JPS6120448A - Testing method of data transmitting device - Google Patents

Abstract

PURPOSE:To detect in an early state a fault on a transmission line, which cannot be detected in a usual use state, and to execute a sound operation of a data communication device by making a test data sent out by plural sub-data stations collide intentionally on the transmission line, and thereby, confirming that the device is in a state that the collision can be detected exactly. CONSTITUTION:A data station 4 informs a start of a test to a data station 1 and a data station 5, and confirms its reception. After the confirmation, the data station 4 sends out a test commanding packet to a transmission line 10. The data station 1 and the data station 5 receive the test commanding packet S0 as test packets S1, S2, respectively. Thereafter, response packets R10, R20 are sent out to the transmission line 10 immediately without executing the processing in order to avoid the collision in accordance with a rule determined in advance. If one response packet is received normally, it is decided that there is an abnormal state.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for testing a data transmission device.

In particular, the present invention relates to a method for detecting a failure in a transmission path in a data transmission device in which a large number of data stations transmit and receive data via one transmission path.

[Conventional technology]

In a data transmission apparatus in which a large number of data stations are connected to one data transmission path and transmit and receive data via this one transmission path, the large number of data stations perform data communication separately.

Therefore, it is inevitable that these data will collide and be lost on the transmission path. In order to avoid such loss, data transmission methods such as csp+Δ/CD have been devised, and many methods have been devised to avoid data collisions, and even if a collision occurs, eliminate data loss by retransmitting after a random time. I've been exposed to it. However, the possibility of a collision occurring cannot be ruled out. Therefore, conventionally, data transmission methods have been determined on the assumption that a collision will occur.

[Problem that the invention seeks to solve]

Such conventional data transmission methods are based on the premise that the transmission path is used in accordance with a predetermined standard. Therefore, if the data signal transmitted through this transmission path deviates from the standard due to signal leakage on the transmission path, deterioration of the characteristics of the drive circuit for the data station transmission path, or installation of a non-standard transmission path, etc. A problem arises.

In such a case, even if a data collision occurs on the transmission path, the data station may not be able to recognize the occurrence of the collision. As a result, the transmission procedure may be disrupted, resulting in cases in which normal data communication cannot be performed or in which data transmission takes an abnormally long time. However, even in such a case, data communication will continue normally unless a collision occurs.
The drawback was that failures that occurred in the transmission line could not be detected for a long time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method that enables early detection of such failures on a transmission path that cannot be detected under normal usage conditions, thereby enabling healthy operation of a data communication device.

[Means for solving problems]

The data transmission device testing method of the present invention is a data transmission device testing method in which three or more data stations are connected to one transmission path, and the data stations communicate with each other via this transmission path. Set one of the stations as the master station, set the two data stations other than this master station as slave stations, send test instruction data from this master station to the two slave stations, and send the test instruction data to the two slave stations. The station simultaneously transmits test data to the transmission path in response to the test instruction data, and the main station detects that the test data from the two slave stations collide on the transmission path. shall be.

[Effect]

The data transmission device testing method of the present invention intentionally collides the test data sent by a plurality of slave data stations on the transmission path, thereby confirming that the collision can be detected correctly, and then performing the conventional test. To detect failures on a transmission path at an early stage that could not be detected using other methods.

〔Example〕

FIG. 1 is a block diagram of a data communication device according to an embodiment of the present invention.

Data station 1.2.3.4.5 has transmission line 10
are connected to perform data communication with each other. In the data communication device of this embodiment, communication data on the transmission path 10 is stored in packets as defined in CCITT Recommendation X25, for example.
The packet is sent and received with information such as the type of packet, destination and source data station address added.

Here, data station 4 is assumed to be a main data station, and data station 1 and data station 5 are assumed to be sub data stations.

In this case, the data station 4 tests the transmission line 10.

First, the data stage engine 4 sends a test start notification packet to the data station 1 using a method similar to the conventional method. When the data station 1 receives this test start notification packet, it stores this information in its control unit, and further sends back a response packet to the data station 4 to notify that it has received the test start notification.

The data stage 4in4 transmits a test start notification packet to the data station 5 and receives a response packet from the data station 5 in the same manner as for the data station 1.

If an error is detected during this test start notification stage, such as not receiving a response from the data station to which the notification is being made, the data station 4 will stop the main test, record the status, and analyze the error. I do.

In this way, data station 4 notifies data station 1 and data station 5 of the start of the trial at #, and confirms the receipt thereof. f11! After recognizing the test instruction packet, the data station 4 transmits the test instruction packet to the transmission path IO.
Send to. This test instruction packet has a predetermined destination address set, and is sent to the data station that has received the test start notification.

FIG. 2 is a diagram showing the flow of a test instruction packet and a response packet thereto.

When data station 4 sends test instruction packet SO to transmission line 10, data station 1 and data station 5 receive test instruction packet SO as test packets S1 and S2, respectively.

After this, the response packets R10 and R2 are immediately sent to the transmission path 10 without performing any processing to avoid collision according to predetermined rules.
The data length of 0 is the data station and transmission line] 0
It is determined by considering the signal transmission characteristics of Therefore, when the response packets RIO and R20 are received as response packets R11 and R21 at the data station 4, they are received in duplicate, that is, in a collision, and it is not possible for both response packets R1o and R20 to be received normally. do not have.

However, if the drive circuit of the data station 5, that is, the circuit for sending data to the transmission path 10, is deteriorated, or if the transmission path from the data station 4 to the data station 5 or the transmission path beyond the data station 5 is If there is a failure such as leakage, the signal of the response packet 1121 arriving at the data station 4 becomes a signal that is attenuated compared to the response packet R11. Therefore, the data station 4 sends the response packet R1
1 is received normally. Furthermore, if the transmission path 10 is installed contrary to the rules for installing the transmission path and the distance between the data stations 4 and 5 is abnormally long, a phenomenon similar to that described above will occur, and the data station 4 will not be able to respond to the response bucket. Receive R11 normally.

Under normal usage conditions, communication is conducted in such a way that packet collisions do not occur. For this reason, even if there is an abnormality as described above, the device operates normally, and the abnormality cannot be detected by normal tests. Therefore, these failures may go undetected for a long period of time and may even lead to serious failures. In contrast, in the method of the present invention, packet collisions are intentionally caused and failures can be detected early.

Although this embodiment shows an example using data stations 1.4 and 5, other data stations can also be used. Also, data stations 1.4 and 5
After testing with data stations 1.3 and 4
It is also possible to carry out tests using the following methods and compare the test results to limit the location of the failure.

In addition, in this example, the test was carried out by specifying two slave data stations, but the slave data stations of kings and above were tested.
You can also specify a specific version for testing.

〔Effect of the invention〕

As described above, the data communication device testing method according to the present invention has the effect of discovering failures on the data transmission path that cannot be detected by normal data communication or communication tests between two data stations. Furthermore, by conducting this test regularly, it is possible to discover failures while they are minor, which has the effect of preventing serious failures from occurring.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a data communication device according to an embodiment of the present invention. FIG. 2 is a diagram showing the flow of a test instruction packet and a response packet thereto. 1.2.3.4.5...Data station, 10.
...Transmission line.

Claims (1)

[Claims] (1) In a test method for a data transmission device in which three or more data stations are connected to one transmission path and each data station communicates with each other via this transmission path, one of the data stations is Set two data stations other than this main station as slave stations, send test instruction data from this main station to the above two slave stations, and the above two slave stations respond to this test instruction data. and transmitting test data to the transmission path at the same time, and the main station detects that test data from the two slave stations collide on the transmission path. .