JPH0363750A - Interface unit used for multidrop access system - Google Patents

Abstract

PURPOSE:To output accesses from a main bus at the same timing by using one kind of an interface unit by automatically switching it to a master unit and a slave unit. CONSTITUTION:A first interface part 10 for main bus side connection, timing part 13 to control the access timing between buses, master/slave (M/S) decision part 15, second interface part 12 for master bus or slave bus side connection, second timing part 14 and selector part 16 to select a connection source corresponding to the result of the M/S decision part 15 are provided. An interface part 11 is provided with the switching function of connection corresponding to the result of the M/S decision part 15 for multidrop bus side connection. According to the decided result of the M/S decision part 15, the master unit or slave unit is automatically set and the accesses to the master bus and slave bus are outputted at the same timing by the first and second timing parts 13 and 14. Thus, the access can be outputted from the main bus to the master bus and slave bus at the same timing.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Figures 4 and 5) Means for solving the problem to be solved by the invention (Figure 1) Working examples (Figures 2 and 3) Effects of the invention [Summary] Regarding the interface unit used in the multi-drop access method, one type of interface unit can automatically switch between a master unit and a slave unit depending on the connection method, and can be connected to the main bus. The purpose of this is to output accesses to the master bus and slave buses at the same timing, and includes a first interface section for connecting to the main bus side, a tying section that controls access timing between the buses,
A master/slave (M/s) determination section, a second interface section for connection on the master bus or slave bus side, a second timing section, and a connection source selected according to the results of the M/S determination section. It consists of a selector section and an interface section that has a connection switching function according to the result of the M/S judgment section for connection on the multi-drop bus side. is automatically set, and the first and second
The timing unit is configured to output access to the master bus and slave bus at the same timing.

[Industrial application field]

The present invention relates to an interface unit used in a multi-drop access system, and more specifically, the present invention relates to an interface unit used in a multi-drop access system, and more specifically, it is used to connect multiple buses in a system with multiple multipaths. This invention relates to an interface unit used in a multi-drop access system that can be used in common by automatic switching between a master unit and a slave unit.

[Conventional technology]

As computer systems have become faster in recent years, there has been a demand for smaller units connected on the same bus.

Therefore, only the units that are constantly accessed are connected to the main bus, and the other units are connected to the sub-bus.

Therefore, an interface unit between the main bus and the sub-bus is required.

FIG. 4 is a system block diagram of the conventional multi-drop access method, where 1 is the CPU, 2 is the main bus, and 3 is the main bus.
is the master bus, 4 is the multidrop bus, 5-1.5-
2 is the slave bus, 6 is the master unit, 7-1.7-
2 indicates a slave unit.

In the multi-drop access method, as an IF unit (interface unit) for connecting multiple buses, there is a master unit 6 which is an IF unit with the main bus 2, and a JF unit with the bus connected to that unit.
A slave unit 7-1, 7-2- is required.

Master unit 6 and slave unit Fu 1.7-2-
This uses a unit with a different structure, and these two types of interface units were used.

In addition, when accessing multiple slaves from the master unit 6, the access timing of the master bus 3,
The slave buses 5-1 and 5-2 can be accessed at the same timing.

FIG. 5 is an explanatory diagram of a conventional interface unit, and the same reference numerals as in FIG. 4 indicate the same parts.

(The main bus side, the master bus side,
The interface section TF is provided on each of the multi-drop side and the multi-drop side, and two timing sections TM are provided.

The slave unit 7-1 has a multi-drop bus side,
The structure is such that an interface section JF is provided on each side of the slave bus, and one timing section TM is provided.

In this way, the master unit 6 and slave unit 7-
1 (slave units 7-2 and 7-3 also have the same structure).

[Problem to be solved by the invention]

In the conventional device as described above, the master unit and slave unit have different structures and cannot be used in common, so there is a drawback that two types of interface units must be developed.

The present invention eliminates these conventional drawbacks and automatically switches the connection method between master and slave units using one type of interface unit, allowing access from the main bus to be accessed simultaneously to the master and slave buses. The purpose is to enable timely output.

[Means to solve the problem]

FIG. 1 is a diagram showing the principle of the present invention, and the present invention will be explained in detail below based on this diagram.

The present invention provides an interface unit used in a multidrop system that controls the mutual access timing of a multidrop bus connected to a main bus, a master bus, and a slave bus connected to a multidrop bus, and connects the buses. A first interface unit 10 for main bus side connection, a timing unit 13 that controls access timing between buses, and a master/slave (M/S) that determines whether the connection destination is a master bus or a slave bus.
a determination unit 15, a second interface unit 12 for connection on the master bus or slave bus side, a second timing unit 14, and a selector unit I6 that selects a connection source according to the result of the M/S determination unit 15; , an interface section 11 having a connection switching function according to the result of the M/S determination section 15 for connection on the multi-drop bus side;
The master unit or the slave unit is automatically set based on the determination result of the /S determination unit 15, and the first and second timing units 13.14 output accesses to the master bus and slave bus at the same timing. It is characterized by being adjusted to.

The M/S determination unit 15 determines that the unit is a master unit if there is a connection from the main bus, and determines that it is a slave unit if there is no connection from the main bus, and controls the selector unit 16 and the interface (1) on the multi-drop bus side, and the timing unit 14, Adjust the accesses to the master bus and slave bus so that they are output at the same timing.

Now, when the M/S determining section 15 determines that the interface section 10 has been connected from the main bus, it switches and controls the selector section 16 and the interface section 11 so that it becomes the master unit.

As a result, the selector unit I6 selects the output from the timing unit 13 and accesses the master bus side via the timing unit 14 and the interface unit 12, and the output from the timing unit 13 accesses the multidrop bus side. can be switched to

Furthermore, if there is no connection from the main bus, the M/S determining section 15 determines this and controls switching of the selector section 16 and the interface section 11 so that they become slave units.

In this case, the selector section 16
The output from the slave bus is accessed via the timing section 14 and the interface section 12 at the same timing as the master unit, and the interface section 11 selects the output from the slave bus side to the multidrop bus side. Connecting.

[Effect]

Since the present invention is configured as described above, the master unit and slave unit are automatically switched by simply connecting the interface unit, and the output to the bus is timed in the timing section, so the master bus and the slave unit are automatically switched. Slave buses can be accessed at the same timing.

Therefore, one type of interface unit can be used in common as a master unit and a slave unit, so there is no need to develop two types of interface units as in the past.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 2 is a configuration diagram of one embodiment of the present invention, and 10.1
1.12 is an interface section, I3 and I4 are timing sections, 15 is an M/S (master/slave) judgment section, 1
6 indicates a selector section.

In addition, 17, I8 are buffers, 19.20 are AND (logical product) gates, 21.22 are OR (logical sum) gates, 2
3 represents an inverter, and 24 represents a pull-up resistor.

The illustrated interface unit includes an interface section 10, a timing section 13, an OR gate 22, and an M/S determination section 15 on the main bus side, and an interface section 12, a timing section 14, and a selector on the master bus or slave bus side. A section 16 is provided, and an interface section 11 is further provided on the multidrop bus side.

If the M/S determination unit I5 is connected to the main bus, the input becomes low level "L", and if it is not connected, the input becomes oven.

Therefore, if the input is "L", "L" is output to the A line, and a high level rH signal inverted by the inverter 23 is output to B,%9, which connects the selector section 16 and interface section 11. Control and automatically set on the master unit.

When the input to the M/S determination unit 15 is an oven, the A line is pulled to rH by a pull-up resistor connected to a high-level power supply.
”, the B line becomes “L”, and this signal controls the selector section 16 and the interface section 11 to automatically set it as a slave unit.

The automatic switching setting between the master unit and slave unit as described above is performed as follows.

(b) In the case of the master unit, the A line is rLJ and the B line is rH, so the selector section 1
6, antgame 120 is opened, and andgate 19
When the buffer 17 is closed, the buffer 17 becomes in use and the buffer 18 becomes unused in the interface section 11.

Therefore, signals from the main bus side are output to the multi-drop bus in the order of interface section 10 → timing section 13 → buffer 17, and also output from interface section 10 → timing section 13 → AND gate 20 → timing section 14 → interface section 10 → timing section 13 → buffer 17. It passes through the face section 12 and is output to the master bus.

The signal from the multidrop bus is routed through the buffer 17 → OR gate 22 → timing section 13 → interface section 10.
The signals from the master bus side are output to the main bus in the following order: interface section 12 → timing section 14 → OR gate 22 → timing section 13 → interface section 10.

(b) In the case of a slave unit, the A line is rHJ and the B line is "L", so the selector section 1
At 6, the AND gate 119 is opened and the AND gate 20 is closed, and in the interface section 11, the buffer 18 is in the used state and the buffer 17 is in the unused state.

This allows the multidrop bus and slave bus to be connected and accessed.

FIG. 3 is a diagram showing an example of use of the interface unit according to the present invention, and the same reference numerals as in FIGS. 2 and 4 indicate the same parts.

The illustrated master unit 6 and slave unit 7-1 are
The interface unit according to the present invention is used as a master unit and a slave unit, respectively, and the internal structure is the same.

The master unit 6 is connected to the main bus, which is determined by the M/S determining section 15 and controls the selector 16 and the interface section 11 .

As a result, the main bus 2, master bus 3, and multidrop bus 4 are connected and accessible, and the timing unit 14 allows the master bus and slave bus to be accessed at the same timing.

Furthermore, since the slave unit 7-1 is not connected to the main bus, the input to the M/S determination section 15 is an oven.

In this state, the selector section 16 and the interface section 11
, and connects the multidrop bus 4 and slave bus 5-1 to enable access.

In this way, t! The 1ffl interface unit can be automatically switched and used as a master unit and a slave unit, and in this case, the master bus and slave bus can be accessed at the same timing.

〔Effect of the invention〕

As explained above, the present invention has the following effects.

(1) One type of interface unit can be used by automatically switching between a master unit and a slave unit, so there is no need to develop two types of interface units as in the past for use in multi-drop access methods. .

(2) Automatic switching between master unit and slave unit eliminates setting errors.

(3) Access from the main bus can be output to the master bus and slave bus at the same timing.

[Brief explanation of drawings]

Figure 1 shows the principle of an interface unit used in the multi-drop access system according to the present invention, Figure 2 shows the constituent countries of an embodiment of the present invention, and Figure 3 shows an example of how the interface unit according to the present invention is used. 4 is a system block diagram of a conventional example, and FIG. 5 is an explanatory diagram of an interface unit of a conventional example. 101II, 12 - Interface section 13.14 - Timing section 15 - M/S judgment section 16 - Selector interface unit Example of use of 7Aids Uni, 7T System block diagram of conventional example Figure 4

Claims (1)

[Claims] In an interface unit used in a multidrop method for connecting buses by controlling the mutual access timing of a multidrop bus connected to a main bus, a master bus, and a slave bus connected to the multidrop bus, and the first interface section (10
), a timing unit (13) that controls access timing between buses, and a master/slave (M/S) determination unit (15) that determines whether the connection destination is a master bus or a slave bus.
, a second interface section (12) for connection on the master bus or slave bus side, and a second timing section (14)
a selector unit (16) that selects a connection source according to the result of the M/S determination unit (15); and a selector unit (16) that selects a connection source according to the result of the M/S determination unit (15);
), which automatically sets the master unit or slave unit based on the determination result of the M/S determination section (15), and and an interface unit used in a multi-drop system, characterized in that second timing sections (13, 14) adjust access to the master bus and slave bus so that they are output at the same timing.