JPS61237540A - Multiplex transmitter - Google Patents

Abstract

PURPOSE:To prevent the same data from being sent duplicatedly from the sender side or from being outputted duplicatedly at the reception side by sending data expressed a parallel n-bit signal as one-frame serial data. CONSTITUTION:A CPU 1 inputs character data expressed in n-bit digital data to a transmitter 2 as parallel data via a data line 11 and the input data is converted into the serial data. Then the CPU 1 inputs a short strobe signal to a start terminal STA via a strobe line 12 and sends the serial data by one frame. Then the serial data by one frame enters a receiver 4 via an optical fiber 3 and converted into parallel data. In this case, the short strobe signal is generated and inputted to a terminal 22 via the strobe line 14. A printer 5 is operated once by using the strobe signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (2) Technical Field The present invention relates to a multiplex transmission device suitable for transmitting printer data and the like.

Conventionally, printer data has been transmitted using a large number of electric wires, as shown in FIG. (: When the PU 3Q generates an n-bit signal and needs to transmit it to the printer 31, electric wires 32 equal to the number of bits are provided in parallel to transmit the parallel signal.

Since the parallel signals are transmitted in parallel, the printer 31 immediately prints the data.

If parallel signals were transmitted in parallel in this way, a large number of electric wires would be required, which is not desirable.

Therefore, it may be possible to use a signal multiplex transmission device.

FIG. 3 is a conceptual diagram showing an example of an optical data link. C.P.
The υ30 and the printer 31 are coupled by a single light beam μ33. To achieve this, it is necessary to provide an optical transmitter 34 that performs parallel/serial conversion and E10 conversion following the CPU 3Q. Further, an optical receiving device 35 that performs O/E conversion and serial/parallel conversion is provided upstream of the printer 31.

B) Prior Art An optical data link module μ that integrates transmission and reception and enables bidirectional optical communication is already commercially available and in use. For example, there is Sumilink-SGRTT (manufactured by Sumiden Electric Industry Co., Ltd.).

This is an optical data link that converts 16 channels of parallel signals into serial signals by time division multiplexing and optically transmits them. It is driven by 5V, and the receiving circuit includes a photodiode PD, an amplification circuit, and a binarization circuit. The serial/l//parallel conversion circuit outputs a 16-bit signal as 16 parallel signals.

The transmitting circuit includes an LED driving section and an LED. A 16-bit serial signal is converted into an optical signal via an LED driver. Further, the 16 channels of para-Vμ input signals are converted into serial signals by the parallel/L//serial μ conversion circuit.

The final output is an open collector output.
Can directly drive relays and lamps.

(2) Problems with the Prior Art Such optical data links were originally intended to correspond to the on/off state of a switch and the energization or de-energization of a load.

The state of the switch does not change constantly, and therefore the transmission output changes little. Since these are the signals to be transmitted, serial/parallel conversion and parallel/serial conversion are automatically repeated.

In the case of a signal such as a switch, there is only on or off, and since this is an amount that can be continued continuously, there is no problem even if parallel/serial conversion etc. are repeated automatically.

I would also like to use the multiplex transmission device for communication between the CPU and the printer. However, that optical data link module is useless. This is because each character in printer data is separated.

FIG. 4 illustrates parallel/serial conversion.

The output signal from the CPU consists of a strobe signal and data bits. If this is time-division multiplexed, data bits will be sampled in sequence.

In the case of the conventional optical transmission module μ, while one character of parallel data is sent out from the CPU, sampling is repeated many times. For example, if the CPU is
When a character is being output, if sampling is repeated m times, m characters A will be transmitted, such as %AAA...A''.

One character is expressed by parallel n-bit signals. Serial data consisting of n bits obtained by converting this data from parallel to serial is called one frame.

One frame may include a start bit, stop bit, parity bit, etc. in addition to data bits.

It is sufficient to make one character correspond to one frame. Excessive sampling is repeated to create a signal of m frames for one character, so 'A'' becomes %AAA...A
“It becomes.

61 Purpose The purpose of the present invention is to provide an optical multiplex transmitter/receiver in which printer data and the like are sampled repeatedly and the same character is not transmitted twice, and one character corresponds to one frame.

(4) Configuration A start terminal STA is provided on the transmitter side, and when a strobe pulse is applied thereto, the transmitter transmits only one frame of serial data. A strobe pulse is output from the CPU for each character.

In this way, only one frame of serial data is sent out for one character on the transmitting device side.

A reception completion pulse terminal DRP is provided on the receiving device side. Each time one frame of serial data is received by the receiving device, the DRP generates a null pulse. The printer thereby receives and prints out the parallel data.

FIG. 1 is a schematic diagram of a multiplex transmission apparatus according to the present invention. This multiplex transmission device performs parallel-to-serial conversion (parallel/serial conversion) on a parallel signal, sends it out as a time-division multiplexed signal, performs serial-to-parallel conversion (serial/parallel conversion) in the receiving section, and converts it into a parallel signal. This is what is output.

The characters of the CPU 1 are printed out by the printer 5, and the optical multiplex transmission device of the present invention is used in the process.

The optical multiplex transmission device includes a transmitting device 2, an optical fiber 3, and a receiving device 4.

One character is represented by n-bit digital data. The CPU outputs this from the n-channel output terminal.
Parallel input is made to the transmitter 2 via the data line 11.

The transmitting device has the following partial functions.

■) Para Vl/Serial w conversion circuit (bl LED drive circuit (CILED (outline of dlsTA terminal) to (c) are also provided in conventional optical transmitter circuits.Here, they are referred to as optical transmitter circuits. is in a broad sense.Although it is sometimes said that only CL is an optical transmitter circuit, here it refers to a circuit that includes Shin) to (dl).

The parallel/serial conversion circuit converts digital data applied to an n-channel data input terminal into n-bit serial data, and is composed of a shift register.

The LED drive circuit amplifies a voltage waveform corresponding to serial data to generate a current and voltage that can drive an LED.

LEDs are electro-optic converting devices that produce a light output that is proportional to the strength of the current. This is installed inside the optical connector.

The optical connector 23 at the end of the optical fiber 3 is connected to this.

Now, the STA terminal is newly added and is used to control the timing of sending out serial data that has been converted from parallel to serial.

When a short stroke pass μ is applied to the STA terminal, the parallel/serial conversion circuit in the transmitting device 2 sends out only one frame of serial data. "One short" means that it is shorter than the time of one frame.

This pulse may be a positive pulse or a negative pulse, but for example, it will be explained as a positive pulse (H level) v).

When a continuous strobe signal longer than one frame (that is, held at H level) is applied to the start terminal STA, serial data continues to be sent out repeatedly during this period. In other words, if we set 5TA=H,
It will perform the same function as a conventional transmitter circuit. Conventional optical multiplex transmission has been optimal for transmitting on/off signals for switches and corresponding loads, but the present invention can also be used for such optical multiplex transmission.

On the other hand, the CPU 1 outputs a short strobe signal from the strobe terminal 21 every time it outputs one character.

The strobe signal is a pulse shorter than one frame and is input to the start terminal STA of the transmitter 2 via the strobe line 12.

When one character is input in parallel to the transmitting device and converted into serial data, a strobe signal is input to the STA terminal, so that the serial data is sent out from the transmitting device.

When transmission of one frame is completed, new character data is input in parallel from the CPU to the parallel/serial conversion circuit. This is immediately converted to serial. A strobe signal is applied to the STA terminal. Serial data is sent for one frame.

In this way, one character becomes one frame of serial data and is sent out. A single character is not repeatedly sampled and sent out.

The serial data transmitted through the optical fiber 3 enters the receiving device 4 from the optical connector 24 .

The receiving device includes the following functions.

(e) Photodiode (f'l Receiving circuit...Includes amplification and binarization circuit (2) Serial I/Para V) conversion circuit) DR
F' terminals (2) to (2) are also provided in conventional receiving devices. The new feature is the addition of a fence.

The photodiode is reverse biased and the optical signal transmitted through the optical fiber is converted into a current signal. The receiving circuit amplifies the weak current signal, compares it with a predetermined threshold, and binarizes it. Since this is a restored six serial μ data transmitted as a digital μ signal, the original signal is extracted by serial/I//variable p conversion.

Parallel data is input to the printer 5 from the output terminal of the n-channel μ through the data line 13.

The reception completion pulse terminal DRP is newly provided. In the receiving circuit 4, a short strobe signal pulse is generated when the reception of one frame of serial data is completed. The strobe signal is input to the strobe terminal 22 of the printer 5 through the strobe line 14 . The moment the strobe pulse is input to the strobe terminal 22, the printer 5 prints out characters corresponding to the parallel data.

One frame worth of serial data is sent to the receiving circuit's serial/I
//When input to the parallel conversion circuit, the DRP terminal generates a short strobe pulse once. The strobe pulse causes the printer to perform a print ↑ operation once. Only one character is printed per frame. Therefore, the same character will not be printed twice.

ψ) Effects (1) Signals are multiplexed and transmitted, so many electric wires are not required.

(2) It is possible to send binary codes such as switch signals such as on and off, and it is also possible to send signals such as printer data. The difference between the two signals can be arbitrarily given by the length of the pulse applied to the STA terminal on the transmitting side and the DRP terminal on the receiving side.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a multiplex transmission apparatus according to the present invention. FIG. 2 is a configuration diagram of a conventional transmission device that transmits and receives 1-bit signals in parallel using a large number of electric wires. FIG. 8 is a conceptual diagram of a multiplex transmission device. FIG. 4 is a waveform diagram for explaining that if sampling is repeated many times while one character is being output, the same character will be repeatedly output. 1... CPU 2... Transmitting device 3... Optical fiber 4... Receiving device 5... Printer 8... STA terminal 9...DRP terminal Inventor Satoshi Sugimoto
Yoshinobu Hayashi

Claims (1)

[Claims] A transmitter converts a parallel signal into a time division multiplexed signal and sends it out again as an optical signal, an optical fiber transmits the optical multiplexed transmission signal, and converts the optical signal back into an electrical signal and converts it into a serial/parallel signal. , consists of a receiving device that outputs as a parallel signal, the transmitting device has an STA terminal that samples the parallel signal and controls one frame cycle for serial transmission, and the receiving device completes reception when outputting the parallel signal after receiving one frame cycle. It has a DRP terminal that outputs pulses, and if a pulse shorter than one frame is applied to the STA terminal, the transmitter will serially transmit only one frame, and if a level signal is continuously applied to the STA terminal, the frame cycle of sampling and serial transmission will continue. The multiplex transmission device is characterized in that the receiving device outputs a reception completion pulse from the DRP terminal after receiving the frame in any case.