JP2600495Y2 - Input / output signal switching circuit for POS terminal - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an input / output signal switching circuit for a POS terminal for monitoring a signal associated with a modem in a data terminal having a built-in or externally connected modem.

[0002]

2. Description of the Related Art A data terminal device, in particular, a point-of-sale information management system (Point of Sales System)
Some terminal devices (hereinafter referred to as POS terminal devices) in em) include a built-in modem or an externally connected modem, and exchange data with the central processing unit via the modem and an analog line.

In the case of a POS terminal of a type in which a modem is externally connected, the POS terminal is provided with an RS232C interface, and a modem signal related thereto is externally connected via an external modem connector (for example, D-sub 25p). Will connect to the modem. Therefore, when checking the operation of the POS terminal device related to the modem, it is possible to easily check the operation by guiding the modem signal to the monitor device via such an external modem connector and monitoring the modem signal.

[0004]

However, in a POS terminal having a built-in modem, signals transmitted and received between the internal communication serial control unit and the built-in modem are of TTL or CMOS level, and TTL / CM.
Some include a dedicated connector for guiding a signal consisting of the OS level. Therefore, even if an attempt is made to connect a monitoring device equipped with an external modem connector to the POS terminal device, the connection conditions do not match, such as different signal levels and different connector types. The connection cannot be made, and in order to connect the monitoring device to the POS terminal device, there is a problem that a signal level converter, a conversion cable, and the like for matching these connection conditions must be specially prepared. .

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and a simple connection can be made without requiring a signal level converter, a conversion cable and the like. It is another object of the present invention to provide an input / output signal switching circuit for a POS terminal device which can easily monitor a function as a POS terminal device by connecting an external modem or a monitoring device having a monitoring function by operation. .

[0006] An input / output signal switching circuit for a POS terminal device according to the present invention includes a serial circuit having a first transmitting circuit for transmitting a first transmitting signal and a first receiving circuit for receiving a second transmitting signal. A control unit, a second reception circuit for receiving a first transmission signal from the first transmission circuit, and a built-in modem having a second transmission circuit for transmitting the second transmission signal; And an AND gate circuit for taking the logical product of the transmitted signal and the third transmitted signal from the external modem, and sending the result of the logical product to the first receiving circuit; An OR gate circuit for calculating a logical sum with a third transmission signal and transmitting the result of the logical sum to the first receiving circuit of the serial control unit; a signal of the AND gate and an output signal of the OR gate; level A first driver for converting the signal level of the external modem; a second driver for converting the signal level of the first transmission signal to a signal level of the external modem; and a third driver for converting the signal level of the external modem. And a receiver for converting the transmission signal of the third mode to a logical signal level and transmitting the logical signal level to the OR gate and the AND gate, and transmitting the third transmission signal from the external modem to the receiver, or the first driver A switch for selectively switching the transmission of the converted transmission signal to the connector of the external modem, a second transmission signal from the internal modem, a third transmission signal from the external modem, and A function of monitoring a transmission signal from the serial control unit on a connector of the modem is provided.

[0007]

According to the present invention, when the built-in modem is connected to the serial control unit by the selective operation of the switch, the input / output signal switching circuit for the POS terminal device is provided with the first driver and the second driver. The transmission signal transmitted and received between the two via a driver can be guided to a connector of the external modem, and when the external modem is connected to the serial control unit, the serial control unit is connected in the connected state. In addition, based on the transmission signal transmitted and received between the external modems, the communication function of the POS terminal can be monitored, and the connection and operation required for such monitoring can be simplified.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an input / output signal switching circuit for a POS terminal device according to an embodiment of the present invention. In the drawing, a thick line represents a plurality of lines, and a thin line represents a single line.
In FIG. 1, (1) is a serial control unit for communication, which has a transmission circuit 1a and a reception circuit 1b. The transmission circuit 1a transmits a signal SD as a transmission signal on a line 1c.
(Transmission data), RS (transmission request) and ER (data terminal ready) are transmitted. The receiving circuit 1b connects a line 4a and a line 5b described below. (2) is a connector,
(3) is a modem built in the POS terminal device, and has a receiving circuit 3a and a transmitting circuit 3b. The receiving circuit 3a is connected to the line 1c via the connector (2). The transmission circuit 3b transmits the signal via the connector (2) via the line 3 as a transmission signal.
signals DR ′ (data set ready), CS of negative logic (only the signal of negative logic is indicated by adding “′”)
′ (Transmission enabled), CI ′ (callee indication), CD ′ (data channel reception carrier detection), ST 2 ′ (transmission signal element timing), RT ′ (reception signal element timing), and further, a connector (2 ) Via line 3d
The signal RD is transmitted above. (4) is an AND gate circuit which is activated by a negative logic input, and the input is connected to the line 3c
And a circuit connected to the line 8b and having an output connected to the line 4a, performing a logical AND operation between the signal on the line 3c and the signal on the line 8b, and sending a negative logic active output signal to the line 4a. It is.

[0008] (5) is an OR gate circuit, whose input is connected to the line 3d and the line 5a, and which takes a logical sum between the signal RD of the line 3d and the signal RD of the line 5a. OR
The output of gate circuit (5) is sent on line 5b.
(6) and (7) are RS-232C drivers. R
The input of the S-232C driver (6) is the line 4a and the line 5
b is connected to input a TTL level signal, and the output is connected to a line 6a to transmit a signal converted to an RS-232C level. The RS-232C driver (7)
Connect the input to line 1c to input a TTL level signal,
The output is connected to the line 7a, and the signal converted to the RS-232C level is transmitted. (8) is an RS-232C receiver, whose input is connected to a line 8a to input an RS-232C level signal, and whose output is connected to a line 5a and a line 8b to transmit a TTL level signal. . (9) is a switch having a first contact connected to the line 6a, a second contact connected to the line 9a, and a third contact connected to the line 8a. The third contact is selectively connected. (10) is a connector, and (11) is an external modem (or monitor device). The figure shows a state when an external modem is connected. The external modem is connected to a receiving circuit 11 connected to the line 7a via a connector (10).
a, and a transmitting circuit 11b to which a line 9a is connected via a connector (10), and further described here as having a modem monitoring function. When a monitor device (not shown) is connected, the transmission circuit 11b shown also becomes a reception circuit (not shown).

The signal of the RS-232C level is a negative logic signal, and a logic value "0" is set at 3V or more, and a logic value "1" is set at -3V or less. However, the RS-232C level RD signal is a positive logic signal, and a logic value “1” is set to 3 V or more and a logic value “0” is set to −3 V or less. The TTL level signal is 2.4 V when a 5 V power supply is used.
The above is a logical value “1”, and 0.4 V or less is a logical value “0”.
Is a normal logic signal.

The operation of the input / output signal switching circuit for a POS terminal having the above configuration will be described. When the POS terminal uses the external modem (11) (in the state shown in the figure), the connector (2) is disconnected, the internal modem (3) is disconnected, and the second contact of the switch (9) is closed. Connect to 3 contacts by jumper. Thus, the transmission signal transmitted from the transmission circuit 1a of the serial control unit (1) is transmitted to the line 1c and the RS-232C driver (7).
And to the receiving circuit 11a via the line 7a. On the other hand, the transmission signal transmitted from the transmission circuit 11b is
a, second contact, third contact of switch (9), wire 8a, R
The signal is input to the receiving circuit 1b via the S-232C receiver (8), the line 5a, the OR gate circuit (5), and the line 5b.
In this case, the output of the RS-232C receiver (8) is
The signal is also input to the AND gate circuit (4) via the line 8b. However, since the connector (2) is open,
All the lines 3c of the AND gate circuit (4) go high, and the output of the AND gate circuit (4) changes only according to the level of the signal on the line 8b. In addition, an external modem (1
The RD signal from 1) is sent from the RS-232C receiver (8) on line 5a and input to the OR gate circuit (5), but the other input of the OR gate circuit (5), that is, line 3
The input of d is fixed at a low level because the connector (2) is open. For this reason, the output of the OR gate circuit (5) changes according to the change of the high level / low level of only the signal on the line 5a.

With such a connection, signals are transmitted and received between the serial control unit (1) and the external modem (11). Therefore, in the external modem (11),
The user can receive a transmission signal transmitted to the serial control unit (1) and a transmission signal from the serial control unit (1) in response to the transmission signal, and monitor the function.

Next, the POS terminal device has a built-in modem (3).
When using the connector, the connector (2) is connected, the monitor device is connected to the connector (10), and the switch (9) is used.
Is connected to the first contact by a jumper. Thus, the signal of the transmission circuit 1a of the serial control unit (1) is transmitted to the reception circuit 3 via the connector (2).
a, and an RS-232C driver (7),
The signal is also input to a receiving circuit (not shown) of the monitor device (not shown) via the line 7a. On the other hand, the signal of the transmission circuit 3b of the built-in modem (3) is input to the AND gate circuit (4) via the line 3c. The signal on line 8b, which is the other input of the AND gate circuit (4), is all because the signal on line 8a, which is the input of the RS-232C receiver (8), is open at the third contact of the switch (9). It is fixed at the high level. Therefore, the output of the AND gate circuit (4) changes according to only the signal on the line 3c, and is input to the receiving circuit 1b via the line 4a. Also,
As described above, since the signal on line 8a, which is the input of the RS-232C receiver (8), is open at the third contact of the switch (9), the RS-232C (8) sent out on line 5a
Is fixed to a low level. Therefore, the output of the OR gate circuit (5) changes in accordance with only the line 3d and is input to the receiving circuit 1b via the line 5b.

In the embodiment of the present invention, as described above, the signal transmitted from the serial control unit (1) to the built-in modem (3) via the line 1c is monitored by the RS for monitoring.
232C driver (7) and a receiving circuit (not shown) of the monitor device via a line 7a. Furthermore, from the built-in modem (3) to the serial control unit (1)
The transmission signals on lines 4a and 5b are R
The signal is guided to a receiving circuit (not shown) of the monitor device via the S-232C driver (6), the line 6a, the first contact and the second contact of the serial control unit (1), the line 9a, and the connector (10). With such a connection, the monitor device monitors signals transmitted and received between the serial control unit (1) and the built-in modem (3), and monitors their functions.

[0014]

[Effects of the invention] As described above, according to the invention, PO
Even in the case of the internal modem of the S terminal device, the signal transmitted and received by the internal modem is transmitted to the POS through an existing connector provided for connecting an external modem by simply switching a switch.
It can be easily monitored by leading it out of the terminal device, and therefore, depending on whether the monitoring target is the case of the internal modem or the case of the external modem, the connection cable,
It is possible to easily monitor connectors and signal level conversion circuits without replacing or connecting them one by one.
This has the effect of facilitating operations such as maintenance and failure detection at the installation site of the OS terminal device. Furthermore, when implementing the present invention, it is only necessary to add a simple logic circuit including an AND gate and an OR gate to the POS terminal device, so that the present invention can be easily realized without greatly complicating the device itself. There is also an effect that can be done.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an input / output signal switching circuit for a POS terminal device according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Serial control unit 1a, 3b, 11b Transmission circuit 1b, 3a, 11a Receiving circuit 1c Plural signal lines 2, 10 Connector 3 Built-in modem 3c, 4a, 6a, 7a, 8a, 8b Plural signal lines 3d, 5a, 5b Single signal line 4 AND gate circuit 5 OR gate circuit 6, 7 RS-232C
Driver 8 RS-232C
Receiver 9 Switch 11 External modem

Claims (1)

(57) [Scope of request for utility model registration] 1. A serial control unit having a first transmission circuit for transmitting a first transmission signal, a first reception circuit for receiving a second transmission signal, and a first control circuit from the first transmission circuit. A second receiving circuit for receiving the transmission signal of
ANDing a built-in modem having a second transmission circuit for transmitting the second transmission signal, and a third transmission signal from the external modem by taking an AND of the second transmission signal and a third transmission signal from an external modem; An AND gate circuit that sends a result to the first receiving circuit; and a logical sum of the second transmission signal and the third transmission signal, and a result of the logical sum is stored in the serial control unit. An OR gate circuit for transmitting the signal to the receiving circuit, a first driver for converting a signal level of the output signal of the AND gate and the OR gate to a signal level of the external modem, and a signal of the first transmission signal. A second driver for converting a level into a signal level of the external modem; and a receiver for converting a third transmission signal from the external modem into a logical signal level and transmitting the logical signal level to the OR gate and the AND gate. When the third from the outer set modem
And a switch for selectively switching transmission of the transmission signal to the receiver or transmission of the transmission signal converted by the first driver to the connector of the external modem. And a function of monitoring, on a connector of the modem, a transmission signal from the external modem, a third transmission signal from the external modem, and a transmission signal from the serial control unit.
Input / output signal switching circuit for S terminal device.