JPH05216782A - Interface control circuit - Google Patents

Abstract

PURPOSE:To individually control the connection/disconnection of plural slave stations, to which dizzy chain connection is executed, according to an instruction from a master station. CONSTITUTION:By generating respective select signals corresponding to plural slave stations 2-1-2-n and distributing the select signals respectively corresponding to the plural slave stations 2-1-2-n, data transfer through an internal interface bus 12, to which dizzy chain connection is executed, can be controlled in respect to the arbitrary number of slave stations. When a fault is detected at any one of the plural slave stations 21-2-n, the slave station having the fault can be disconnected from the external interface bus 12. On the other hand, since the generation of a reset signal distributed from the master station can be controlled by the select signal, the arbitrary number of slave stations can be reset from the master station 1. Further, device numbers can be applied from the master station 1 to the slave stations 2-1-2-n by device number application mode signals and the select signals.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a daisy chain connection between a master station and a plurality of slave stations via an external interface bus, and controlling data transfer between the master station and a plurality of slave stations via the external interface bus. Regarding the interface control circuit.

[0002]

2. Description of the Related Art Conventionally, when a master station and a plurality of slave stations are connected in a daisy chain and the master station transfers data to the slave stations, the master station is desired to be connected to a daisy chained external interface bus. The individual device number of the slave station is sent to select the slave station, and then the data is transferred to the corresponding slave station. Further, when data transfer is performed with a slave station different from this, similarly, the data transfer is performed after the individual device number of the slave station concerned is again transmitted and selected.

[0003]

In the above-mentioned conventional interface control circuit, when the device number is the same as that of another slave station, a conflict occurs on the daisy-chained external interface bus. There was a drawback that data could not be transferred. In addition, when the individual device number of the slave station is erroneously set, or when the device number is changed due to a failure, the data cannot be transferred to the slave station. Therefore, in such a case, it is impossible for the slave station to transfer data using the external interface bus unless the slave station resets the individual device number or replaces it with a slave station having a unique device number. There were also drawbacks. Further, when data is transferred, there is a drawback that data is transferred for each slave station, and it is not possible to collectively transfer data to an arbitrary number of slave stations. Further, when resetting the slave stations, the individual stations or the entire slave stations are reset collectively, and there is a drawback that an arbitrary number of slave stations cannot be reset collectively.

[0004]

In order to solve the above-mentioned problems, the present invention provides a selection signal generating circuit for generating a selection signal for each of a plurality of slave stations in the master station, and the generated selection signal for each slave station. A selection signal distribution interface is provided between the master station and the slave stations, and the slave station receives an external interface bus based on a selection signal distributed by the selection signal distribution interface and selecting any number of slave stations from the plurality of slave stations. A control circuit for controlling whether or not the above transfer data can be taken in is provided. Also, when a failure of any of the slave stations is detected, the master station instructs the disconnection of the slave station with the failure from the external interface bus, and selects any of the above slave stations in the slave station. A fault information transfer inhibiting circuit for inhibiting the transmission of fault information via the external interface bus based on the selection signal for performing the above is provided. In addition, a reset signal generation circuit that generates a reset signal to be sent to the slave station is provided in the master station, and the reset signal distribution that distributes the generated reset signal by converting the data on the external interface bus between the master station and the slave station. An interface is provided, and the slave station is provided with a reset control circuit that generates a reset signal based on the distributed reset signal and the selection signal for selecting the arbitrary number of slave stations. Further, the master station is provided with a device number assignment mode generation circuit that generates a device number assignment mode signal for assigning a device number to the slave station, and a device number that distributes the device number assignment mode signal between the master station and the slave station. An assigning mode distribution interface is provided, and a slave station is provided with a device number setting control circuit that captures a device number on an external interface bus based on a distributed device number assigning mode signal and a selection signal for selecting an arbitrary number of slave stations. It is a thing.

[0005]

The selection signal distributed by the selection signal distribution interface enables data transfer to any number of slave stations among the plurality of slave stations via the external interface bus. Further, when a failure of any of the plurality of slave stations is detected, the failed slave station is disconnected from the external interface bus, so that the operation of the external interface bus can be continued. Further, the master station can cause any number of slave stations to perform the reset operation. In addition, since the device number can be given from the master station to the slave station by the device number assignment mode signal and the selection signal, it is not necessary to reset the device number in the slave station, and the slave station having a unique device number can be replaced. It becomes unnecessary, and as a result, it becomes unnecessary to have the device number on the slave side.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 is a block diagram showing an embodiment of an interface control circuit according to the present invention. In the figure, 1 is a master station, and this master station 1 is composed of a central processing unit 3, an interface control circuit 4, a slave station selection signal generation circuit 5, a slave station reset signal generation circuit 6, and a device numbering mode generation circuit 7. Has been done. 2-1 to 2-n are slave stations, and the slave stations 2-1 to 2-n are interface control circuits 8-1 to 8-n and reset control circuits 9-1 to 9-1, respectively.
9-n, each device number setting control circuit 10-1 to 10-n,
It is composed of failure information data transfer inhibiting circuits 11-1 to 11-n. In addition, 12 is a daisy chain connected external interface bus, 13 is a selection signal distribution interface, 14 is a daisy chain connected reset signal distribution interface, and 15 is a daisy chain connected device numbering mode distribution interface. a is a reset signal, b is device number information,
c is fault information.

Next, the operation will be described. First, the data transfer operation via the external interface bus 12 (hereinafter, bus 12) connected in a daisy chain between the master station 1 and the slave stations 2-1 to 2-n will be described. When performing communication with the slave stations 2-1 to 2-n, the central processing unit 3 in the master station 1 provides the interface control circuit with the device number unique to the slave station device to be accessed among the slave stations 2-1 to 2-n. Instruct to 4. When accessing the slave station 2-1, for example, according to an instruction from the central processing unit 3, the interface control circuit 4 sends a device number unique to the slave station 2-1 to the bus 12. The slave station 2-1 determines whether the unique device number on the bus 12 corresponds to its own number. If it corresponds to the number of its own station, the transfer data that arrives on the bus 12 thereafter is fetched and the communication with the central processing unit 3 is started.

Next, if the central processing unit 3 wishes to communicate with the slave station 2-n, the interface control circuit 4 is sent to the slave station 2 again.
Instruct the interface control circuit 4 of a device number unique to the device of -n. When accessing the slave station 2-1, for example, according to an instruction from the central processing unit 3, the interface control circuit 4 sends a device number unique to the slave station 2-1 to the bus 12. In this case, when the slave station 2-1 in communication detects the device number unique to the slave station 2-n on the bus 12, the slave station 2-1 thereafter communicates with the bus 1.
Inhibit the transfer data from 2. However, since the unique device number on the bus 12 corresponds to the own station number, the slave station 2-n starts capturing transfer data coming from the bus 12, and the device number corresponding to the own station is the bus 1
2. Continues to capture the transfer data until it reaches the upper level.

Next, in the data transfer between the master station 1 and the slave stations 2-1 to 2-n, for example, when the slave station 2-n causes a failure and the bus 12 is affected, the bus of the slave station 2-n is interrupted. 1
The disconnection operation from 2 will be described. The central processing unit 3 in the master station 1 generates a selection signal for the slave station 2-n based on the failure information from the slave station 2-n when the slave station 2-n causes a failure and the status of the bus 12 is strange. The slave station selection signal generating circuit 5 is instructed to disconnect the slave station 2-n. The slave station selection signal generation circuit 5 that has received this disconnection instruction
Changes the connection signal of the selection signal distribution interface 13 (hereinafter, interface 13) to a disconnection signal.
When the signal of the interface 13 is changed to the disconnection signal, the interface control circuit 8-n of the slave station 2-n operates and the transfer data from the master station 1 on the bus 12 is suppressed. Further, the control circuit 8-n with the main station 1 in the own station is disabled so that it is disconnected from the bus 12. Regarding the above-mentioned disconnection operation, disconnection control of an arbitrary number of slave stations can be performed by a selection signal of the interface 13. In addition, from the master station 1 to the slave stations 2-1 to 2-n
With respect to the data transfer to, the slave 12 selects an arbitrary number of slave stations according to the selection signal from the slave station selection signal generation circuit 5.
Transfer data can be taken in from above, and therefore data transfer to any number of slave stations is possible.

Next, in the data transfer between the master station 1 and the slave stations 2-1 to 2-n, one slave station 2-n causes a failure, and failure information is being transferred to the master station 1 via the bus 12. The failure information transfer inhibiting operation of the slave station 2-n will be described. When the slave station 2-n is causing a failure, it continues to output failure information to the master station 1. Similarly to the above, the central processing unit 3 instructs the slave station selection signal generation circuit 5 to disconnect the slave station 2-n. The interface control circuit 8-n operates by the disconnection signal of the slave station 2-n via the interface 13, and the failure information data transfer suppression circuit 11-n.
On the other hand, transmission of fault information to the bus 12 is suppressed, and as a result, transmission of fault information from the slave station 2-n to the master station 1 is blocked. The failure information transmission inhibiting operation can be controlled for an arbitrary number of slave stations by the selection signal of the interface 13.

Next, in the reset instruction operation of the master station 1 and the slave stations 2-1 to 2-n, a reset instruction is issued to one of the slave stations 2-n and a reset instruction is issued to the other slave stations. Operations that are not performed will be described. The central processing unit 3 in the master station 1 instructs the slave station selection signal generation circuit 5 to output the selection signal of only the slave station 2-n to be reset. As a result, the slave station selection signal generation circuit 5 sends a connection instruction signal only to the slave stations 2-n, and sends a disconnection instruction signal to the other slave stations. The connection instruction signal and the disconnection instruction signal from the slave station selection signal generation circuit 5 are
It is distributed to the interface control circuits 8-1 to 8-n on the slave station side via the interface 13. Further, the reset instruction for the slave station from the central processing unit 3 is sent to the slave station reset signal generation circuit 6, and the reset signal distribution interface 14 is connected in a daisy chain.
To all slave stations (this operation is explained by directly connecting the slave station reset signal generation circuit 6 and a plurality of slave stations 2-1 to 2-n in a daisy chain for simplification of description. Originally, the reset signal is converted by the slave station reset signal generation circuit 6 and distributed to the plurality of slave stations via the interface control circuit 4). Then, the slave station 2-n resets itself by generating a reset signal of its own station from the above selection signal and reset signal by the reset control circuit 10-n. Regarding the reset operation on the slave station side, reset control can be performed on an arbitrary number of slave stations by a selection signal of the interface 13.

Next, in the case where two slave stations have unique device numbers between the master station 1 and the slave stations 2-1 to 2-n, when a conflict occurs on the bus 12, the master station The operation of changing the device number according to the instruction 1 will be described. Here, an example in which the device numbers of the slave stations 2-1 and 2-n compete with each other will be described. The central processing unit 3 in the master station 1 communicates with the slave stations 2-1 to 2-n via the interface control circuit 4 and the bus 12, but in this case, when an abnormal operation of the bus 12 is detected, the above processing is performed. Such slave station disconnection control is performed, and as a result, the interface control circuits 8-1 to 8-n of each slave station are controlled.
Connection instructions are given only to slave stations.

Next, the central processing unit 3 reads out the device number of the slave station connected to the bus 12. Similarly, the same processing is performed for all other slave stations, and it is recognized that the slave station 2-1 and the slave station 2-n have the same device number. In this case, the central processing unit 3 requests the device number assignment mode generation circuit 7 to change the device number. The device numbering mode generation circuit 7 includes a device numbering mode distribution interface 15 daisy-chained to all slave stations.
The change notification of the device number of the slave station is issued via. The slave station side performs a device number change processing operation by a selection signal via the selection signal distribution interface 13 and a device number change notification via the device number assignment mode distribution interface 15. That is, the device number setting control circuit 1 in each slave station
Under the control of 0-1 to 10-n, the processing for changing the device number of the own station starts.

When the slave station enters the device number change processing operation,
The central processing unit 3 sends a device number unique to the device so that the device numbers of the slave stations do not overlap with each other to the slave side via the bus 12. The slave station side takes in the unique device number transferred on the bus 12 and replaces it with the device number it had previously. Thus, the slave side has a device number unique to the device. Further, in a system in which the slave station does not have a device number unique to the device, since the device number can be set from the master station side when the system is started up, it is possible to avoid the device number conflict on the slave station side. In this way, the central processing unit 3 can control connection / disconnection of a plurality of slave stations to / from the daisy chain-connected external interface bus 12 while continuing operation of the system.

[0015]

As described above, according to the present invention,
By generating each selection signal for a plurality of slave stations and distributing the selection signals respectively corresponding to the plurality of slave stations,
Data transfer via the daisy chained external interface bus can be controlled for any number of slave stations. Further, when a failure of any of the plurality of slave stations is detected, the failed slave station is disconnected from the external interface bus, so that the operation of the external interface bus can be continued. Further, since the reset signal distributed from the master station can be generated and controlled by the selection signal, the master station can cause any number of slave stations to perform the reset operation. Further, since the device number can be given from the master station to the slave station by the device numbering mode signal and the selection signal, it is not necessary to reset the device number in the slave station, and it is not necessary to replace the slave station with a unique device number. Becomes As a result, it is not necessary to provide the device number on the slave station side.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an interface control circuit according to the present invention.

[Description of Reference Signs] 1 master station 2-1,2-n slave station 3 central processing unit 4,8-1 to 8-n interface control circuit 6 slave station reset signal generation circuit 7 device numbering mode generation circuit 9-1 to 9 -N reset control circuit 10-1 to 10-n device number setting control circuit 11-1 to 11-n fault information data transfer suppression circuit 12 external interface bus 13 selection signal distribution interface 14 reset signal distribution interface 15 device numbering mode distribution Interface a Reset signal b Device number information c Fault information

Claims (4)

[Claims] 1. An interface control circuit for daisy-chaining a master station and a plurality of slave stations via an external interface bus, and controlling data transfer between the master station and a plurality of slave stations via the external interface bus. A selection signal generating circuit for generating a selection signal for each of the plurality of slave stations is provided in the master station, and a selection signal distribution interface for distributing the generated selection signal to each slave station is provided between the master station and the slave station, The slave station is provided with a control circuit which controls whether or not the transfer data on the external interface bus can be taken in based on a selection signal distributed by the selection signal distribution interface and selecting an arbitrary number of slave stations from the plurality of slave stations. An interface control circuit characterized by being provided. 2. The interface control circuit according to claim 1, wherein when a failure of any one of the plurality of slave stations is detected, the master station disconnects the slave station in which the failure is detected from an external interface bus. And a fault information transfer inhibiting circuit for inhibiting transmission of fault information via the external interface bus based on a selection signal for selecting any number of slave stations in the slave station. circuit. 3. The interface control circuit according to claim 1, wherein a reset signal generation circuit that generates a reset signal to be sent to the slave station is provided in the master station, and a reset signal generated between the master station and the slave station. A reset signal distribution interface for converting data to a data on the external interface bus and distributing the signal is provided, and the slave station generates a reset signal based on the distributed reset signal and the selection signal for selecting the arbitrary number of slave stations. An interface control circuit, which is provided with a reset control circuit. 4. The interface control circuit according to claim 1, wherein the master station is provided with a device number assigning mode generation circuit that generates a device number assigning mode signal for assigning a device number to the slave station. And a slave station, a device numbering mode distribution interface that distributes the device numbering mode signal is provided, and the slave station receives the distributed device numbering mode signal and a selection signal for selecting the arbitrary number of slave stations. An interface control circuit comprising a device number setting control circuit for fetching a device number on the external interface bus based on the above.