JPS6261183B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a communication control device in a data processing device, and in particular to transmission/reception timing of a DC communication circuit using an independent synchronization method (including a character synchronization method and a bit synchronization method). This invention relates to signal supply means.

[Conventional technology]

Conventionally, a communication control device that connects a plurality of terminal devices, etc. to a central processing unit uses a modem to connect the terminal devices, and since the modem is equipped with a timing signal supply means, the timing signal is can be used to determine the timing of data transmission and reception. However, when this type of communication control device is directly connected to the other device via a DC transmission line without using a modulation/demodulation device, etc., in order to synchronize the transmission and reception, as shown in Figure 1a, Communication control device
An external additional circuit such as an oscillator is connected between the line connection adapter LA of the CCU and the other device, and its oscillation output is sent to the line connection adapter via a timing line.
It was used for sending and receiving timing by supplying it to the LA and the other party. Synchronization is a necessary condition, especially when used in time division multiplexed circuits.

[Problem that the invention seeks to solve]

Although the configuration described above can be connected without making any changes to the line connection adapter or the like, it has the disadvantage that the amount of hardware increases due to the provision of an external additional circuit, making the device larger. In addition, when changing the communication speed, it is necessary to replace an external additional circuit or manually change it using a switch, etc., so there is a risk of incorrect settings and connection errors.

An object of the present invention is to provide a communication control device that has a built-in timing circuit without using an external additional circuit, can change the communication speed, switch internal and external timing signals, etc. freely and without error, and can be miniaturized. Our goal is to provide the following.

[Means for solving problems]

A communication control device of the present invention is a communication control device that connects a plurality of lines to a central processing unit, and includes a timing signal generator that generates a plurality of transmission/reception timing signals having different communication speeds, and a timing signal generator that generates a plurality of transmission/reception timing signals having different communication speeds. a frequency selection circuit that selectively selects and outputs an output signal; and a transmission/reception timing signal switching circuit that selectively outputs an externally input transmission/reception timing signal or an output signal of the frequency selection circuit. , a control word register that stores a control word in advance and controls selection and switching of the frequency selection circuit and the transmission/reception timing signal switching circuit in accordance with the input control word.

[Effect]

The communication control device is the other party's device (e.g. terminal device)
When connected via a communication line, a modem is naturally involved, and a timing signal supplied from the modem is used to operate the transmitting circuit and the receiving circuit.

When connecting directly to the other party's device without going through a communication line, that is, when connecting without going through a modulator/demodulator, no timing signals arrive from outside. At this time, it uses its own timing signal, selects a timing signal according to the transmission speed, and performs transmission and reception operations.

Note that this timing signal is also sent to the other party's device as a timing signal, so that the other party's device appears to be connected to a modem and modem, and the timing can be determined by the other party's device.

〔Example〕

FIG. 2 is a block diagram showing one embodiment of the present invention.

In this embodiment, a case will be described in which a plurality of terminal devices are connected to a central processing unit as counterpart devices.

In this case, in the case of a normal connection method in which terminal devices are connected via a modem or the like, timing signals RT and ST supplied from the modem or the like are used. Also, for example, if a terminal device is located near a communication control device and the terminal device is directly connected to the communication control device without using a modulation/demodulation device, the timing signal from the modulation/demodulation device, etc. cannot be used. , using timing signals from its own device. This timing signal from the own device is also supplied to the other party's terminal device as timing signals RT' and ST', so the other party's device treats it in the same way as in the case of a normal connection method in which a modem device, etc. is connected. be able to.

This embodiment includes a receiving circuit 1 that receives data, performs serial-to-parallel conversion, and transfers it to the central processing unit, a transmitting circuit 2 that receives data from the central processing unit, performs parallel-to-serial conversion, and transmits the data, and a standard An oscillation circuit 8 that oscillates a frequency, a frequency division circuit 7 that outputs a timing group suitable for various communication speeds from the output of the oscillation circuit 8, and a frequency selection circuit that selects and outputs a desired timing from the output signal of the frequency division circuit 7. 6, and an RT switching circuit 3 that selectively selects the output signal of the frequency selection circuit 6 or the reception timing signal RT from the outside and supplies it to the reception circuit 1.
and an ST switching circuit 4 which selectively selects the output signal of the frequency selection circuit 6 or a transmission timing signal ST from the outside and supplies it to the transmission circuit 2, and the control word sent from the central processing unit. A control word register 5 is provided for controlling the switching of the RT switching circuit 3 and the ST switching circuit 4 as well as the switching of the frequency selection circuit 6. Converts the signal level to an external signal and sends the reception timing signal RT' and transmission timing signal ST' to the other party, and similarly sends the output signal of the transmission circuit 2 as the transmission signal SD via the transmission level conversion circuit (driver) 10. , the receive timing signal sent from the other party
RT, transmit timing signal ST and receive signal RD
are connected to the RT switching circuit 3, the ST switching circuit 4, and the receiving circuit 1 via a reception level conversion circuit (receiver) 9, respectively.

In the control word register 5, a control word having a structure as shown in FIG. 3 is given and stored, for example, from the central processing unit at the time of initial setting of the communication control device.

Bit position “2” (instruction bit) shown in Figure 3
DIRCT), use the output signal of the frequency selection circuit 6, or use the external timing signals RT, ST.
A selection signal indicating whether to use the data is determined corresponding to the logic state of "1" or "0". This is the reception level at the RT switching circuit 3 and ST switching circuit 4 when the timing signals RT and ST transmitted from the other party are used as timing signals by connecting a modem or the like when the logic state is "0". This is used to select the timing signals RT and ST signals from the conversion circuit, and is kept in this logic state in the case of normal connection.

Also, when the instruction bit DIRCT selects 1 and the logic state of bit positions "6" and "7" (that is, the instruction field BRT) is "00", the timing signal of the communication speed of 2400 baud, the logic state "01".
At 4800 baud timing signal, logic state “10”
9600 baud at logic state "11" to select a 48 kilobaud timing signal. The control word register 5 uses the previously stored contents and the control word sent from the central processing unit.
Controls switching of RT and ST switching circuits 3 and 4 and frequency switching selection circuit 6.

The communication control device configured as described above can freely perform
You can set the communication speed and freely select whether to use a built-in timing signal or a timing signal sent from the other party. Furthermore, the output signal of the frequency selection circuit 6 is transmitted via the driver 10 to a transmission/reception timing signal.
The signals are supplied to the other device as ST' and RT'. The partner device treats these timing signals RT', ST' as being equivalent to the timing signals RT, ST that would be supplied by a modulator/demodulator or the like in the case of a normal connection method, and can thereby achieve synchronization.

Therefore, from the other party's side, it appears to be the same as if a modulation/demodulation device or the like is connected, and processing can be performed.

Note that although the oscillator 8 and the frequency division circuit 7 are used in common for each line, other parts are provided for each line. Further, common control portions similar to those of the prior art are omitted in FIG. That is, the overall structure is as shown in FIG. 1b, and no external additional circuit is required as in the conventional case. Further, the communication control device and the other party device are connected by a direct connection cable as shown in FIG. Dotted lines in FIG. 4 indicate core wires for transmitting other necessary control signals such as request/ready signal RS, data set ready signal DR, etc.

〔Effect of the invention〕

As described above, in the present invention, timing signals of various communication speeds are generated, and the selection of the communication speed and switching between the use of internal timing signals and the use of external timing signals are performed using control words from the central processing unit. Since it is configured to perform freely and automatically, there is no need to add an external additional circuit as in the past. Therefore, it is possible to downsize the device, and there is no risk of erroneous connections, switching errors, etc. Further, since it is easy to change the communication speed, etc., there is an advantage that communication control can be performed with great flexibility.

[Brief explanation of the drawing]

FIG. 1a is a diagram showing an example in which an external additional circuit is added to a conventional communication control device. FIG. 1b is an overall configuration diagram showing an example of the present invention. FIG. 2 is a diagram showing an embodiment of the present invention. FIG. 3 is a diagram showing an example of a control word structure used in the present invention. FIG. 4 is a diagram showing an example of a connection cable between a communication control device and a partner device. DESCRIPTION OF SYMBOLS 1... Receiving circuit, 2... Transmitting circuit, 3... Reception timing signal switching circuit, 4... Transmission timing signal switching circuit, 5... Control word register, 6... Frequency selection circuit, 7... Frequency division circuit , 8...Oscillator, RD...Reception data signal, SD...Transmission data signal, RT, RT'...Reception timing signal,
ST, ST′...Transmission timing signal.

Claims (1)

[Claims] 1. A communication control device that connects a plurality of lines to a central processing unit, comprising: timing signal generators 7 and 8 that generate a plurality of transmission/reception timing signals having different communication speeds; A frequency selection circuit 6 that selectively selects and outputs an output signal, and a transmission/reception timing signal switching circuit that selectively outputs a transmission/reception timing signal input from the outside or an output signal of the frequency selection circuit. 3,4
and a control word register 5 that stores a control word in advance and controls selection and switching of the frequency selection circuit and the transmission/reception timing signal switching circuit in response to the input control word. Control device.