JPH0580902A - Information processor - Google Patents

Abstract

PURPOSE:To automatically connect or disconnect the terminating resistor with a bus interface by detecting whether or not a plug is connected to sockets. CONSTITUTION:The information processor equipped with the sockets 2 and 3 and terminating resistor elements 10-13 has a detecting means which detects whether or not the plug 1 is connected to the sockets 2 and 3 and a means which makes the terminating resistor elements 10-13 effective when the detecting means detects the socket 3 where the plug is not connected, but makes the terminating resistor elements 10-13 ineffective when the detecting means detects the plug being connected to all the sockets.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information processing apparatus capable of connecting a bus interface which requires a terminating resistance element.

[0002]

2. Description of the Related Art In a bus interface connecting a plurality of information processing devices or peripheral devices, there are cases where a terminating resistance element needs to be connected and cases where it is not necessary, depending on the number and configuration of devices to be connected.

[0003]

In the above-mentioned conventional configuration, when the number of devices to be connected is increased or decreased or the connection configuration is changed, the terminating resistor needs to be activated (connected state) or disconnected. On the other hand, conventionally, it has been necessary to judge whether or not a person is the terminal and perform the operation of connecting or disconnecting the terminal resistance element.

[0004]

According to the present invention, when the device body has a plurality of sockets, a detecting means for detecting whether or not a plug is connected to the plurality of sockets, When the detecting means detects the presence of a socket in which no plug is mounted, the terminating resistance element is activated (activated), and when the detecting means detects that the plugs are mounted in all the sockets, It has means for invalidating (separating) the termination resistance element.

For example, in the case where the device body has two sockets, when the detecting means detects that the plug is attached to only one of the sockets, it is judged as the termination and the termination resistance is activated, When it is detected that the plugs are attached to both of the sockets, it is determined that it is not the termination and the processing for disconnecting the termination resistor is executed. In this way, by automatically determining the termination, the termination resistor is activated if it is the termination, and the termination resistor is disconnected if it is not the termination.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.
Will be described in detail based on.

In the figure, reference numeral 1 is a plug which is connected to another device via a cable.

Reference numerals 2 and 3 are sockets attached to the main body of the apparatus, 2 is an A socket, and 3 is a B socket. The A socket and the B socket are connected to the same signal line.

In FIG. 1, 4 and 5 are microswitches each having one terminal connected to GND.

When the plug 1 is attached to the A socket 2, 4a is pushed by the plug 1 to turn the micro switch 4 into the "on" state, and when not attached, the micro switch 4 is not pushed into the "off" state. It is a contactor.

When a plug (not shown) is attached to the B socket 3, 5a is pushed by the plug to bring the microswitch 5 into the "on" state, and when it is not attached, it is not pushed so that it is "off". It is a contactor that makes the state.

Reference numeral 6 denotes a NOR gate for inputting the signals S1 and S2, which inputs the output signal S1 from the microswitch 4 which is not GND, and inputs from the microswitch 5 to GND.
The other output signal S2 is input.

Reference numeral 7 is a pull-up resistor for the signal S1, and 8
Is a pull-up resistor for the signal S2.

Reference numeral 9 is an inverter which receives the output signal S3 of the NOR gate 6 and outputs a signal S4.

10 to 13 are resistances, and 10
Is a pull-up resistor for terminating the signal S5, and 11 is a pull-down resistor for terminating the signal S5. Further, 12 is a pull-up resistor for terminating the signal S6, and 13 is a pull-down resistor for terminating the signal S6. The signals S5 and S6 are signals of the bus interface.

Reference numeral 14 is a pull-up resistor 1 for terminating the signal S5.
Reference numeral 16 is a switching transistor for determining whether 0 is connected to VCC, and 16 is a switching transistor for determining whether the termination pull-up resistor 12 for the signal S6 is connected to VCC. "ON" or "OFF" of the switching transistors 14 and 16 is determined by the signal S3.

Reference numeral 15 is a pull-down resistor 1 for terminating the signal S5.
1 is a switching transistor for deciding whether to connect 1 to GND, and 17 is a switching transistor for deciding whether to connect the termination pull-down resistor 13 of the signal S6 to GND. "ON" or "OFF" of the switching transistors 15 and 17 is determined by the signal S4.

Reference numeral 18 is a base current limiting resistor of the switching transistor 14, and 19 is a base current limiting resistor of the switching transistor 15. Further, 20 is a base current limiting resistor of the switching transistor 16, and 21 is a base current limiting resistor of the switching transistor 17. And, 18 and 19 and 24 and 25 are bias resistors.

Next, the operation of the circuit will be described based on the above configuration.

When the plug 1 is installed in the A socket 2 of FIG. 1 and the plug is not installed in the B socket 3, this device must be regarded as a terminal and the terminal resistor must be activated.

In this case, since the switch 4 is "on" and the switch 5 is "off", the signal S1 is "L" signal S.
2 becomes "H" and the output signal of the NOR gate 6 is "H".
become.

As a result, the base current limiting resistor 18
Since the switching transistor 14 is turned “on” via, the terminating resistor 10 is connected to VCC and becomes active.

On the other hand, since the output signal S4 of the inverter 9 becomes "L", the switching transistor 15 is turned "on" through the base current limiting resistor 19, and the terminating resistor 11 is connected to GND and becomes active. Become.

When the plug 1 is attached to the A socket 2 of FIG. 1 and the plug is attached to the B socket 3 as well, it is necessary to disconnect the terminating resistor assuming that this device is not the termination.

In this case, since the switch 4 is turned "on" and the switch 5 is also turned "on", the signal S1 becomes "L" signal S.
2 also becomes "L" and the output signal of the NOR gate 6 is "L".
become.

As a result, the base current limiting resistor 18
Since the switching transistor 14 is turned “OFF” via the, the terminating resistor 10 is disconnected from VCC.

On the other hand, since the output signal S4 of the inverter 9 becomes "H", the switching transistor 15 is turned "off" through the base current limiting resistor 19, and the terminating resistor 11 is disconnected from GND. As described above, the termination resistors 10 and 11 are validated (connected state) or invalidated (disconnected). The same applies to the terminating resistors 12 and 13.

FIG. 2 shows another embodiment of the present invention in which the broken line portion D in FIG. 1 is changed.

In FIG. 2, reference numerals 30 and 31 denote the microswitches 4 and 5 in FIG.

Since the plug 1 is mounted in the A socket 2 in FIG. 2, the output light of the light emitting diode LED incorporated in the photo coupler 30 is reflected by the plug 1 to turn on the photo transistor PT incorporated therein. To On the other hand, since the B socket 3 has no plug attached,
The photocoupler 31 has a built-in light emitting diode LED
Since the output light of is reflected and does not return, the built-in phototransistor PT is turned off. And the signal S
1 and the signal S2 are the same as in FIG.

[0031]

As described above, according to the present invention, it is possible to automatically connect and disconnect the terminating resistor by judging the connection state of the plug to the socket, so that the operability of the device is improved.

[Brief description of drawings]

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

FIG. 2 is a configuration diagram of a main part showing another embodiment of the present invention.

[Explanation of symbols]

 1 Plug 2,3 Socket 4,5 Micro Switch 4a, 5a Contact 14,15,16,17 Switch Transistor 10,11,12,13 Termination Resistor

Claims (1)

[Claims] 1. An information processing apparatus comprising a plurality of sockets and a terminating resistance element, wherein a detecting means for detecting whether or not a plug is connected to the plurality of sockets, and the detecting means is a plug. The terminal resistance element is enabled when it detects the presence of unattached sockets, and the means for disabling the terminal resistance element when the detection means detects that plugs are mounted in all sockets. An information processing device characterized by the above.