JPS6225542A - Communication equipment - Google Patents

Abstract

PURPOSE:To remarkably improve the operability by fixing a control signal to a predetermined level when a detection means detects the floating level. CONSTITUTION:When the floating level is detected by a detection circuit 4 at the step S1, insce an opposite device does not use the control signal, the output of the circuit 4 goes to '0' level. When the output reaches '0' level, a gate of a gate circuit 5 is closed and the transmission of the output of a receiver 3 to a line 6 is inhibited. Simultaneously, the output of the circuit 5 is fixed to the '0' level. The '0' level of an enable signal level of the line 6 and the operation is similar to it that as if a permission level of a CTS signal were sent always from the opposite device. Thus, the operability is improved remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a communication device having a serial transmission interface based on the 11-step synchronization method, and particularly relates to processing of control signals.

[Prior Art] Conventionally, in this type of device, the definition of the serial transmission interface is ambiguous, or the interface signal is allowed to be selectively used, so the same serial transmission interface Even in the case where the control input/output was different depending on each device.

[Problems to be Solved by the Invention] For this reason, in devices that can connect various devices to VC, it is necessary to use jumper plugs or changeover switches to internally set signal lines that are not used by the other device to a fixed level. The disadvantage was that it required additional operations.

SUMMARY OF THE INVENTION In view of the above-mentioned points, an object of the present invention is to enable operation by connecting a connector without the operator having to know the convenience of the control signal of the phaser device, thereby improving operability. The object of the present invention is to provide a communication device with improved performance.

In order to achieve the above object, the present invention provides a communication device δ having a terminal for receiving a control signal from the outside.
The AfIR is a combination of detection means for detecting a floating state of a terminal, and means for fixing a control signal to a predetermined level when the detection means detects a floating state.

[Function] That is, in the present invention, when the detection means detects a floating state, the control signal is fixed at a predetermined level.

Examples The present invention will now be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a control signal input circuit of a serial transmission interface section of a communication device of the present invention.

In the figure, the communication control IC 12 that performs serial/parallel conversion of data for communication is a connector for inputting control signals, and here, for example, CTS (cIear to 5end) indicates whether transmission is possible or not. This is a CTS signal connector that accepts signals. 3 is a receiver that receives a signal from the connector 2 for the CTS signal, and 4 is a floating level detection circuit that determines the floating level of the connector 2 and sends an output to that effect.

5 is a gate circuit that allows the output signal from the receiver 3 to pass according to the detection output of the floating level detection circuit 4;
Reference numeral 6 denotes a control signal input line to the communication control circuit C1, and here it is a line for GTS signals.

Next, an example of the operation of the circuit shown in FIG. 751 will be described below with reference to the flowchart in FIG.

First, when the device is powered on, the floating level detection circuit 4 operates and determines the floating state of the connector 2 (step St). That is, if the other device uses it as an output signal, it is detected as a signal level, and the output of the floating level detection circuit 4 becomes "1" level (step S2). When this output reaches the "1" level, the gate of the gate circuit 5 is opened (step S
3) Is 3 the connector to/from the cash register? The signal received at is directly output to line 6 and input to the communication control ICI (step S4). The following is normal operation.

On the other hand, if the floating level is detected by the detection circuit 4 in step S1, the partner device is not using this control signal, so the lfj force of the floating level detection circuit 4 is -O''. level (step S5).When the output reaches the "'0" level in this way,
The gate of gate circuit 5 is closed and the output of receiver 3 is prohibited from being transmitted to line 6 (step 7 S
8) At the same time, the 1B power of the gate circuit 5 becomes “0”.
It is fixed at the level (step S7). This "'O level" is the enable signal level of line 6, and the operation is the same as if the enable level of the GTS signal was always being sent from the partner device.

As explained above, according to this embodiment, since the floating level detection circuit and the gate circuit that performs the same control as when the enable level is input at the 70-ting level are provided, the other device cannot use the control signal. If it is, the gl control operation based on the control signal remains valid, and on the other hand, if it is not in use, it is assumed that it has been internally enabled. As a result, the operator only needs to connect the connector without having to know the status of the partner device, which has the effect of making the operation extremely easy.

[Effects of the Invention] As explained above, according to the present invention, when the detection UB means detects a floating state, the control signal is fixed at a predetermined level, so that operability is significantly improved. can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a control signal input circuit of a serial transmission interface section of a communication device of the present invention. FIG. 2 is a flowchart showing an example of control of the circuit shown in FIG. l...ICl for communication control 3...Regiver, 4...Floating level detection circuit, 5...Gate circuit 6 Fig. 1 Fig. 2

Claims (1)

[Scope of Claim] A communication device having a terminal that accepts a control signal from the outside, comprising: detection means for detecting a floating state of the terminal; and a control signal that is determined in advance when the detection means detects the floating state. A communication device characterized by comprising: means for fixing to a level.