JPH0514345A - Daisy chain connection revision method - Google Patents

Abstract

(57) [Summary] [Purpose] The termination setting operation is not required when adding or relocating daisy-chained devices. [Structure] A terminal resistor 112 is provided in the device D1 in the basic subsystem 2, and the connectors provided in the cables 10 and 14 in the sub devices 2, 3a to 3k without changing the connection of the device D1 from the lowest order. An additional device is newly connected or relocated to (not shown). Further, the expansion subsystems 3a to 3k are expanded by the external connection terminals 5a and 5b and the input terminals 6a and 6b.
It is only necessary to connect b as shown in FIG. At the time of expansion or relocation, the lowest device D1 in the basic subsystem 2 having the terminating resistor remains unchanged, so that termination setting is unnecessary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a daisy chain connection changing method, and more particularly to a daisy chain (DASIYCHA) like an external storage device of a computer.
In a system in which multiple devices are connected in a daisy chain via an (IN) type interface, when adding or relocating devices, it is preferable to change the daisy chain connection to eliminate the need for termination setting operation in the devices. Regarding the method.

[0002]

2. Description of the Related Art In the prior art, when a plurality of devices are connected in a daisy chain via a daisy chain type interface, a termination setting operation is required. Here, the daisy chain connection means a connection method in which a plurality of devices are vertically connected (annular chain connection) to the host device in one column. In a plurality of devices connected in a daisy chain, the device to be added or relocated is the last device in the chain.

When adding a device, it is necessary to first set termination for the additional device and then for the final device before the addition. Here, the termination setting means that a terminating resistor is installed in the device for the additional device, and that the terminating resistor is removed for the final stage device before the additional device.

Further, when a device is relocated, the termination setting is performed for the final stage device of the relocation source (relocation device) and the device immediately before the final stage, and the termination setting is also set for the final stage device of the relocation destination. Need to do. Here, the termination setting means that a terminating resistor is newly installed in the transfer device and the device immediately before the final stage, and the terminating resistor is removed from the final stage device of the transfer destination. Means to do.

As prior arts related to the above-mentioned prior art, Japanese Patent Laid-Open Nos. 63-124643 and 63 are known.
There is the invention disclosed in Japanese Patent Publication No. 164649.

[0006]

In the above-mentioned prior art, when a daisy chain-connected device is added or relocated, a termination setting operation is required for the target device, which is very troublesome and a work error. There is a problem that it causes the occurrence.

The present invention has been made in view of the above-mentioned problems of the prior art, and when a device connected in a daisy chain is added or relocated, a daisy chain connection change of a device that does not require termination setting operation is performed. To provide a method.

[0008]

SUMMARY OF THE INVENTION A daisy chain connection changing method of the present invention comprises a controller for controlling a plurality of devices in response to a command from a host device, and a plurality of daisy chain connected to the controller. In a system including a device, a terminating resistor is installed in the lowest connected device among the above plurality of devices,
It is characterized in that another device connected in a daisy chain is added / relocated without changing the connection of the device in which the terminating resistor is installed from the lowest position.

[0009]

According to the present invention, the device provided with the terminating resistor is retained as the lowest device. Therefore,
When adding or relocating a new device to another device connected in a daisy chain, the termination setting operation in the device becomes unnecessary.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the embodiments shown in the accompanying drawings. FIG. 1 shows the first of the present invention.
It is a block diagram showing an example of. In FIG. 1, 1 is a higher-level device (host), 2 is a basic subsystem, and 3a to 3a.
k indicates an expansion subsystem. As shown, the basic subsystem 2 is composed of a control device 4, external connection terminals 5a and 5b, devices D1 and D2 to Dn, a daisy chain type interface cable 10 and an internal interface cable 14. The devices D1 and D2 to Dn are daisy chain connected by the daisy chain type interface cable 10 so that the device D1 serves as a terminating device.
1 is provided with a terminating resistor 12. The expansion subsystems 3a to 3k are, as shown, the basic subsystem 2
And the external connection terminals 5a and 5b, the input terminals 6a and 6b, and the device D, respectively.
1, D2 to Dn, a daisy chain type interface cable 10 and an internal interface cable 14. And the final expansion subsystem 3
The external connection terminals 5a and 5b of k are connected by a bypass cable 7.

In the above configuration, the daisy chain type interface cable 10 is a plurality of devices D.
This is an interface cable in which 1, D2 to Dn are vertically connected in series and terminal resistors are installed at both ends thereof in order to prevent a difference in signal level due to loss or the like in the cable. In this example, in addition to the termination resistor 12 provided in the device D1, the control device 4 is also provided with a termination resistor (not shown). Also, the internal interface cable 1
0 and daisy chain type interface cable 1
4 is provided with connectors (not shown) for the maximum number of devices that can be mounted in each subsystem 2, 3a to 3k. As such a connector, a card edge or socket type connector is used.

Next, in the embodiment shown in FIG. 1, the devices in the basic subsystem 2 and the expansion subsystems 3a to 3a.
The case of adding devices in k will be described. In this case, a new additional device may be connected to the above-mentioned connectors provided on the internal interface cable 10 and the daisy chain type interface cable 14 by the maximum number of devices that can be mounted in the sub device. .. At that time, since the termination device D1 in the basic subsystem 2 is unchanged and the termination resistor 12 is already provided in the device D1, the termination setting is unnecessary.

Further, in the embodiment shown in FIG. 1, the extension subsystem 3k is further added to the extension subsystem 3k.
The case of expanding the number will be described. In this case, the bypass cable 7 connected to the external connection terminals 5a and 5b of the expansion subsystem 3k is removed, and each external connection terminal 5a and 5b of the expansion subsystem 3k and the subsystem to be newly added (not shown). No.) each input terminal (6a, 6b) is connected, and a pair of external connection terminals (5a, 5) of the newly added subsystem
It is sufficient to connect b) with a bypass cable (7).

As is clear from the above description, the first
According to this embodiment, it is possible to easily add a device unit and a subsystem unit without setting termination.

Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment shown in FIG. 2 is an embodiment when the present invention is applied to an optical disk subsystem. In the second embodiment, as shown, the host device 10
1, an optical disc subsystem basic unit 104, and an optical disc subsystem expansion unit 105. The host device 101 and the optical disc subsystem basic unit 104 are
The optical disk subsystem basic unit 104 and the optical disk subsystem expansion unit 105 are connected via the SCSI interface cable 102, and the external expansion cable 1
It is connected via 18. The optical disk subsystem basic unit 104 includes a SCSI input / output connector 103, an optical disk formatter controller 106, an optical disk drive device (indicated by ODD in the figure) 112 and 113, and an ESD.
I-B cable 107 and external connector 109a, 1
09b. Here, the optical disc formatter controller 106 can control up to four optical disc drive devices. A terminal resistor 116 is installed in the optical disk drive device 112.
The optical disk subsystem expansion unit 105 includes input connectors 110a and 110b3, optical disk drive devices (indicated by ODD in the figure) 114 and 115, an ESDI-B cable 108, and external connection connectors 109a and 109b. Here, ESDI-B cable 10
Reference numerals 7 and 108 denote daisy chain type interface cables. Although not shown, the optical disk formatter controller 106 is connected to the optical disk drive devices 112 to 115 via an ESDI-C cable, which is an internal cable, because it is not directly related to the operation of this embodiment.

Next, in the second embodiment shown in FIG.
Description will be made assuming that only the optical disk drive 112 is provided in the optical disk subsystem basic unit 104 and the optical disk drive 113 is added. In this case, the addition is completed simply by connecting the optical disk drive 113 to the ESDI-B cable 107. That is,
The terminating resistor 116 has already been added to the terminating optical disk drive 112.
Therefore, it is not necessary to perform the termination setting operation.

Next, in the second embodiment shown in FIG.
Description will be made assuming that only the optical disc subsystem basic unit 104 is provided and the optical disc subsystem extension unit 105 is added. In this case, the external connection connectors 109a and 109b of the optical disk subsystem 104
Are initially connected by a bypass jumper cable 117 as shown in FIG. When the optical disk subsystem extension unit 105 is added, the bypass jumper cable 117 is removed from the external connection connectors 109a and 109b, and the external connection connectors 109a and 109b and the input connectors 110a and 110b are connected via the external extension cable 118. Connecting. Only by performing this operation, the expansion of the optical disk subsystem expansion unit 105 is completed. That is, since the terminating resistor 116 is already provided in the terminating optical disk drive 112, it is not necessary to perform the termination setting operation.

As is clear from the above description, according to the present embodiment, it is possible to perform the addition and relocation of the optical disk drive unit and the addition and relocation of the optical disk subsystem unit without performing the termination setting operation. it can.

[0019]

According to the present invention, it is possible to provide a daisy chain connection changing method which eliminates the need for termination setting operation when a device connected in a daisy chain is added or relocated.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram showing a connection state of an external connector of an optical disc subsystem basic unit in a case where an optical disc subsystem expansion unit is not provided in the second embodiment shown in FIG.

[Explanation of symbols]

1 Upper device 2 Basic subsystem 3a to 3k Expansion subsystem 4 Control device D1, D2 to Dn device 5a, 5b External connection terminal 6a, 6b Input terminal 7 Bypass cable 10 Internal interface cable 12 Termination resistor 14 Daisy chain type interface cable 101 Host device 102 SCSI interface cable 103 SCSI input / output connector 104 Optical disc subsystem basic unit 105 Optical disc subsystem expansion unit 106 Optical disc formatter controller 107, 108 ESDI-B cable (daisy chain type interface cable) 109a, 109b External connection connector 110a, 110b input connector 118 external extension cable

Claims (1)

Claim: What is claimed is: 1. A control device configured to control a plurality of devices in response to a command from a host device, and a plurality of devices daisy-chained to the control device. In the system, a terminating resistor is installed in the device connected to the lowest of the plurality of devices, and the devices connected in the daisy chain are connected without changing the connection of the device in which the terminating resistor is installed from the lowest. A daisy chain connection changing method characterized by adding / moving