse of a certain time width after detection, and the collision signal,
Since the passage of the SQE test signal is controlled, only the SQE test signal selection and supply circuit corresponding to the station that sent the data can detect the collision signal and the SQE test signal.
The SQE test signal selection and supply circuit corresponding to the station that passes the test signal and does not transmit data passes only the collision signal and does not pass the SQE test signal.

Therefore, according to the present invention, this type of multi-channel transceiver can be used without causing the inconvenience that other stations perform erroneous SQE tests due to SQE test signals based on data transmissions of other stations. The reliability of the data transmission system can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the configuration of a system using an SQE test signal selection and supply circuit for a multi-channel transceiver according to an embodiment of the present invention, and FIG. 2 is a specific diagram of the SQE test signal selection and supply circuit 8 according to the embodiment. FIG. 3 is an operational waveform diagram of the SQE test signal selection and supply circuit 8. 2...Multi-channel transceiver, 4...Adapter, 6,6 ₁ to 6 _o ...Station, 8,8 ₁
~8 _o ...SQE test signal selection supply circuit, 10...
...Transmission detection section, 12...Data end detection section, 14
...One-shot pulse generator, 16...Reception detection section, G1...OR gate, G2...AND gate.

Claims (1)

[Claims] 1 A multichannel transceiver is provided at each of a plurality of stations connected via a transmission line, a reception line, and a collision signal line, and the transceiver transmits data transmitted from any of the stations. This is an SQE test signal selection and supply circuit that selectively inputs the SQE test signal that is output to each collision signal line after being output to the line to the transmission source station, and detects data transmission from the corresponding station. data transmission detection means; data transmission end detection means for detecting the end of data transmission from the station; and based on the output of the data transmission end detection means, the SQE test signal is detected from the time when the data transmission by the multi-channel transceiver ends. one-pulse generation means for outputting a one-pulse having a pulse width longer than the time required to complete the output; data reception detection means for detecting data reception at the station; the data transmission detection means, one-pulse generation means; a signal output means for outputting a passage permission signal during a period when any one of the output signals from the data reception detection means is given; and only during a period when the passage permission signal is inputted;
An SQE test signal selection and supply circuit for a multi-channel transceiver, comprising: control means for passing a collision signal and an SQE test signal from the collision signal line to a transmission source station.