JPH0650866B2 - Token passing bus test equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is used for testing a token passing system.
The present invention is used for a test of a system in which a plurality of communication devices are connected to one token passing bus and the communication devices communicate with each other.

The system to be tested by the present invention is a system in which a plurality of communication devices are connected to one token passing bus (see, for example, FIG. 2), and the plurality of communication devices have different sequences. Number (eg # 0- #
n) is set, tokens each including one sequence number are transmitted in time series to the token passing system bus, and a plurality of communication devices each receive a token coming to the token passing system bus and include it in the token. It is set so that it can write the information (obtain the transmission right) in the area for writing the communication information of the token when the sequence number is monitored and when the sequence number matches the preset sequence number of the self device. It is a system that has been.

The device of the present invention is a test device which is used by connecting to a bus of such a system when a test is executed, and whether or not a plurality of communication devices connected to the bus normally perform the token passing operation. It is a device for performing such a test.

〔Overview〕

The present invention relates to a bus test apparatus that communicates between a plurality of apparatuses connected to a token passing system bus, by transmitting tokens having different sequence numbers sequentially from an increment circuit provided in this test apparatus, The token passing test of the test equipment is carried out by one test equipment so that the cost and the occupied area can be saved.

[Conventional technology]

In the token-passing type bus, data to which a special code called a SYNC code is added among the data on the bus is treated as a control word. The device connected to the bus transmits and receives based on this control word. Each device connected to the bus has a unique sequence number, and when a token of a control word having the same number as this sequence number appears on the bus, the corresponding device obtains transmission / reception.

The device which has acquired the transmission right inserts data between the control word (hereinafter referred to as BOM) indicating the beginning of the data and the control word (hereinafter referred to as EOM) indicating the end of the data and sends the data to the bus if there is data to be transmitted. . At this time, a function code indicating the data receiving destination is added to the BOM, and the device connected to the bus checks the function code when it detects the BOM, confirms that it is the data to be received, and receives the data. To do.

The device having the transmission right adds the value incremented by +1 to its own sequence number and sends the token onto the bus in order to end the transmission or pass the transmission right to another device if there is no data to be transmitted. The sequence number is set when the power is turned on or when a reset instruction is issued.When the token does not appear on the bus within the specified time, the sequence number of the token immediately before the timeout is set to your own sequence number. I am trying. When the time-out occurs, the device with sequence number 0 (zero) acquires the transmission right.

As described above, the sequence number to be acquired is determined depending on the number of devices connected to the bus. For example, 0 to 3 when 4 devices are connected
Is.

[Problems to be solved by the invention]

As described above, the sequence number of the token in the conventional token passing system is determined by the number of devices connected to the bus. Therefore, if the number of bits indicating the sequence number is 8 bits, it is not possible to determine whether token passing is normal unless there are 2 ⁸ (256) devices. Further, it is necessary to have the maximum number of devices that can be inspected and the like, which requires enormous cost and a large floor for installing these devices.

The present invention solves such a problem, and an object of the present invention is to provide an apparatus capable of performing a token passing test with a single test apparatus.

[Means for solving problems]

The present invention is a driver / receiver that is connected to a token passing bus to which a plurality of communication devices are commonly connected, and that transmits / receives data to / from a device under test among the communication devices, and a token for the driver / receiver. In a token-passing bus test apparatus equipped with a token transmission register for giving a token and a token reception register for temporarily storing the token received by the driver / receiver, the sequence number of the token to be transmitted is the sequence number of the token transmitted immediately before. An increment circuit for adding a constant value to the sequence number and setting it, a comparison circuit for comparing the contents of the token transmission register and the token reception register, and a display circuit for displaying the comparison result of the comparison circuit. Characterize.

[Action]

When testing the device that is communicating between each device connected to the token passing system bus, the control circuit first initializes the token transmission register 23, and the device under test is connected to the bus via the driver / receiver. A control word for initial setting is transmitted for initialization, and the token of the token transmission register is sent to the bus.

The device under test obtains the transmission right by receiving this token, and if there is no data to transmit, increments its own sequence number by +1 and transmits the token to the next device. At this time, the driver / receiver receives the token from the device under test and sets it in the talk reception register, the comparison circuit compares and judges this value and the value obtained by adding 1 to the content of the token transmission register, and the display circuit displays the result. indicate. After the operation is completed, the control circuit uses the increment circuit to increment the content of the token transmission register.

That is, a token is transmitted to the device under test, then the token transmitted by the device under test is received, and it is tested whether the token transmitted by the device under test is normal. In this way, a single testing device can test the token passing bus between a plurality of devices.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 2 is a diagram showing a general system example of a token passing system bus.

The token passing bus system is generally constructed by connecting a plurality of devices # 0 to #n to a token passing bus 10 as shown in FIG.

In the embodiment of the present invention, as shown in FIG. 1, the test apparatus 1 is connected to the token passing system bus 10 to test whether the token passing of the device under test 2 is correct.

The test apparatus 1 includes a driver / receiver 20 as a transmission / reception means for exchanging data with a device under test 2 connected to a token passing bus (hereinafter referred to as a bus), and a token transmission register 23 for transmitting a token. , An increment circuit 26 that sequentially increments the value of the token to be transmitted, a token reception register 21 that stores the received token, a comparison circuit 24 that compares the contents of the token transmission register 23 and the token reception register 21, and the comparison result. A display circuit 25 for displaying, a driver / receiver 20, a token transmission register 23, a token reception register 21, a comparison circuit 24 and a control circuit 22 for controlling the display circuit 25 are provided, and the device under test 2 transmits to the comparison circuit 24. It includes means for determining whether the token to be played is normal.

Next, the operation of the embodiment of the present invention will be described.

First, before the test, the control circuit 22 uses the token transmission register 23
Is initialized. After that, the control circuit 22 transmits a control word for initializing the device under test 2 to the bus 10 via the driver / receiver 20. Upon receiving the control word, the device under test 2 performs initialization. Next, the control circuit 22 sends the token of the token transmission register 23 to the bus 10. After the token is transmitted to the bus 10, if the token is not received within the specified time, the control circuit 22 again controls the token transmission register 23.
Send the token set to.

The device under test 2 uses the sequence number of the token immediately before the time-out when the initialization is completed as described above as the sequence number of the device itself. After that, when a token is sent from the test device 1, the device under test 2 obtains the transmission right, and if there is no data to be transmitted, increments its own sequence number by +1 and transmits the token to the next device. For example, if the test apparatus 1 sends a token with the sequence number “5”, the sequence number of the apparatus under test 2 is “5” and the apparatus under test 2 has the sequence number “6”.
Send the token to the device.

At this time, the token from the device under test 2 is received by the driver / receiver 20 of the test device 1, and the token reception register 21
Set to. The token reception register 21 is connected to the comparison circuit 24. The other data of the comparison circuit 24 is connected to the token transmission register 23. The comparison circuit 24 compares the value obtained by adding 1 to the content of the token transmission register 23 and the data of the token reception register 21, and notifies the display circuit 25 of the result. The display circuit 25 displays the result according to the notification from the comparison circuit 24. When the above operation is completed, the control circuit 22 uses the increment circuit 26 to increment the contents of the token transmission register 23, and repeats the above procedure in sequence.

〔The invention's effect〕

As described above, according to the present invention, the token passing test of the device under test can be performed by one test device by sequentially transmitting the tokens having different sequence numbers from the test device. Therefore, the cost is reduced and the floor occupying area is also reduced as compared with the conventional case in which the maximum possible number of devices must be owned.

INDUSTRIAL APPLICABILITY The present invention is effective in the case where continuous sequence numbers are set in a plurality of communication devices to be the device under test and the plurality of communication devices are sequentially and continuously tested.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a diagram showing a general system example of a token passing system bus. 1 ... Test device, 2 ... Device under test, 10 ... Token passing bus, 20 ... Driver / receiver, 21 ...
Token receiving register, 22 …… Control circuit, 23 …… Token sending register, 24 …… Comparison circuit, 25 …… Display circuit, 26
...... Increment circuit.

Claims (1)

[Claims] 1. A system comprising a plurality of communication devices connected to one token passing bus (10), wherein different sequence numbers (# 0 to #n) are set to the communication devices. , Tokens each including one sequence number are time-sequentially transmitted to the token passing bus (10), and the communication device receives the tokens arriving at the token passing bus (10) and receives the tokens. The token passing system bus (10) for monitoring the sequence number included in the above, and testing the system set to acquire the transmission right for the token when the sequence number matches the sequence number set in the self. In the test device (1) connected to the token passing system bus (1 0) a driver / receiver (20) for transmitting / receiving a token, and a token transmission register (23) for temporarily holding a token given to the driver / receiver (20) for transmission.
And a token reception register (21) for temporarily holding the token received by the driver / receiver (20), and an attempt is made to test the sequence number of the token held in the token transmission register (23). A setting circuit (26) for setting the sequence number set in the device under test (2), which is one of the plurality of communication devices, and the token transmission register (23). A comparison circuit (24) for comparing the content of the transmitted token with the content of the token which is temporarily held in the token reception register (21) and which the device under test (2) responds to the transmitted token. And a display circuit (25) for displaying the comparison result of the circuit (24). An incrementer circuit that holds the value immediately before that added by a fixed value to the sequence number that has been set in the token that was previously held by the driver (23) and was already sent from the driver / receiver (20) and that is the sequence number of the token to be sent next Token passing bus test equipment characterized by including.