JPH11272601A - Cascade-connected card, id allocation method in system constituted of the card and bus using right priority judgement method for common bus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ID allocation method for automatically allocating an ID to cascade-connected respective cards and the bus using right priority judgement method of a common bus. SOLUTION: The respective cards 10A-10D are cascade-connected and the card 10A of the most front stage is connected to a start end value setting part 2. The respective cards 10 are provided with an ID storage part 11 and an adder 12. The card 10A inputs a prescribed start end value (O) outputted from the start end value setting part 2 and stores the input value (0) in the ID storage part 11 as its own ID first. Also, the input value (0) is also inputted to the adder 12 and a value (1) for which +1 is added by the adder 12 is outputted to the card 10B of a poststage. Thereafter, similarly in the cards 10B, 10C and 10D, the input value from the card of their preceding stage is obtained as their own ID, +1 is added to the input value and it is outputted to the card of their poststage. Also, from an output value from the card 10D of a last stage, the number of the connected cards is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ID assigning method in a system in which a plurality of cards are cascade-connected to form a common bus, and a bus use right priority determining method for the common bus.

[0002]

2. Description of the Related Art When a system is constructed using a plurality of small board boards (hereinafter, referred to as cards) each mounting a predetermined circuit, a common bus for interfacing input / output signals of the plurality of cards is usually required. It is. Conventionally, there are a method of connecting each card to a base board (motherboard) on which a common bus is mounted, and a method of configuring a common bus by cascading each card without using the base board (hereinafter, this card is referred to as this card). Is also called a cascade connection card).

[0003] An ID for identification is uniquely assigned to each card, and arbitration of the right to use the bus and assignment of addresses on the bus are performed based on the ID. FIG.
FIG. 3 is a diagram showing an example of a configuration in the case of using a base board and explaining an ID assignment method thereof.

In FIG. 1, a plurality of connectors 101 to 104 are provided on a base board 100 on which a common bus is mounted, and an ID is assigned to each connector in advance. In the example shown in FIG.
= 1, ID = 2 for connector 102, ID = 3 for connector 103, and ID = 4 for connector 104. Thus, by connecting each of the cards 110 to 140 (by each of the connectors 111 to 141) to any one of the connectors on the base board 100, the card can acquire the ID assigned to the connection destination connector. I can do it. In the example shown in the drawing, the card 110 connected to the connector 101 acquires ID = 1 assigned to the connector 101 in advance. Similarly, card 120 has ID = 2, card 1
30 acquires ID = 3, and the card 140 acquires ID = 4.

FIG. 8 shows an example of a configuration when a cascade connection card is used, and is a diagram for explaining an ID assignment method. In FIG.
Have buses 152 to 182, and cascade-connect each card by connectors 153 to 184 to connect the buses, thereby forming a common bus 190.

The cards 150 to 180 have rotary switches 151 to 181 respectively, and a designer or the like operates the rotary switches to set the ID of each card.

At the time of operation of the system constructed as described above, arbitration of the right to use the bus is performed using the ID assigned to each card. The bus use right arbitration method includes a method of performing the bus use right priority determination within each card and a method of performing the bus use right outside the card.

MULTIBUS II (IEEE / ANSI1296) is known as a method of making a bus use right priority determination in each card. This is a method in which a card that wants to input and output data using a common bus uses a wired or configured arbitration bus to make a priority determination on the right to use the bus. In this method, the own ID is output to an arbitration bus, and the value is input while performing wired OR on this bus,
The IDs are compared one by one, and the ID output is stopped from the card that lost the arbitration, and the card that has continued the ID output to the end becomes the winner and obtains the right to use the bus. In this method, it is possible to connect up to the number of cards represented by a power of 2 of the number of arbitration buses.

FIG. 9 is a diagram for explaining a method of making a bus use right priority determination outside a card. Although not particularly shown in the figure, each card 210 is substantially similar to the case of FIG.
240 have an internal bus, and the common bus 190 is formed by cascading the respective cards and connecting the respective internal buses.

[0010] FIG. 9 further includes a priority judging section 200 for judging a bus use right priority outside the card. Each card has a request line and a response line for the priority determination unit 200. That is, the request lines A to D for outputting a request signal to the priority determination unit 200 and the priority determination unit 20
0 is a response line E to notify each card of the priority determination result.
H. There are various methods of determining the priority of using the bus in the priority determination section 200, but they are not specifically described here.

[0011]

In the method of assigning IDs in the above-mentioned ID assigning method, IDs are assigned to the respective connectors on the base board in advance, and it is necessary to prepare the base board in advance according to the maximum number of mounted cards. . Because of this,
In particular, even when a system is constructed with a small number of cards, there is a problem that the system cannot be downsized because the overall size is determined by the size of the base board.

On the other hand, when a system is constituted by cascaded cards, the size of the system is determined by the number of cards, but it is not possible to assign IDs to the connectors in advance. I
D was assigned. For this reason, the switch operation and the like must be performed manually, which is troublesome, and there is a risk that ID duplication due to human error may occur.

[0013] In the bus use right priority determination method,
The method using the MULTIBUS II requires a function of determining the value of the arbitration bus one by one using a wired OR at a relatively low speed, and has a problem that the circuit configuration becomes complicated.

On the other hand, in the method of performing the bus use right priority determination outside the card, since one request line and one response line are required for each card, an arbitration signal line twice as many as the number of connected cards is required. Will be. Conversely, there has been a problem that only half of the number of arbitration buses can be connected to the card.

An object of the present invention is to automatically assign an ID to each cascaded card in a system in which a plurality of cards are cascaded to form a common bus.
It is an object of the present invention to provide a D assignment method and a bus use right priority determination method capable of fairly distributing the common bus use right of each card with a simple configuration.

[0016]

According to the present invention, there is provided a cascade connection card according to the present invention, wherein a plurality of cards are cascaded to form a common bus, and in each of the cards, an input value input from a preceding card is changed by a predetermined value. There are changing means for changing the value according to the rules and outputting the changed value to a subsequent card, and ID storage means for storing the input value or the value changed by the changing means as its own ID.

According to the present invention, there is provided an ID assigning method for automatically assigning an ID to each card in a system in which the cards are cascaded to form a common bus by using the cascade-connected cards having the above-described structure, and a simple structure. It is possible to realize a bus usage right priority determination method capable of fairly distributing the bus usage right of each card.

An ID assigning method according to the present invention is an ID assigning method in a system in which a plurality of cards are cascaded to form a common bus, in which a predetermined initial value is input to the cascaded front-end card, In the first-stage card, a value after change obtained by changing the input initial value according to a predetermined change rule or the initial value is stored as its own ID, and the changed value is output to a subsequent card, Until the last card, in each card, a value obtained by sequentially changing a value input from the previous card according to the predetermined change rule or the input value is stored as its own ID, and the value after the change is stored. An ID is assigned to each card connected in cascade by outputting the data to the subsequent card.

According to the above-described ID assignment method, the system can be downsized (the size of the base board is not limited).
In a system configuration using a cascade connection card, which is a system, an ID is automatically assigned to each card without having to manually set an ID or the like. As a result, it is possible to perform ID assignment without any trouble and no mistake.

Further, for example, the number of cards in the cascade connection can be automatically detected based on the output value of the last card, the initial value, and a predetermined change rule. This is because, for example, if the initial value and a predetermined change rule are known, a table or the like showing the relationship between the output value of the last card and the number of connected cards is stored, so that the output value of the last card is stored. Is detected and the number of connected cards can be determined by referring to the table or the like.

The bus use right priority judging method according to the present invention comprises:
A bus use right priority determination method for a common bus in a system in which a plurality of cards are cascaded to form a common bus, wherein the bus use right arbitration control means inputs an initial value to be input to a cascaded front-end card. Is changed in a predetermined cycle in accordance with a predetermined rule, so that the value held by each card is sequentially changed, and a cascade connection card holding a predetermined value is set as a bus of the common bus at that time. Have the right to use.

According to the above bus use right priority determination method, the fairness of the bus use right can be distributed to each card with a simple circuit structure without complicating the circuit structure. Also,
In the bus use right priority determination method, for example, the bus use right arbitration control means, when a specific event occurs,
The initial value is changed so that the right to use the common bus passes to a card having a function dedicated to the specific event.

The occurrence of the above-mentioned specific event is, for example, the occurrence of an abnormality. The right to use the common bus is temporarily transferred to a card having a function dedicated to dealing with the abnormality. Can be.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram for explaining an ID assignment method according to the present embodiment, and shows an example of a system in which each card is cascaded.

In FIG. 1, the card 10A is stored in the starting value setting unit 2.
Is connected, the card 10B is connected to the card 10A,
Hereinafter, similarly, the card 10C and the card 10D are cascaded.

Each of the cards 10A to 10D has an internal bus 16 in substantially the same manner as in the related art, and cascade-connects the cards 10A to 10D by connectors (connectors 17 and 18) to connect the common bus 1. Form.

Each of the cards 10A to 10D further includes an ID storage unit 11, an adder 12, an input connector 13, an output connector 14, and an arbitration bus 15. The input connector 13 is an output connector 14 of the preceding card.
(Only the first card is connected to the start value setting unit 2), and is connected to its own previous card (only the first card is set to the start value setting unit 2).
The data to be output is input. The input data is input to the ID storage unit 11 and the adder 12 via the arbitration bus 15. The ID storage unit 11 is a storage area for storing its own ID, and recognizes the value stored here as its own ID. Adder 12
Is output by adding +1 to the input value, for example, and the addition result is output from the output connector 14 to a card at a subsequent stage. In the figure, arbitration bus 15 (arbitration bus 3)
Has two bits, and a maximum of four cards can be connected (ID can be assigned). When the arbitration bus 15 is 3 bits, a maximum of 8 cards can be connected, and when the arbitration bus 15 is 4 bits, a maximum of 16 cards can be connected.

The start value setting unit 2 sets / stores a value (start value) to be input to the card (10A) at the first stage of the cascade connection, and outputs this start value as necessary.

In the above configuration, when the start value (for example, “0”) is output from the start value setting unit 2 and input to the card 10A, the input value “0” is stored in the card 10A as an ID.
Stored in the storage unit 11. From this, the card 10A is
This means that “0” has been acquired as the self ID value. The input value “0” is also input to the adder 12. The adder 12 performs an operation of adding +1 to the input value “0”. The value “1” after the addition processing is output to the card 10B at the subsequent stage of the self. Similarly, in the card 10B, by storing the input value "1" in the ID storage unit 11, "1" is acquired as its own ID value, and the adder 12 adds +1 to the input value "1". The value “2” is output to the card 10C at the subsequent stage. Hereinafter, similarly, the card 10C acquires "2" as its own ID value, and the card 10D acquires "3" as its own ID value.

In FIG. 1, an adder 12 is provided in each card 10.
Is provided to add +1 to the input value. However, the present invention is not limited to this. For example, a subtractor may be provided instead of the adder 12 to subtract -1. In short, any configuration may be used as long as the input value is changed according to a certain rule (hereinafter, referred to as a change rule) and output to a subsequent card. In addition, FIG. 1 shows only a configuration common to each card related to the description of the present embodiment, and does not particularly show other circuits and the like. There is also a driver or the like for performing the above.

As described above, according to the ID assigning method of the present embodiment, in a configuration in which the cards are cascaded to form a common bus, the ID assigning of each card is automatically performed. The size of the system is not determined by the size of the baseboard,
There is no need for manual labor, and no ID duplication due to human error occurs.

Further, as described above, when it is desired to increase the maximum number of connectable cards, it is possible to cope only by increasing the number of bits of the arbitration bus 15. The maximum number is 4
Since the number of cards can be increased from eight to eight (the power can be increased by a power of 2), the amount of hardware can be hardly increased even if the number of cards to be handled becomes very large.

In the configuration shown in FIG. 1, the number of connected cards can be detected in addition to the automatic assignment of IDs. That is, if the "change rule" is known, the number of connected cards can be determined based on the output value of the last card 10 connected in cascade. This will be described below with reference to FIG.

FIG. 2 is a diagram for explaining a card connection number detection method, and shows an example of a correspondence table created in accordance with the "change rule" and stored in, for example, a storage area (not shown). FIG. 9A shows the case where the change rule is 1 addition.
(B) is an example of the case of 1 subtraction. It should be noted that FIG.
2 shows a case where the arbitration bus 15 has 2 bits as in the example shown in FIG.

The correspondence table shown in FIG. 2A is an example in which the output of the start value setting unit 2 is "0" and the change rule is "1". In this case, the last card 10 The output value (referred to as a terminal value) is the number of cards connected as it is. However, only when the maximum number of connectable cards has been connected, the terminal value returns to “0” (the same as the output value of the start value setting unit 2), so that the card corresponding to the terminal value “0” is used. The number of connections is '4'.

The correspondence table shown in FIG. 2B is an example when the output of the start value setting unit 2 is "0" and the change rule is 1 subtraction. By inputting the “termination value” to a terminal (not shown), a card connected to the common bus 1, or the like, processing according to the number of mounted cards (for example, equalization processing of internal data) is performed. Can be done.

Regardless of the change rule (whether addition or subtraction), when the maximum number of connectable cards has been connected, the end value is the same as the output value of the start value setting unit 2. Become. By utilizing this, a configuration may be added in which the output value of the start-end value setting unit 2 is compared with the end value, and when both match, the card is not connected any more (warning, etc.).

As described above, according to the card connection number detection method, the correspondence table is created / stored based on the initial value and the "change rule", so that it is not necessary to add new hardware. , The number of cards connected in cascade.

The output value of the start value setting unit 2, that is, the start value is not limited to “0”, and the “change rule” is not limited to “1 addition” or “1 subtraction”. 2
The correspondence tables shown in (a) and (b) are merely examples, and the contents of the correspondence tables are set according to the starting value and the “change rule”.

FIGS. 3 and 4 are diagrams (parts 1 and 2) for explaining the method of determining the priority of using the bus. 3 and 4
The configuration of each of the cards 20A to 20D is substantially the same as that of the card 10 in FIG. 1 except that the configuration is such that the bus in-use signal 5 is output from each card 20 to the start value setting unit 4. Although the configuration for outputting the bus busy signal 5 is not particularly shown, any configuration may be used as long as the start value setting unit 4 can recognize that any one of the cards 20 is using the common bus 1. For example, a configuration using a multi-input / one-output OR gate for inputting the outputs of all the cards may be used.

The start-end value setting unit 4 is provided for each of the cards 20A to 20A.
When none of D uses the common bus 1, the output value is periodically changed sequentially. For example, 0 → 3 →
By subtracting “1” in a predetermined cycle such as 2 → 1 → 0 → 3, the starting end value is changed cyclically. still,
The change rule of the starting end value is not limited to “1 subtraction”, and may be, for example, “1 addition”. And one of the cards 20
When the bus busy signal 5 is turned on, the changing operation of the starting value is temporarily stopped. Then, when the bus busy signal 5 is turned off, the starting value is cyclically changed again until the next bus busy signal 5 is turned on.

On the other hand, each of the cards 20A to 20D
The output value from the preceding card (or the starting value setting unit 4) is transmitted to the ID via the input connector 23 and the arbitration bus 25.
It is temporarily stored in the storage unit 21. Each time the start value is changed by the start value setting unit 4, a new input value is set to I
The data is stored / updated in the D storage unit 21.

Here, a value indicating "the right to use the common bus" is set in advance, and this value is assumed to be "0" in FIG. When the value stored in its own ID storage unit 21 is “0”, each of the cards 20A to 20D recognizes that the right to use the common bus has been transferred to itself.
When a bus use request is issued while the user has the right to use the common bus, the start value setting unit 4 is informed that the common bus is being used by turning on the bus busy signal 5.

For example, in the example shown in FIG.
Since the "common bus use right" has been passed to the card 20A, the card 20A can use the common bus 1 if a bus use request has occurred in the card 20A at this time. When there is no bus use request in the card 20A, the "common bus use right" is transferred to the card 20B by changing the output of the start value setting unit 4 from 0 to 3 as shown in FIG.

The value indicating "the right to use the common bus" is not limited to "0". According to the above-described bus usage right priority determination method of the present embodiment, the circuit configuration is not complicated as in the conventional MULTIBUS II method, and the bus usage right priority determination is performed outside the conventional card. The method does not require an arbitration signal line twice as many as the number of cards to be connected.

Next, an example in which the bus use right is preferentially assigned to a specific card having a function to cope with the abnormality, for example, when an abnormality occurs, according to the bus use right priority determination method of the present embodiment will be described.

FIGS. 5 and 6 are diagrams (Nos. 1 and 2) for explaining a process performed when a parity error occurs in the common bus. Here, it is assumed that the specific card on which the corresponding process is performed is the card 30A.

In the system shown in FIGS. 5 and 6, the internal structure of each of the cards 30A to 30D is the same as that of the card 20 shown in FIGS.
The configuration is substantially the same as 3 and 4, the start value setting unit 41 periodically changes its output (start value) and temporarily stops the change of the start value when the bus busy signal 5 is turned on. Is substantially the same as

In the systems shown in FIGS. 5 and 6, the start value setting unit 41 temporarily saves the start value output at a certain point in time (hereinafter, the processing including the start value setting unit 41 and the stack 42). (The unit is referred to as a starting end value temporary setting unit 40)
And an abnormality notifying unit 50 for detecting that a parity error has occurred in the common bus 1 and notifying the starting end value temporary setting unit 40 of the error.

The processing operation when a parity error occurs in the common bus 1 will be described below with reference to FIGS. First, as shown in FIG. 5, the "right to use the common bus" is owned by the card 30C (starting value = 2).
It is assumed that the card 30C is using the common bus 1. It is assumed that a parity error has occurred in the common bus 1 in this state.

Upon detecting a parity error, the error notification unit 50 notifies the start value temporary setting unit 40 of "error occurrence". In response to the notification, the starting end value temporary setting unit 40 sets the preset value when the bus busy signal 5 is turned off, that is, the preset value such that the bus use right is passed to a specific card that performs the corresponding processing. (In this example, since the corresponding process is performed by the card 30A, the value “0”) is written in the starting value setting unit 41, and the starting value “2” at that time is saved in the stack.

As a result, the state shown in FIG. 6 is reached, and the card 30A obtains the right to use the bus. The card 30A is a card having a dedicated processing function for performing, for example, a process when a parity error occurs, and a bus use request is generated when the parity error occurs. From this, card 30A
When the bus usage right is obtained, the bus in-use signal 5 is turned on, and the above-described processing when a parity error occurs is executed.

When the card 30A completes the processing for dealing with the parity error and turns off the bus busy signal 5, the starting end value temporary setting unit 40 stores the value '2' saved in the stack 42. The start right value setting unit 41 is returned to return the right to use the bus to the card 30C.

In the above-described embodiment, the right to use the bus is returned to the card 30C after the processing for dealing with the parity error is completed. However, the present invention is not limited to this. For example, the right to use the bus may be transferred to the next card 30D. It may be.

In the example shown in FIGS. 1 to 6, each card 1
0, 20, and 30 store an input value from a preceding card or the like (for example, store as an own ID) and output a value obtained by changing the input value according to a predetermined change rule to a subsequent card. However, the present invention is not limited to this. For example, a configuration may be employed in which a value obtained by changing an input value from a preceding card or the like according to a predetermined change rule is stored (as its own ID) and output to a subsequent card. Good.

[0056]

As described above in detail, according to the ID assignment method of the present invention, in the system configuration system using a cascade connection card, which is a system in which the system can be miniaturized (not limited by the size of the baseboard). It is not necessary to manually set an ID, and the ID is automatically assigned to each card. As a result, it is possible to perform ID assignment without any trouble and no mistake.

Further, for example, by storing a table or the like indicating the correspondence between the terminal value and the number of connected cards based on the initial value and the change rule, in the above-mentioned ID assignment method, By detecting the output value, the number of connected cards can be automatically determined.

Further, according to the bus use right priority determination method of the present invention, the bus use right can be fairly distributed to each card with a simple circuit structure without complicating the circuit structure. Further, the number of cards represented by a power of 2 of the number of arbitration buses can be connected without requiring an arbitration signal line twice as many as the number of cards to be connected.

Further, for example, when an abnormality is detected, a right to use the common bus can be temporarily given to a specific card dealing with the abnormality. Thus, for example, a system in which privileged processing is performed on a specific card and execution of a normal application is assigned to another card can be constructed.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an ID assignment method.

FIG. 2 is a diagram for explaining a card connection number detection method.

FIG. 3 is a diagram (part 1) for explaining a bus use right priority determination method;

FIG. 4 is a diagram (part 2) for describing a bus use right priority determination method;

FIG. 5 is a diagram (part 1) for describing a process performed when a parity error occurs in the common bus.

FIG. 6 is a diagram (part 2) for describing a process performed when a parity error occurs in the common bus.

FIG. 7 is a diagram showing an example of a configuration using a conventional base board.

FIG. 8 is a diagram showing an example of configuring a common bus using a conventional cascade connection card.

FIG. 9 is a diagram for explaining a conventional method of making a bus use right priority determination outside a card.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Common bus 2 Start value setting part 3 Arbitration bus 4 Starting value setting part 5 Bus busy signal 10A-10D card 11 ID storage part 12 Adder 13 Input connector 14 Output connector 15 Arbitration bus 16 Internal bus 17 Connector 18 Connector 20A-20D Card 21 ID Storage Unit 22 Adder 23 Input Connector 24 Output Connector 25 Arbitration Bus 26 Internal Bus 27 Connector 28 Connector 30A-30D Card 31 ID Storage Unit 32 Adder 33 Input Connector 34 Output Connector 35 Arbitration Bus 36 Internal bus 37 Connector 38 Connector 40 Starting value temporary setting unit 41 Starting value setting unit 42 Stack

Claims (6)

[Claims] 1. A system in which a plurality of cards are cascaded to form a common bus in each system, an input value input from a preceding card is changed according to a predetermined change rule, and a value after the change is changed to a subsequent step. A cascade connection card, comprising: a change unit that outputs the input value or a value changed by the change unit as its own ID. 2. An ID assigning method in a system in which a plurality of cards are cascaded to form a common bus, wherein a predetermined initial value is input to a cascaded front-end card. And storing the changed value obtained by changing the input initial value in accordance with a predetermined change rule or the initial value as its own ID, and outputting the changed value to a subsequent card to reach the last card. Up to each card,
By storing the value obtained by changing the value input from the preceding card in accordance with the predetermined change rule or the input value as its own ID and outputting the changed value to the subsequent card, the cascade connection is established. An ID assignment method for assigning an ID to each card. 3. The ID according to claim 2, wherein the number of cards in the cascade connection is detected based on an output value of the last card, the initial value, and a predetermined change rule. Assignment method. 4. A bus usage right priority determination method for a common bus in a system in which a plurality of cards are cascaded to form a common bus, wherein the bus usage right arbitration control means controls the first card in a cascade connection. The value held by each card is sequentially changed by changing the initial value to be input to at a predetermined cycle according to a predetermined rule, and the cascade connection card holding a predetermined value is A bus use right priority determination method for a common bus. 5. When the card having the right to use the common bus uses the common bus, the card notifies the bus use right arbitration control means that the card is using the common bus. 5. The method according to claim 4, wherein the right-of-use arbitration control unit stops changing the initial value during the notification. 6. The bus use right arbitration control means changes an initial value such that, when a specific event occurs, a bus having a common bus is transferred to a card having a function dedicated to the specific event. 5. The method according to claim 4, wherein the priority is determined.