JPS5979657A - Method for transmitting data - Google Patents

Abstract

PURPOSE:To attain communication almost equivalent to full duplex communication by transmitting data from a terminal station to a control station in each period from the trailing edge to the leading edge of a repeating pulse sent from the control station, in the data transmission method executing half duplex communication. CONSTITUTION:In accordance with a start signal ST, an address signal A and a command signal C applied to a terminal T1 of the control station 1, a transistor TR1 is turned on/off and sends a signal to a terminal station 2. Receiving the signal through a driver DR1, the terminal station 2 executes processing on the basis of the command signal C if the address A is terminated to the self- station. In addition, the terminal station 2 forms a synchronizing signal from the trailing edge of the repeating pulse signal R sent from the control station 1 and transmits the data of the processed result and the synchronizing signal from a terminal 4 to the control station 1 through a driver DR2 and a constant current circuit CC. In accordance with the on/off of a TR2, a light emitting element LE is also turned on/off and the operation of the LE is received by a receiving element PS and taken out from a terminal T2 through an inverter IN.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data transmission method, particularly a contention method (where the transmitting side is Data is sent and received using the polling method (communication is performed by checking whether or not there is data to be sent to the other party) or by polling. This invention relates to a method for returning information from a terminal station in response to a call from a control station in five cases.

FIG. 1 is a schematic diagram showing a general data transmission system, and FIG. 2 is an explanatory diagram for explaining a data communication method.

That is, as a method of data communication between the master station 1 and the slave station 2 as shown in Fig. 1, so-called half-duplex communication is used in which signals or information as shown in Fig. 2B) and Naka) are sent alternately. method is known. In addition, 3 in Fig. 1 indicates the transmission line, and Fig. 2 (a) shows the transmission signal sent from the master station to the slave station, and the same (b) shows the return signal sent from the slave station to the master station. It is something.

Finally, the master station 1 selects the slave station 2 based on the addressee, and then sends command information C and the like. On the other hand, slave station 2 reads the transmission information from master station 1 in reception mode, and if the addresses match, it switches to transmission mode, and master station 1
own station address A, command C and data D
etc. to perform data communication. In addition, Figure 2 (a)
, ST is a start signal and SP is a stop signal. However, this method has the drawback that the number of parts on the slave station side increases, which increases the size of the slave station circuit, leading to an increase in cost, and furthermore, the transmission of the slave station 2.

It also has the disadvantage that it requires switching the reception mode, resulting in a slow response. Particularly in cases where there are a large number of slave stations and the content of data to be transmitted is limited to digital or analog amounts, it is even more difficult to adopt the method described above from a cost perspective. It's hard to say it's a good idea.

Furthermore, as an example of a method for performing bidirectional communication between two stations, there is an FS modulation method using a frequency-modulated signal fO*fl as shown in FIG. However, since this method requires a qFS modulation circuit, a filter circuit, etc., it has the disadvantage that the circuit configuration becomes complicated.

The present invention has been made in view of the above points, and it is an object of the present invention to realize at low cost a data transmission system which is equivalent to a full-duplex system although it is a half-duplex system.

Its feature is that in a data transmission system that performs half-duplex communication between a control station and a terminal station, the control station selects a desired terminal station and then sends out at least a series of repeated pulse signals. The receiving terminal station transmits the specified data to the control station using each period from the falling edge to the rising edge of the signal. That's the point.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a schematic diagram showing an embodiment of the present invention, and FIG. 4 is an explanatory diagram showing transmission information sent from the master station side. In addition,
FIG. 4(A) shows the transmission information sent from the master station to the slave station side, and also shows an enlarged part of FIG. 4(A).

In FIG. 3, 1 is a control (parent) station, 2 is a terminal (child) station, and 3 is a transmission line. The control station 1 also has transistors 'l, 1. The terminal station 2 is composed of drivers DR, 1, DR, 2, constant current circuit CC, and the like. A signal corresponding to the information to be transmitted is applied to the terminal T1, and therefore, the transistor TR1 is turned on and off according to the transmitted information, but the transistors TR and 2 are at least turned off when the transistor TR1 is on, and the terminal station 2 It is constructed so as to be operated by electric current from.

On the other hand, the terminal station 2 receives the transmission information from the control station 1 via the driver DRI, while the terminal T4 and the driver DR2
and transmits predetermined information to the control station 1 via the constant current circuit CC. Note that CN is a control signal given to the drivers DJ and DR2.

Here, when the start signal ST, address signal A, and command signal C are applied to the terminal T1 at the control station 1 as shown in FIG. 4(a), the transistor TR1 is turned on and off according to these signals. , a series of information as described above is given to the terminal T3 of the terminal station 2. The terminal station 2 first decodes the address signal A, and if it determines that it is addressed to itself, then executes a predetermined process based on the command signal sent. Furthermore, the control station 1 continues to send a series of repetitive pulse signals, for example, a fourth pulse signal.
Since the R, Z pulse signal ratio as shown in Figure (b) is sent, the terminal station 2 generates a synchronization signal from the falling edge of the IZ pulse signal using a counter, decoder, etc.
This synchronization signal and data based on the previous processing result are applied to the terminal T4 via a predetermined gate, and transmitted to the control station 1 via the driver DR2 and constant current circuit CC1z. The control station 1 receives the data returned from the terminal station 2 via the transistor TR2. Transistor TR2 turns on and off depending on the presence or absence of data, so
The light emitting element LH is also turned on and off in the same way, and this is received by the light receiving element PS and sent to the terminal T2 via the inverter I'N.
It is taken out from. Note that the transistor TR2 [
Since the operation is opposite to that of TR1, information is transmitted from the terminal station 2 by filling in the spaces between the RZ pulses.

As described above, according to the present invention, by transmitting at least a series of repetitive pulses from the control station side, the terminal station side can use the pulse signal as a synchronization signal, and Since data can be transmitted by filling in the pulse signal, the terminal station does not need a clock source, and there is no need to switch between reception and transmission modes, so the access time to the terminal station is shortened. Further, full-duplex communication has the advantage that communication equivalent to y is possible. Furthermore, since data can be transmitted by filling in the gaps between repeated pulses sent from the control, signal lines can be shared between upstream and downstream, and the number of expensive signal lines can therefore be reduced. It has advantages.

In addition, in the above explanation, the Z pulse is sent after the address, command signal, etc., and is returned by filling in the space between them, but in the case of one-to-one communication, that is, when there is no need to send an address signal, It is possible to send back information from the terminal station using the zero section of all the information (repetitive pulse signal) transmitted from the control station.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a general data transmission system, Fig. 2 is an explanatory diagram for explaining a data communication method, Fig. 3 is a schematic diagram showing an embodiment of the present invention, and Fig. 4 is a schematic diagram showing a data communication method. FIG. 3 is an explanatory diagram showing transmission information transmitted from the master station side. Code explanation 1... Control (parent) station, 2... Terminal (child) station, 3... Transmission line, TR, 1, TR2.
-... Transistor, LB... Light emitting element, PS... Light receiving element, IN... Inverter, DRl, DR2... Driver, CC...・
...Constant current circuit, T1 to T4...Terminal representative Patent attorney Akio Namiki Patent attorney Kiyoshi Matsuzaki Figure 1 Figure 2 Calculation Figure 4

Claims (1)

[Claims] In a data transmission system that performs half-duplex communication between a control station and at least one terminal station connected via a transmission line, the control station selects a desired terminal station and then transmits at least a series of repeated cycles. A data transmission method characterized in that a return pulse signal is sent out, and a terminal station that receives the signal transmits predetermined data to a control station using each period from the falling edge to the rising edge of the signal.