JPH03224049A - Connection device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a connection device for a Centronics interface.

[Prior Art] Conventionally, in a system using this type of device, when the input device is set to a desired mode before outputting data to the output device, for example, a laser beam printer is used as the output device. If used, the input device, such as a word processor, must first be used to set the mode of the laser beam printer.

Conventionally, this mode setting has been performed when printing for the first time after starting up an input device, or when printing for the first time after an output device is powered off and then turned on again.

[Problem that the invention seeks to solve] However,
With conventional Centronics connection devices, when one output device is shared by multiple input devices, if the mode setting differs depending on the input device, the mode setting will be overwritten by the other input device. There was a problem in that the mode was not set.

Means for Solving Problem E] In order to solve the above problem, the connection device of the present invention includes a connection means for connecting one of a plurality of Centronics input sections and a Centronics output section, and a connection by the connection means. a disconnecting means for disconnecting a device connected to the Centronics output section; a notification means for notifying a device connected to the Centronics input section of the energization state of the device connected to the Centronics output section; and a control means for controlling the notification means to notify the de-energized state.

[For use] According to the present invention, when the Centronics interface is disconnected by the disconnection means, the notification means notifies the input side that the power has been turned off, so that it is determined that the power of the output side equipment has been turned off. This is to have the mode set.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an example of the input/output configuration of a connecting device according to the present invention. As shown in the figure, in this embodiment, four inputs (
INO~3) and one output (OUT), and in a standby state (not connected to anything), connects the input device and output device that received the most data first.

The data transfer mechanism of Centronics is well known (as shown in the timing diagram in Figure 2, data is latched by a strobe signal. Normally, a strobe is about 1 microsecond, and several microseconds before and after that. If the data bus holds valid data for about a second time, the transfer will be performed correctly.

FIG. 3 is a block diagram showing the main parts of the internal configuration of the connection device of this embodiment.

In the figure, 1o and 12 are selectors, which select the signal line from the input by a selection signal a and output the selected signal line. 20 is an encoder that encodes the strobe. A latch 21 latches the output of the encoder using a latch signal and generates a selection signal a. Reference numeral 30 denotes an OR circuit, which generates a latch signal S in response to a strobe from one of the hosts 0 to 3. 40 is a retriggerable timer;
The latch signal is activated by the strobe signal d, and generates the signal C until a timeout occurs after a certain period of time. 5
0 is a gate, and the strobe signal from the selector 12 is gated by the signal C. 60 is a pulse generator which generates a pulse of a certain length when the signal C ends. A selector 70 outputs the pulse from the pulse generator 60 to the host selected by the selection signal a, similar to 10.12.

Next, the operation of the connecting device of the present invention will be explained.

First, in a standby state where the timer 40 has timed out (a state where the machine is not connected to anything), a strobe is issued to output data from one of the four host machines. The strobe from the host is an OR circuit 30
and generates a latch signal. The latch signal A latches the output from the encoder 20 in the latch circuit 21, generates the selection signal a, and starts the timer 40.

When activated, timer 40 generates signal C, disables OR circuit 30 to prevent switching due to strobes from other hosts, and enables gate 50 to open the gate for the strobe signal. The previously generated selection signal a enters the selectors 10 to 12, one of the four inputs is selected, and the selected data and strobe are output.

After the connection is established as described above, the timer 40 is restarted by the strobe signal d as long as the strobe is received from the host within a certain period of time, and the timer 40 does not time out (the connection state is maintained).

When the strobe is interrupted for a certain period of time or more, the timer 40 times out and the signal C is turned off. Then, the strobe gate 50 is closed and the pulse generator 6 is closed.
0 generates a pulse of constant length. This pulse enters the selector 70, and for the host selected by the selection signal a, turns off the signal that indicates on the host side that the output side power is ON by the pulse length. At the same time, signal C enables OR circuit 30, allowing switching and returning to the standby state.

[Other Examples] In this example, the disconnection is performed using a retriggerable timer, but other methods may be used.

Furthermore, although this embodiment has described a mode in which the input boat and the output boat are integrated, the input and output are located at different locations.
Even if the devices are connected via a network, this does not detract from the spirit of the present invention.

[Effects of the Invention] As explained above, according to the present invention, when disconnecting the connection device, a power-off is displayed on the input side for a certain period of time, so that the device on the input side is not powered on when the output device is powered off. The device can be configured to determine that the device has been turned on again after being disconnected, and to set the mode for the next output, allowing the same output device to be shared among multiple human-powered devices that have different mode settings.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the input/output configuration of the connecting device, FIG. 2 is a diagram showing the timing of data transfer, and FIG. 3 is a block diagram of the connecting device. In the figure, l is the connection device, 10.12.70 is the selector, 2
0 is an encoder, 21 is a latch, 30 is an OR circuit, 4
0 is a timer, 50 is a gate, and 60 is a pulse generator.

Claims (1)

[Claims] (1) A connection device having a plurality of Centronics input sections and a Centronics output section, the connection device connecting one of the plurality of Centronics input sections and the Centronics output section, and disconnecting the connection by the connection means. a disconnection means for notifying a device connected to the Centronics input section of the energization state of the device connected to the Centronics output section; when the disconnection section disconnects the connection by the connection means; A connection device comprising: control means for controlling the notification means to notify a non-energized state.