JPH06214949A - Communication equipment and its communication method - Google Patents

Abstract

PURPOSE:To read out stored contents in an image forming device or an external storage device from a main controller by permitting the main controller to receive data from the image forming device or the external storage device by way of SCSI. CONSTITUTION:This equipment is provided with the main controller 101 such as a host computer, etc., a host adapter 101a operating as target A, SCSI(Small Computer System Interface) bus 102, the image forming device 103 such as a printer, etc., a printer controller 103a as an initiator, the external storage device 104 such as a hard disk device, etc., and a controller 104a functioning as a target B. Then, a main control part receives data from the image forming device 103 by way of its SCSI or from the external storage device 104 by way of SCSI.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device and a communication method for connecting a plurality of devices for communication.

[0002]

2. Description of the Related Art Some image forming apparatuses such as printers can be connected to an external storage device such as a hard disk device for storing character fonts and temporarily storing print data. Such a printer device and a hard disk device are SCSI (ANSI X3.131-1).
986), and the printer device accesses the hard disk through this interface.

[0003]

In such a conventional configuration, the hard disk device can transfer data only with the printer device, and the main controller such as a host computer can directly access the hard disk device. could not.

A connection method using RS232C is known as an interface for connecting these various devices. The RS232C cable has the same RS2, as called a cross cable and a straight cable.
Even if the connection is by 3C, the connection format may be different. Therefore, by mistake RS23C for cross cable
When a straight cable is connected to the interface connector, there is a problem that signal collision occurs and the internal driver IC is damaged.

The present invention has been made in view of the above conventional example, and provides a communication method capable of reading the contents stored in the image forming apparatus or the contents stored in the external storage device from the main control device. With the goal.

It is another object of the present invention to provide a communication device capable of connecting devices using a connection cable regardless of the RS23C connection method.

[0007]

In order to achieve the above object, the communication method of the present invention has the following configuration. That is,
A communication method in a communication device for connecting at least a main control device and an image forming device via SCSI, wherein an external storage device is connected via the SCSI, and the main control device is connected to the image forming device via the SCSI. Alternatively, the data is received from the external storage device.

In order to achieve the above object, the communication device of the present invention has the following configuration. That is, a communication device connected by an RS232C cable, the determining means for determining the signal level of the transmission / reception data signal in the RS23C interface signal, the transmission driver for transmitting the transmission data signal, and the reception driver for receiving the reception data signal. A transmission / reception circuit for connecting a driver to the transmission / reception data signal, selection means for selecting either the transmission driver or the reception driver according to the signal level judged by the judgment means, and selection by the selection means And a communication unit that performs transmission and reception using the created driver.

[0009]

According to the communication method of the present invention, the main control unit is the SCS.
The image forming apparatus and the external storage device are connected via I, and the main control device receives data from the image forming apparatus or the external storage device via the SCSI.

According to the communication device of the present invention, the RS23
The signal level of the transmission / reception data signal in the C interface signal is determined, and either the transmitting driver or the receiving driver is selected according to the determined signal level,
It operates so as to transmit and receive using the selected driver.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram showing the configuration of a printing system according to an embodiment of the present invention. In FIG. 1, 101 is a main control device such as a host computer, 101a is a host adapter, and operates as a target A here. 10
2 is a SCSI (Small Computer System Interface) bus, 103 is an image forming apparatus such as a printer, 103a
Is a printer controller, which functions as an initiator here. Reference numeral 104 denotes an external storage device such as a hard disk device, and 104a denotes its controller, which functions as a target B. As is well known, this SC
In the SI specification, any controller or adapter connected to SCSI can be the initiator or target.

First, a case will be described in which the printer device 103 acts as an initiator, reads data from the disk device 104, and sends the contents to the host computer 101. Although various cases can be considered, here, as shown in FIG. 1, it is assumed that the printer device 103 is the initiator, the host computer 101 is the target A, and the disk device 104 is the target B.

First, in the arbitration phase, the printer controller 103a is set as the initiator, and in the next selection phase, the disk controller 104a is designated as the target. Then, in the information transfer phase, the printer controller 103a, which is the initiator, causes the disk controller 1
The data transfer direction is designated for 04a, and data is exchanged between the initiator and the target.

FIG. 2 shows a target (disk device 104).
7 is a flowchart showing data transfer to a more initiator (printer device 103).

First, in step S1, it is determined whether the ACK output from the initiator (printer device 103) is off. If it is off, the process proceeds to step S2, in which data is transferred from the target B (disk device 104) to the SCSI bus. Output. Then, in step S3, the target B is R
Turn on the EQ. As a result, the initiator (printer device 103) detects that the data is output, takes in the data, and simultaneously turns on ACK. Target B that this ACK is turned on
Is detected, the process proceeds to step S5, and REQ is turned off. Next, in step S6, it is checked whether or not there is data to be transferred from the target B to the initiator (printer device 103). If there is data to be transferred, step S6 is executed.
Returning to 1, the above-mentioned processing is repeatedly executed until there is no next data.

In this way, the printer device 103 can read the data stored in the disk device 104 which is an external storage device.

When the host computer 101 reads this data content from the printer device 103, which is the initiator, the initiator (printer device 10)
Data is transferred from 3) to the target A (host computer 101). This process is shown in the flowchart of FIG. Here, the printer device 103, which is the initiator, uses the host adapter 101a in the arbitration phase and the selection phase.
Is specified as the target.

First, in step S11, it is checked whether REQ from the target A (host adapter 101a) is turned on. If it is turned on, the process proceeds to step S12, and data is output from the initiator (printer device 103). Then, in step S13, the initiator (printer device 10
When 3) raises an ACK, the target A in step S4.
(Host computer 101) fetches the data and turns off REQ. Next, proceeding to step S15, the initiator (printer device 103) turns off ACK and returns to step S11. Thus step S
In step 16, the above processing is repeated until there is no data to be transferred from the initiator (printer device 103) to the target A (host computer 101), and data is transferred from the printer device 103 to the host computer 101.

In this way, the contents of the memory built in the printer device 103 are transferred to the host computer 101.
Can be displayed and displayed on the screen of the host side if necessary.

As another embodiment, similar to the configuration of FIG. 1, the interface specification is changed to GPIB I / F, the disk device 104 or printer device 103 side is used as a talker, and the host computer 101 side is used as a listener. By setting to, the host computer 101 can access the contents of the memory built in the printer device 103 or the contents stored in the disk device 104, as in the above-described embodiment.

Further, as shown in FIG. 4, the main controller 201
The external storage device 204 can be connected to the external storage device 204 via the SCSI bus 202, and the data stored in the external storage device 204 can be directly read by the main control device 201.

As described above, according to the first embodiment,
SCS between the main controller, the image forming apparatus, and the external forming apparatus
By connecting with I, the contents of the internal memory of the image forming apparatus or the data of the external storage device can be read from the main controller.

Thus, by displaying the contents on the screen of the main controller, the user can confirm the output data of the image forming apparatus or the data of the external storage device on the screen of the main controller.

Next, a second embodiment of the present invention will be described. In the second embodiment, even if the connection method of the RS232C cable used in a modem or the like is different, a device that can connect the RS232C cable and perform communication without considering the connection method will be described.

FIG. 5 shows RS2 in the case of a straight cable.
FIG. 6 is a diagram showing a connection example of a 32C driver / receiver, and FIG. 6 is a diagram showing a connection example of an RS232C driver / receiver in the case of a cross cable. Further, FIG. 7 shows a connection form between the connectors in the case of FIG. Note that the communication method here is asynchronous transmission, and it is assumed that the power supply on the B side has already been turned on and the RS232C control is in the standby state. On the other hand, in the RS232C driver / receiver 52 on the A side, the driver 53 that outputs T _X D is disabled because the switching signal 54 is initially set to the high level.

FIG. 8 is a diagram showing a connection example of a circuit for performing RS232C control including such an RS232C driver / receiver 52, and portions common to FIGS. 5 and 6 are indicated by the same numbers.

Now, as shown in FIG. 5, when connected via a straight cable, T _X output from the B side
Since the D signal is (+ 15V-5V) by default,
The detection signal 50 output from the voltage detection IC 51 becomes high level. On the other hand, when connected to a cross cable as shown in FIG. 6, the T _X D signal on the A side is connected to the input terminal of the R _X D signal on the B side, so the voltage detection IC
The input voltage of 51 becomes low level, and the signal level of the detection signal 50 output from this becomes low level.

As described above, the RS232C control circuit 70 of FIG.
It can be determined whether the 32C cable is a cross cable or a straight cable is output. When the 32C cable is a straight cable as shown in FIG. 5, the switching signal 54 is set to a high level to enable the receiving driver 55. On the other hand, as shown in FIG. 6, when it is connected to the cross cable, the switching signal 54 is set to low level to enable the driver 53 for transmission. This gives you what RS232
Even if the C cable is connected, RS232C will be changed accordingly.
Communication can be carried out by switching the terminals for.

In FIGS. 5 and 6, the T _X D signal and R
_Although the case of the XD signal is shown, other control signals RTS, CT
It goes without saying that the S, DTS and DSR are similarly switched. However, even in these cases, the determination of the cable is made by the signals T _X D and R _X D as described above.
Shall be carried out by

FIG. 9 is a flow chart showing the operation of the RS23C control circuit 70 of FIG. Here, first in step S21, it is checked whether or not the detection signal 50 from the voltage detection circuit 51 is at a high level, and if it is at a high level (FIG. 5).
(In the case of), the process proceeds to step S22, and the switching signal 54 is set to the high level. This enables the driver 55 for reception of the driver / receiver 52. On the other hand, if the detection signal 50 is low level (in the case of FIG. 6), step S
23, the switching signal 54 is set to low level. This enables the transmission driver 53 of the driver / receiver 52.

The voltage detection I in the second embodiment is
An operational amplifier can be used instead of C51.

In the second embodiment, the driver / receiver 5 is driven by the switching signal 54 from the RS232C control circuit 70.
I tried to switch between the two drivers, but the voltage detection IC
The driver 5 using the detection signal 50 output from 51
You may make it switch 3,55. Furthermore,
Since there are various connection methods for the cross cable, it is also possible to adopt a connection method suitable for them.

As described above, according to the second embodiment,
Even if the user mistakenly connects the cable, it is possible to prevent the occurrence of a device failure and automatically switch the signal according to the connection method to perform communication.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. Further, it goes without saying that the present invention can also be applied to the case where it is achieved by supplying a program for implementing the present invention to a system or an apparatus.

[0036]

As described above, according to the present invention, the contents stored in the image forming apparatus or the contents stored in the external storage device can be read from the main control device.

Further, according to the present invention, there is an effect that devices can be connected using a connection cable regardless of the connection method of RS23C.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a printing system according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing data transfer from a target to an initiator in the first embodiment.

FIG. 3 is a flowchart showing data transfer from an initiator to a target in the first embodiment.

FIG. 4 is a configuration diagram showing a modification of the first embodiment.

FIG. 5 is a diagram showing a connection example of an RS232C straight cable according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a connection example of an RS232C cross cable according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a connection example of an RS232C cross cable.

FIG. 8 is a diagram showing a connection example of devices using an RS232C cable in the second embodiment.

FIG. 9 is a flowchart showing a control example of the RS23C control circuit in the second embodiment.

[Explanation of symbols]

 50 detection signal 51 voltage detection IC 52 RS232C driver / receiver 53,55 driver 54 switching signal 101,201 main control device 101a host adapter 102,202 SCSI bus 103,203 printer device (image forming device) 103a printer controller 104, 204 disk Device (external storage device) 104a Disk controller

Claims (2)

[Claims] 1. A communication method in a communication device for connecting at least a main controller and an image forming apparatus via SCSI, wherein an external storage device is connected via the SCSI, and the main controller connects via the SCSI. And receiving data from the image forming apparatus or the external storage device. 2. A communication device connected by an RS232C cable, which comprises a judging means for judging a signal level of a transmission / reception data signal in an RS23C interface signal, a transmission driver for transmitting the transmission data signal and a reception data signal. A transmission / reception circuit for connecting a reception driver to the transmission / reception data signal, selection means for selecting either the transmission driver or the reception driver according to the signal level determined by the determination means, and the selection And a communication unit that performs transmission and reception using the driver selected by the unit.