JPH0650867B2 - 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 (for example, # 0 to #
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〕

According to the present invention, in a bus test device for performing communication between a plurality of devices connected to a token passing system bus, a token having a different sequence number is sequentially transmitted from a setting means provided in the test device. 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 gets the transmission right.

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 relates to a driver / receiver which is connected to a token passing system bus to which a plurality of communication devices are commonly connected, and which transmits / receives data to / from a device under test among the communication devices, and to the driver / receiver. In a token passing register test device including a token transmission register for giving a token and a token reception register for temporarily storing the token received by the driver / receiver, stored in the token reception register as a sequence number of a token to be transmitted. It is characterized by further comprising means for setting according to the sequence number, 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.

[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 token reception register, the comparison circuit compares this value with the value obtained by adding 1 to the content of the token transmission register, and the display circuit displays the result. To do. After the operation is completed, the control circuit transfers the contents of the token reception register to 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. , Token reception register as the sequence number of the token to send
Setting means 26 for setting according to the sequence number stored in 21, a token reception register 21 for storing the received token, a comparison circuit 24 for comparing the contents of the token transmission register 23 and the token reception register 21, and the comparison result thereof. Display circuit 25 for displaying and driver / receiver
20, token transmission register 23, token reception register 2
1, the control circuit 22 for controlling the comparison circuit 24 and the display circuit 25
The comparison circuit 24 includes means for determining whether or not the token transmitted by the device under test 2 is normal.

Next, the operation of the embodiment of the present invention will be described. First, before the test, the control circuit 22 initializes the token transmission register 23. 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 transmits the token set in the token transmission register 23 again.

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.

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
Set to 21. The token reception register 21 is a comparison circuit 24
Connected to. 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 transfers the contents of the token reception register 21 to the token transmission register 23 and repeats the above procedure sequentially.

〔The invention's effect〕

As described above, according to the present invention, by transmitting tokens having different sequence numbers sequentially from the test device, the token passing test of the device under test can be performed by one test device, and conventionally, Although it was necessary to have the maximum number of devices that could be taken, it is sufficient to use only one test device, which has the effect of reducing the cost and occupying the floor area. INDUSTRIAL APPLICABILITY The present invention is useful when continuous sequence numbers are set in a plurality of communication devices to be the device under test and the plurality of communication devices are continuously tested, and the sequence number raising operation of the device under test is performed. If is normal, continuous testing can be performed.

[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
…… Setting means.

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 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 equipment (1) connected to the Change the sequence number of the token to the sequence number of the received token by adding "1" when the sequence number of the received token matches the sequence number set in the self and there is no information to be transmitted to the self. A driver / receiver (20) for transmitting / receiving a token to / from the token passing bus (10), and a token transmission register (23) for temporarily holding a token to be transmitted to the driver / receiver (20).
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). A token passing system bus including means for setting the sequence number of the token responded by the device under test held by the register (21) as the sequence number of the device under test (2) to be tested. Test equipment.