JPH02135560A - Address allocating method - Google Patents

Abstract

PURPOSE:To automatically allocate addresses to respective slave cards by making access to the respective slave cards with a master card in a daisy-chain system, and writing the addresses corresponding to ID data from the slave cards to the slave cards. CONSTITUTION:A master card 1 an slave cards 21 to 2n are alternately connected by a data bus 3, an address bus 4, a daisy-chain signal line 5, and a signal line 6 of read/write signal (R/W signal). The priority of the slave cards is in the sequence from 21 to 2n. A daisy circuit 21 provides a daisy-chain signal and the R/W signal, when the self-card does not respond, the daisy-chain signal is sent to a low-order slave card by opening a gate 22, when it responds, the sending of the ID data indicating the type of the self-card and the writing of the address corresponding to the ID card are executed by time-sharing. Thus, the addresses can be automatically allocated to the respective slave cards.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a method of assigning an address to each slave card in a system in which a plurality of slave cards are connected to one master card.

<Prior Art> In a system in which a plurality of slave cards are connected to one master card, each slave card has an address, and the master card communicates with the slave cards by accessing each address. Therefore, it is necessary to assign an address to each 'slave card.

Creating different hardware for each address in order to allocate addresses increases costs. For this reason, in the past, a DIR switch with a common configuration was formed on each slave card, and the user assigned addresses by changing the setting state of the DIR switch for each slave card.

<Problem to be solved by the invention> However, with this method, when the user performs setting operations, the user may accidentally assign the same address twice, or the DI
There was a problem in that the housing and board had to be designed so that the user could operate the R switch.

Another problem is that the user often damages the board of the slave card when performing setting work. Furthermore, there is a problem in that setting work is troublesome when there are a large number of cards.

For this reason, there has been a desire for a method that can easily allocate addresses without tampering with slave cards.

The present invention has been made in response to such demands, and an object of the present invention is to realize a method of automatically assigning an address to each slave card by allowing a master card to access the slave cards in a daisy chain manner.

Means for Solving the Problems The present invention provides a system in which a plurality of slave cards are connected to one master card, and the master card communicates with the slave card by accessing the address of one of the slave cards. , the master card uses a daisy chain signal to access each slave card in a daisy chain manner, receives ID data indicating the type of card from the slave card that responded to the access, and sends an address corresponding to this ID data. This is an address assignment method in which address assignment to the slave card is completed when writing is written to the slave card and the daisy chain signal is returned to the master card or when the slave card no longer returns an acknowledge signal in response to the daisy chain signal.

In the present invention, the master card accesses the slave cards in a daisy chain manner, assigns addresses to the slave cards upon access, and ends address assignment when all slave cards have been accessed. do.

<Example> Hereinafter, the present invention will be explained using the drawings.

FIG. 1 is a diagram showing an example of the configuration of a system for implementing the present invention.

In the figure, 1 is a master card, and 21 to 2TL are slave cards. These cards are interconnected by a data bus 3, an address bus 4, a daisy chain signal line 5, and a read/write signal (hereinafter referred to as R/W signal) signal line 6.

The slave cards have higher priority in the order of 21.2□...21. 2. Slave card configuration.
will be explained using an example.

Slave card 2. Then, 21 receives the daisy chain signal and the R/W signal, and if the own card does not respond, it opens the gate 22 and sends the daisy chain signal to the lower slave card, and if it responds, it indicates the type of the own card. This is a daisy circuit that time-divisionally transmits the ID data shown and writes the address corresponding to the ID data. 2
3 is a storage means in which ID data is stored; 24 is a gate that is opened by the signal ID from the daisy circuit 21 when transmitting ID data; and 25 is a gate that is opened by a latch signal ADD when writing an address corresponding to the ID data. This is a latch for storing.

These components 21 to 2 are also included in other cards 22 to 2π.
5 is provided at least.

Next, the operation of such a device will be explained.

FIG. 2 is a time chart of signals used in the system of FIG. In this time chart, DCI and DC2 are digital signal signals applied to slave cards 21 and 2□, respectively.

Also, the daisy chain signal is high and active.

First, the master card 1 sets the daisy chain signal DCI to a high level to notify the slave card 2 that it is accessing for address assignment. Also,
The R/W signal is set to high level to notify that it is a read cycle.

This is the timing shown in a.

Next, slave card 2. opens the gate 24 at the timing when the signal ID becomes low level, and sends the ID signal to the data bus 3.
Output data. Master card 1 reads this ID data. This is the timing shown in b.

After reading, the master card 1 sets the R/W signal to low level to indicate entering a write cycle, and the slave card 21 releases the data bus 3. This is C
The timing is shown in .

Thereafter, the master card 1 outputs an address corresponding to the read II) data to the data bus 3.

This is the timing shown in d.

Next, slave card 2. stores the address of the data bus 3 in the latch 25 using the latch signal ADD, and makes it the address of its own card. This is the timing shown in e.

After that, slave card 2. After confirming that all address assignment operations have been completed, the gate signal GA is
Set TE to high level. This is the timing shown in f.

When the gate signal GATE is at a high level and the daisy chain signal DCI is at a high level, the daisy chain signal DC2 is at a high level.

This is the timing shown in g.

When the slave card 22 confirms that the daisy chain signal DC2 is at a high level, it repeats the operations at the timings a to f described above.

Thereafter, similar operations are performed on each slave card, and when the master card 1 confirms that the signal output from the gate 22 of the last slave card 2π has become high level, it completes address assignment for all slave cards.

In addition, in the embodiment, when the daisy chain signal returns to the master card, it is known that access to all cards has been completed, but the completion of access can also be detected by other methods. Good 0 For example, each slave card is equipped with a function that returns an acknowledge signal to the master card when it is accessed, and the master card does not send an acknowledge signal to all cards when accessing by daisy chain. It may be determined that the access has ended.

Effects> According to the present invention, the master card is allowed to access the slave card in a daisy chain manner, and an address is assigned to the slave card at the time of access. From this, the following effects can be obtained.

■Since the user does not have to fiddle with each master card to set the address, there is no need to damage the card board.

■No more mistakes in assigning the same address twice.

■There is no need to configure the system so that the user can set the DIR switch.

■Addresses can be automatically assigned.

■Addresses can be easily assigned even if there are many cards.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the configuration of an apparatus for carrying out the method according to the present invention, and FIG. 2 is an explanatory diagram of the operation of the apparatus shown in FIG. 1. DESCRIPTION OF SYMBOLS 1... Master card, 21-21... Slave card, 21... Daisy circuit, 22.24... Gate, 23... Storage means, 25... Latch, 3... Data bus , 4... Address bus, 5.6... Control signal line.

Claims (1)

[Claims] In a system in which a plurality of slave cards are connected to one master card, and the master card communicates with the slave cards by accessing the address of any of the slave cards, the master card comprises: Each slave card is accessed in a daisy chain manner using a daisy chain signal, ID data indicating the type of card is received from the slave card that responded to the access, and an address corresponding to this ID data is written to the slave card. An address assignment method that ends address assignment to a slave card when the daisy chain signal returns to the master card or when the slave card no longer returns an acknowledge signal in response to the daisy chain signal.