JPH01284952A - Device address setting system - Google Patents

Abstract

PURPOSE:To avoid the setting errors of device addresses by enabling the peripheral devices connected to a common bus to automatically set their own addresses respectively. CONSTITUTION:A host computer performs the input/output of data to its corresponding peripheral device via a device controller DCTR24. Then it is decided whether the peripheral device having its address equal to the address shown by a counter i31 of a RAM 242 storing the identification number, etc., of the peripheral device is connected to a bus 25 or not. If so, the busy and ready signals are returned from said device. Thus the counter i31 is counted up. In case the peripheral device is not connected to the bus 25 with the counter value larger than the number of peripheral devices, the present value of the counter i31 is used as the identification number of the corresponding peripheral device and stored in an identification number area IDNO32 of the RAM 242.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device address setting method for setting each device address of a plurality of peripheral devices connected to a common system bus.

[Prior Art] Conventionally, a plurality of peripheral devices connected to a common system bus are provided with address designation switches such as date switches or jumper wires to specify their addresses. The designers or users of these systems set the addresses of each peripheral device by setting these addressing switches to different address values to identify each device. .

[Problem to be solved by the invention] However, in the above conventional example, when a new device is added to the system bus or an attempt is made to change the address of each peripheral device, each device already connected to the system bus It is necessary to determine the address of the device to be added so that it does not overlap with the address of the device. Furthermore, when a user wants to change the address of a device, he or she must check the addresses of all connected devices before changing the address, which is extremely troublesome. Furthermore, since such address settings are all performed manually, there is a problem that duplicate addresses may be set and the system may not operate.

The present invention has been made in view of the above conventional example, and an object of the present invention is to provide a device address setting method that allows each peripheral device connected to a common bus to automatically set its own device address.

[Means for Solving the Problems] In order to achieve the above object, the device address setting method of the present invention has the following configuration. That is, the device address setting method sets the address of each of a plurality of peripheral devices connected to a common bus, and each of the peripheral devices outputs an output such as device address data specifying the peripheral device to the bus. means for determining whether a peripheral device having the device address data exists based on a response signal returned from the peripheral device in response to the device address data; and determining the device address by the determining device. and means for storing the device address data as the device address of the device itself when it is determined that the peripheral device does not exist.

[Operation] In the above configuration, each of the plurality of peripheral devices connected to a common bus outputs device address data that identifies the peripheral device to that bus, and returns data from the peripheral device in accordance with the device address data. Based on the response signal received, it is determined whether there is a peripheral device having the device address data. In this way, when it is determined that there is no peripheral device having that device address, the device operates to store the device address data as its own device address.

[Embodiments] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Explanation of the configuration of the system bus and its peripheral devices (Figs. 1 to 2)] Fig. 2 shows the SCSI (Small Com
1 is a diagram showing a schematic configuration of a putterSystem Interface bus.

In the figure, 20 is a host computer of the SCSI bus 25, and is connected to the bus 25 via a host adapter 20-1. 24-1 to 24-3 are printers 21, respectively.
A device controller (
DCTR).

Figure 1 shows the device controller (DCTR) of the embodiment.
24 is a block diagram showing a schematic configuration of 24.

Here, 240 is an MPU such as a microprocessor, and R
It outputs various control signals according to the control program stored in the OM 241 to execute interface control between the SC3I bus 25 and peripheral devices such as disks. A RAM 242 is used as a work area for the MPU 24o, and also stores identification numbers of corresponding peripheral devices as will be described later. 243 is SC3I bus 2
This is an SCS I bus protocol driver/receiver (SPDR) that controls the connection with 5. 244 is an I10 interface unit that controls the interface between the device controller (DCTR) and peripheral equipment.

With the above configuration, the host computer 20
It is possible to input and output data to and from a corresponding peripheral device via the printer 24, for example, outputting data to the printer 21 for printing, storing data on the disk 22, or data stored on the disk 22. can be read.

[Description of device address determination processing] FIG. 3 is a flowchart showing the determination processing of the device address of a peripheral device by the device controller (DCTR) of the embodiment, and the control program that executes this processing is R.
It is stored in OM241. This processing program is
For example, the process may be started by power input to the device, or a switch for instructing address setting may be provided in the DCTR 24, and the process may be started by pressing the switch.

When this process is started, the counter i31 of the RAM 242 is set to "0" in step s1, and it is checked in step S2 whether or not i31 is greater than "7". This is because the maximum number of peripheral devices connected to the SC3I bus is eight. If it is “7” or less, the process advances to step S3 and the counter i
31 is output to the 5C3I bus 25, and the peripheral device having the device address equal to i is identified as the 5C3I bus 25.
Check whether it is connected to 3I bus 25.

If a peripheral device with a device address equal to the address indicated by counter i31 is connected to this bus 25, signals such as g and ready will be sent back from that device, so such signals will not be sent back. It is determined whether a peripheral device having that address is connected to the bus 25. If a device with that address is connected, the process advances to step S5, and the RAM
The counter i31 of 242 is incremented by 1 and the process returns to step S2.

If the value of the counter i31 is "7" or more in step S2, the process proceeds to step S6, where an error is displayed as there is no vacant device address, and the process ends. This error display may be notified by lighting an LED or the like, or may be displayed on a display unit such as a CRT (not shown) of the host computer 2°.

In step S4, the peripheral device equal to the value of i is this SC3I.
If it is not connected to the bus 25, proceed to step S7;
The current value of counter i31 is stored in the identification number area (IDNO) of RAM 242 as the identification number of the corresponding peripheral device.
32. That is, for example, this process is
-1, it is stored in the ID NO 32 of the DCTR 24-1 as the device address of the printer 21. Once the device address of the peripheral device is determined in this way, the process advances to step S8, and data input/output is performed via the 5CSI bus 25 based on SCSI protocol control.

Although this embodiment has been described in the case of an SC3I bus, the present invention is not limited to this and can be applied to interface circuits of other systems.

Additionally, if the device addresses of multiple peripheral devices connected to the bus are not set at all, the addresses will be determined in order from the side device that first executed the process shown in Figure 3. Become.

Furthermore, by configuring the RAM area that stores the identification number (IDNO) to be non-volatile, it is possible to omit address setting processing every time the power is turned on.

As explained above, according to this embodiment, the device address of each peripheral device is automatically determined, so the address of each device can be reset due to a manual device address setting error or a change in the device address. This has the effect of omitting troublesome processing such as.

[Effects of the Invention] As explained above, according to the present invention, each peripheral device connected to a common path can automatically set its own device address, so it is possible to prevent device address setting errors and This has the effect of saving time and effort for address setting.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the schematic configuration of the device controller DCTR of the embodiment, FIG. 2 is a block diagram showing the schematic system configuration connected to the SCSI bus of the embodiment, and FIG. 3 is a block diagram showing the schematic configuration of the device controller DCTR of the embodiment. 3 is a flowchart illustrating identification number determination processing performed by a device controller. In the figure, 20... host computer, 21... printer, 22... hard disk, 23... floppy disk, 24... device controller, 25...
...SC3I bus, 31...Counter i, 32...
Identification number area (IDNO), 240...MPU,
241...ROM, 242...RAM, 243...
-5PDR1244...I10 interface unit. Patent applicant Canon Co., Ltd. L10 mark/3N Figure 1

Claims (1)

[Claims] A device address setting method for setting addresses for each of a plurality of peripheral devices connected to a common bus, wherein each of the peripheral devices has device address data specifying the peripheral device on the bus. an output means for outputting the device address data; a determination means for determining whether or not a peripheral device having the device address data exists based on a response signal returned from the peripheral device in response to the device address data; A device address setting method comprising: means for storing device address data as a device address of the device itself when it is determined that a peripheral device having the device address does not exist.