JPS62209648A - Data transfer controller - Google Patents

Abstract

PURPOSE:To enable an operator to perform operations regardless of the working state of an input/output device by actuating a switch means in response to the operations of a communication means and a detecting means. CONSTITUTION:The signal lines 14 and 15 are provided as detecting means together with CPU 1 and 2 as host computers, a control part 10 as a communication means, interface signals 17 and 18, a connection switch circuit 11 as a switching means, and an image reader 4 and an image printer 5 as input and output devices respectively. The part 10 detects the states of the reader 4 and the printer 5 through both lines 14 and 15 and the controls the connection between the CPU 1 or 2 and the reader 4 and the printer 5 respectively by a command produced by the signals 17 and 18 given from the CPU 1 or 2. While the connection to input and output devices carried out by a command is inhibited while both devices are working or when one of both CPU is busy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data control device, and more particularly to a data transmission control device for sharing an input/output device among a plurality of central processing units.

[Prior Art] In a conventional system, such as an image processing system, each central processing unit (hereinafter referred to as CPU) is connected to at least one image input device such as an image reader, and at least one image output device such as an image printer. in many cases.

However, in this type of system, the proportion of use of these image input/output devices in the overall processing time is extremely small, and despite this usage situation, each c
Connecting expensive image input/output devices to each PU is extremely wasteful. For this reason, a system has also been proposed in which a printer control device generally called a print server is provided and the printer is shared by a plurality of CPUs via a local area network (hereinafter referred to as LAN). However, such a system requires extensive LAN control and shared control, and is not suitable for small-scale shared control.

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned conventional example, and an object of the present invention is to provide a simple data transmission control device in which an input/output device can be shared by a plurality of CPUs.

[Means for solving the problem] As a means for solving this problem, for example, the data sharing control device of the embodiment shown in FIG.
, 2, a control section 10 as a communication means, an interface signal 17, 18, a connection switching circuit 11 as a switching means, and an image reader 4 and an image printer 5 as input/output devices.

[In the configuration shown in FIG.
．． 15 detects the status of the image reader 4 and image printer 5, and according to commands from the interface signal 17.18 from the CPUI or 2.
The connection between the image reader 4 and the image printer 5 is controlled. Connection with the input/output device using the above command is not performed when the input/output device is in operation or in use by another CPU.

[Example] An example of the present invention will be described in detail below with reference to the drawings.

[Connection diagram (FIG. 2)] FIG. 2 is a connection diagram showing an embodiment according to the present invention. 1
．． 2 is C1 (υ), which shares an image reader 4 and an image printer 5 via a shared control device 2.The image reader 4 inputs the reflected light of the original image to a photoelectric conversion element by optical means, The element converts input light into an electrical signal train and outputs it as image data.

The image printer 5 receives image data in the form of an electrical signal train and reproduces the image on paper as a dot image. This image printer is a so-called laser beam printer, which scans a laser beam to form a latent image corresponding to data on a photosensitive drum, and prints it on paper by development and transfer, or a printer with electrostatic electrodes. An electrostatic printer, an inkjet printer that prints by ejecting ink droplets, a thermal printer (including a thermal transfer printer) that prints by heat-sensitive coloring, etc. can be used. Further, the image reader 4 can also be directly connected to the image printer 5 to function as a copying machine.

The shared control device 3 connects a predetermined CPU and the image reader 4 or the image printer 5 in response to a connection request from the CPUI or the CPU 2. Furthermore, when neither of the CPUs 1.2 is using the image reader 4 or the image printer 5, the image reader 4 and the image printer 5 are automatically connected and can be used as a copying machine. ing.

[Configuration Diagram of Shared Control Device (FIG. 1) FIG. 1 is a block diagram showing the configuration of a shared control device 3 according to an embodiment of the present invention.

A connection switching circuit 11 switches the connection between the image reader 4 and image printer 5 and the CPU 2 in response to a switching signal 16 from the control unit 10. Note that some of the interface signals of the image reader 4 and the image printer 5 are input to the control section 15 as status signals through signal lines 14 and 15, respectively, and the control section 15 controls the image reader and the image printer based on these status signals. 4 and the image printer 5 are monitored. Reference numeral 10 denotes a control unit that receives various status signals and interface signals 17.
18, and includes a microprocessor (MPU) 100, a ROMI (M) containing its control programs and data, and a RAMIO 2 as a work area.

17.18 are shared II from CPU1 and CPU2 respectively
This is a control signal input to the control unit 10 for J#, and here data transmission and reception using serial data is performed.

19.21 are image reader interface signals of CPU1 and CPtJ2, respectively, and 20.22 are image printer interface signals of CPUI and CPU2, respectively.

12.13 is a switch in the connection switching circuit 11, which operates in conjunction with each other to switch the contact between A and C according to the switching signal 16 from the control unit 10, and switches between each CPU, the image reader 4, and the image. Controls the connection of the printer 5.

The image reader interface signal 23 and the image printer interface signal 24 are broadly divided into communication signals for communicating commands and status, and image signals for inputting and outputting image data. The human output direction of the image system signal is opposite to that of the image printer interface signal 24.

When functioning as a copying machine, the image reader 4 is in a mode in which it directly controls the image printer 5 as a master card, and this mode is called an offline mode. At this time, the switching signal 16 from the control section 10 causes the switch 12.
13 is switched to the contact C side.

On the other hand, when connected to either cput, 2, the image reader 4 operates in slave mode, and the CPU
1. The lifting operation is performed by the control in 2. This mode is called online mode. For example, when the copy start key of the image reader 4 is pressed in offline mode, the image reader 4 starts reading the image.
The image data is sent to the image printer 5 to be printed, and the image printer 5 performs a copying operation as a copying machine.

Note that such switching between online mode and offline mode is performed by issuing an online command or an offline command to the image reader 4 from the control unit 1o via the signal line 14 using the communication system signal of the image reader interface signal. be exposed.

Interface signals 17 and 18 are serial interface signals commonly known as R3232C, and through this serial interface signal,
The control unit io is CPUI.

2 and communicates commands and status for shared control. If the CPU 1 now wants to use the image printer 5, the CPU checks the status of the shared control device 3 through the interface signal 17, issues an oven command if the image printer 5 is available, and
declare that it is for exclusive use. When the oven command is accepted and the exclusive state is established, predetermined printing is performed, and after printing is completed, a close command is issued to declare the release of the exclusive state, and the series of sequences ends.

When the control unit 10 switches the connection state with the connection switching circuit 11, depending on the operating states of the image reader 4 and the image printer 5, switching may not be necessary. First of all, this is when the image reader 4 and the image printer 5 are in exclusive use of the CPUI or the CPU 2, which means the period from receiving the oven command from the CPU to receiving the close command. Second, it must be prohibited during offline mode, that is, during so-called local copying, in which the machine operates as a copying machine even when no CPU is occupied. For this reason, the control unit 1
0 needs to intercept the communication between the image reader 4 and the image printer 5 by monitoring the communication system signal of the image reader interface signal, and detect whether or not the copying period is in progress.

The sequence of copy operations is as follows. First, the photosensitive drum of the image printer 5 is rotated, and when the rotation reaches a certain number of rotations, paper is fed from the paper cassette to a predetermined starting position. The above is the copy preparation stage, and then copying is performed by synchronizing the read operation of the image reader 4 and the print operation of the image printer 5. After the paper is ejected, the rotation of the photosensitive drum is stopped, and a check is made to see if there are any abnormalities such as jams, and a series of copying operations is completed. Therefore, the control unit 10 uses the image reader 4
Intercepts communication between the image printer 5 and the image printer 5, detects the period from the photosensitive drum rotation start command to the end status after the photosensitive drum rotation stop command, detects the copying period, and sets a switching prohibition period. .

Communication system signals such as image reader interface signals and image printer interface signals are both designed to always return a status in response to a command, so from the time these commands are issued until the status is returned, the signal is Of course, switching should not be performed.

[Explanation of Operation of Shared Control Device (FIG. 3)] FIG. 3 is a flowchart of the reception operation from the CPU of the MPU 100, which is stored in the ROM 101 of the control unit 10 of the shared control device 3.

First, when an oven command is received from CPU I or 2 in step S1, the process proceeds to step S2 to check the usage status of other CPUs. Assuming that there is now an oven command from the CPUI, if the CPU 2 is not in use, the process advances to step S3 to check whether or not copying is in progress. When copying is in progress or when CPU2 is in use in step S2, the process advances to step S4, and an unacceptable message is sent to CPU1.

When no CPU is in use, in so-called offline mode, and when copying is not in progress, that is, when the image reader 4 and image printer 5 are available, an online command is issued to the image reader 4 in step S5, and the offline mode is activated. Switch to online mode.

In step S6, the switching signal 16 is output and the CPU 12 is connected to the contact A of the switch 12.13 so as to connect the image reader 4 and the image printer 5. This puts CPU 1 in exclusive use. In step S7, a check is made to see if a close command is received from the CPU, and if so, the process proceeds to step S8, where the switching signal 16 switches the contacts of the switches 12 and 13 from A to C. In step S9, an offline command is issued to the image reader 4 to switch from online mode to offline mode and put it in an online standby state.

[State i! Explanation of Diagram f5 (FIG. 4)] FIG. 4 is a state transition diagram showing the state transitions of the image reader 4, image printer 5, and shared control device 3.

After the power is turned on, a predetermined initialization process is performed at 40, and then the offline mode is entered at state 41 to enter an offline standby state. When an exclusive request (oven command) is issued from CPtJl, 2, an online command is issued to the image reader 4 to shift to state 41,
Switched to online mode, depending on whether the oven is from the CPUI or the oven from CPU2, it becomes exclusive to CPU1 or 'CPU2, and enters state 43 or 44.
to move to.

CPUI or CPU2<7) From the exclusive state, cpU1
By the close or CPU2 close command, it enters an online standby state, automatically issues an offline command to the image reader 4, moves from state 42 to state fi41 for 8 lines, and returns to a standby state.

If the copy start key is pressed during offline standby,
The process goes to state 45 for 8 lines, performs local copying, returns to state 41 again upon completion, and enters the offline standby state.

In addition, although the present embodiment/example has been described using two CPUs, the present invention is not limited to this, and the number of CPUs can be used without any limit.

Further, although R5232C is used as the serial interface signal for shared control, other serial interface signals or even a parallel interface may be used.

Furthermore, although the connection switching circuit 11 switches the image reader interface signal and the image printer interface signal to the same CPU at the same time, the connection switching circuit 11 may switch the image reader interface signal and the image printer interface signal to different CPUs at different timings.

As described above, various modifications and variations can be made without departing from the gist of the present invention.

Although the input/output device in this embodiment has been described as an image input/output device, it is needless to say that the input/output device is not limited to this and may be any other input/output device.

As described above, this embodiment has the advantage that a plurality of central processing units can share an image input/output device without changing the original interface signal of the image input/output device.

[Effects of the Invention] As described above, according to the present invention, an input/output device can be shared by multiple CPUs with a simple configuration, and an operator can operate the input/output device without worrying about the operating state of the device. effective.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a shared control device according to an embodiment of the present invention, Fig. 2 is a diagram showing connections of the shared control device according to this embodiment, Fig. 3 is a flowchart of the receiving operation of the control unit, and Fig. 4 is It is a state transition diagram of a shared control device. In the figure, 1.2...CPU, 3...Shared control device, 4
...Image reader, 5...Image printer, 1
0...Control unit, 11...Connection switching circuit, 12.13
...Switch, 14.15...Signal line, 16...
Switching signal, 17.18...interface signal. Patent applicant Canon Co., Ltd. Figure 1

Claims (3)

[Claims] (1) A data transmission control device interposed between a plurality of host computers and an input/output device, which includes a detection means for detecting the state of the input/output device, a means for communicating with the host computer, and a means for communicating between the host computer and the input/output device. A data transmission control device comprising: switching means for switching connection of an output device, wherein the switching means operates in correspondence with the communication means and the detection means. (2) The data transmission control device according to claim 1, wherein a switching prohibition section of the switching means is detected by the detection means and the communication means. (3) The data transmission control device according to claim 1, wherein the input/output devices are an image reader and an image printer.