JP3124888B2 - Optical data communication equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical data communication apparatus used when a plurality of computers (workstations) are connected by optical communication and operated while exchanging data with each other. The present invention relates to an optical data communication apparatus provided with transmission control means for avoiding interference with other devices when starting transmission of optical data.

[0002]

2. Description of the Related Art FIG. 5 shows an example of this type of conventional optical data communication apparatus. For example, when four workstations WS1 to WS4 are operated by data link as described above, each of them is operated. Workstations WS1 to WS
The optical data communication devices 90A to 90D are connected to 4 and transmit required data in the form of packets or the like by infrared rays.

At this time, if a plurality of optical data communication devices, such as the optical data communication device 90A and the optical data communication device 90B, transmit at the same time, the packet is destroyed due to interference. 90D has P-Presistent CSMA in order to avoid interference.
(Carrier Sense Multiple Access).

FIG. 6 is a flow chart showing the operation of the above-described control method.
(A to D) confirm the presence or absence of a carrier from another device before starting transmission (S91), and if there is, loop and wait until the carrier from the other device disappears. Further, when the carrier does not exist or the carrier disappears, the optical data communication device 90 generates the random number R by the internally provided random number generator without immediately starting the transmission (S92).

Thereafter, the random number R is compared with the system constant C held in each of the optical data communication devices 90 (S93). If R <C, the optical data communication device 90 starts transmission. (S94) If R ≧ C, the process loops to carrier detection again, and the process from the beginning is repeated.

In this way, for example, when no carrier exists, two optical data communication apparatuses 90
When a transmission request is made, the both cannot detect the carrier, and therefore, it is possible to prevent an accident in which both start transmission at the same time and the packet is destroyed.

The optical data communication device 90 (A to D)
Depending on the installation state of the optical data communication device 90, carrier detection may not be possible between a specific pair of optical data communication devices 90 due to, for example, the directional characteristics of the transmission unit. In such a case, the random number R and the system constant C With the configuration for determining whether transmission is possible or not by comparison with the above, it is possible to similarly reduce the probability of packet destruction.

[0008]

Here, in the above-described conventional optical data communication apparatus 90, whether or not the operation can be performed smoothly depends on the value of the system constant C held by each optical data communication apparatus 90. It depends. However, since the setting of the system constant C is performed by a system administrator or the like, the optimum value is not always set due to, for example, a lack of experience, causing packet destruction or data loss. There are problems such as a decrease in transmission efficiency.

The system constant C changes its optimum value by changing the number of installations or changing the installation location as described above. The setting must be redone, and the operation becomes complicated, and the solution of these points has been an issue.

[0010]

According to the present invention, there is provided an optical data communication apparatus for transmitting and receiving data to and from a plurality of connection partners by using light such as infrared light. The data communication device is provided with a light intensity measurement circuit for measuring the light intensity of the optical signal of the connection partner, and sets a system constant for each connection partner in inverse proportion to the light intensity of all the connection partners measured in advance. This problem is solved by providing an optical data communication apparatus characterized in that the transmission and reception are performed in the connection order according to the system constant.

[0011]

Next, the present invention will be described in detail based on an embodiment shown in the drawings. An optical data communication device according to the present invention is denoted by reference numeral 1 in FIG.
Includes a light emitting module 11 including a light emitting element such as an infrared light emitting diode and a driving circuit, and a light receiving module 1 including a light receiving element such as a photodiode and a preamplifier.
2 is provided to transmit and receive optical data in a packet state, as in the conventional example.

The optical data communication device 1 is provided with a microprocessor 13 (hereinafter abbreviated as MPU 13). When a transmission request is generated from a workstation WS connected to the optical data communication device 1, It is also the same as the conventional example that the light receiving module 12 is made to detect the carrier and then to transmit according to the procedure described in the conventional example (see FIG. 6).

In the drawing, reference numeral 14 denotes an amplifier for amplifying a signal from the light receiving module 12 to a level which can be processed, and reference numeral 15 denotes an amplifier for increasing the signal level of the amplifier 1.
4 is a demodulation circuit for demodulating the signal from the workstation WS so as to be suitable for input to the workstation WS, and a modulator circuit 16 for modulating the output from the workstation WS so as to be suitable for transmission from the light emitting module 11. is there.

Here, in the present invention, the optical data communication apparatus 1 is provided with a light intensity measuring circuit 17, and more specifically, is connected to the output of the amplifier 14 as an A / D conversion circuit. The MPU 13 converts the intensity of the optical signal received by the MPU 13 into a digital value, and the MPU 13 can take in the digital signal. The MPU 13 is provided with a setting switch 13a as necessary.

FIG. 2 is a flowchart showing the operation of the optical data communication apparatus 1 having the above-described configuration. According to the present invention, the optical data communication apparatus 1 has a communication cycle S20 similar to the conventional example and a system constant. A setting cycle S30 for automatically setting is provided. Usually, a communication cycle S30 is performed according to a transmission request from the workstation WS.
20 is activated, while the setting cycle S30
Is operated only when a request from a system administrator or the like is made, for example, when the setting switch 13a is operated.

FIG. 3 shows an example of the arrangement of the optical data communication devices 1 when the setting cycle S30 is started. In this case, three optical data communication devices 1 are arranged.
A, 1B, and 1C communicate with each other, and the distance L1 between the optical data communication device 1A and the optical data communication device 1B is determined by the optical data communication device 1B and the optical data communication device 1C.
The distance L2 between the optical data communication device 1B and the optical data communication device 1C is shorter than the distance L3 between the optical data communication device 1A and the optical data communication device 1C. Assume it is short.

Under the above conditions, assuming that the optical data communication device 1B and the optical data communication device 1C simultaneously start transmission to the optical data communication device 1A,
The distance L3 between A-1C is the optical data communication apparatus 1A-1B
The optical data communication device 1
The optical data communication apparatus 1B has a large amount of attenuation of the packet on the C side.
The packet is destroyed by being masked by the packet on the side.

Therefore, if the system constants set in the optical data communication device 1B and the system constants set in the optical data communication device 1C are the same in the above state, both of them transmit simultaneously. The probability of starting is the same,
As a result, the rate of destruction of the packet on the optical data communication device 1C side increases, that is, the optical data communication device 1A-1
The communication efficiency between C decreases.

Based on this principle, the setting cycle S3
0 is an operation, for example, the setting switch 13a
Is operated, and the setting cycle S30 is activated, the setting cycle S30 makes a transmission request (S31) to the optical data communication device 1B, for example, and transmits a packet having an appropriate content (S32).

The packet from the optical data communication apparatus 1B is received by the optical data communication apparatus 1A or 1A and 1C (S33), and the light intensity measuring circuit 17 provided for each is received.
The analog value is converted to a digital value by (S34) and MP
A value that can be read by U13 is taken into MPU13.

At this time, if the numerical value obtained by the light intensity measuring circuit 17 of the optical data communication device 1A is Ab and the numerical value similarly obtained by the optical data communication device 1C is Cb, respectively. MPU 13 as a system constant for the optical data communication device 1B is a numerical value inversely proportional to the numerical values Ab and Cb, that is, the optical data communication device 1A has K / Ab,
The optical data communication device 1C sets and stores K / Cb as a system constant (S35). Here, K is an arbitrary constant.

Similarly, if a transmission request is made to the optical data communication device 1C (S36), a system constant for the optical data communication device 1C is obtained for the optical data communication device 1A and the optical data communication device 1B. At this time, if the attenuation is determined simply by the distances L1 to L3 between transmission and reception under the same conditions, the optical data communication apparatuses 1A to 1C have system constants for them. .

In actual implementation, the efficiency, sensitivity, light receiving angle,
According to various conditions such as the direction, the reception intensity is the same between when transmitting from the optical data communication device 1A to the optical data communication device 1B and when transmitting from the optical data communication device 1B to the optical data communication device 1A, for example. Therefore, it is preferable that the reciprocal of the reception strength of the other party when the user transmits data is held as a system constant for the other party.

Since the system constant set as described above is adopted in the communication cycle S20, the system constant having a higher probability is held for a partner with lower reception sensitivity. The transmission is performed with a higher probability as the transmission is performed to a lower partner, thereby improving the communication efficiency by reducing the masking of the transmission performed by the partner having higher reception sensitivity.

Here, the most important thing is that the optical data communication apparatus 1 automatically generates an optimum system constant for the number of installations or the arrangement, etc. by adopting the configuration of the present invention. For example, when the number of installations increases or decreases or the installation location changes, the setting cycle S20
, The optimum state can be quickly obtained without any experience or the like.

In the embodiment described above, the optical data communication apparatus 1 is provided with the setting switch 13a and the setting cycle S30. For example, when an extension or relocation is performed, the setting cycle S30 is activated to start a new system. Although the constant is set, the setting switch 13a is not always required in the present invention.

FIG. 4 shows the setting switch 13.
5 is a flowchart showing a communication cycle S40 when a is not provided, and in this embodiment, the optical data communication device 1
Is to set a system constant using a normal communication, and to revise the system constant when a change occurs in the situation.

In order to achieve this purpose, in the communication cycle S40 of this embodiment, there is a connection request from the other party, and when an optical signal is transmitted, it is received by the optical intensity measuring circuit 17 (S41). Converts intensity to digital quantity (S4
2) and input it to the MPU 13, and the MPU 13 sets the system constant for the other party (S43), writes it in a memory or the like (S44) and holds it.
In the same communication cycle S20 as in the previous embodiment, the system constants are read and used.

By doing so, the system constants for all the communication partners are set by several communications. However, if the status changes due to relocation or the like at this time, The revision is made immediately in the communication cycle S40. Therefore, the user does not need to know anything about the system constant and can use the system constant without consideration.

However, in the case of this embodiment, the communication state may be changed due to a temporary cause such as shielding by a moving object such as a human body. Unless a process for appropriately lowering the setting sensitivity is performed, such as changing when it is obtained continuously, unnecessary confusion may be caused.

[0031]

As described above, according to the present invention, the optical data communication apparatus is provided with a light intensity measuring circuit for measuring the light intensity of the optical signal of the connection partner, and all of the previously measured connection partners are measured. By setting and holding a system constant for each connection partner in inverse proportion to the light intensity, the optical data communication device performs transmission and reception in the connection order according to the system constant.
As a system constant that improves communication efficiency by making it inversely proportional to the reception intensity can be automatically set, for example, increase and decrease of the number of units, simplifying the work of setting system constants required for each relocation, eliminating the need for experienced people, This is extremely advantageous in simplifying the operation of this type of optical data communication device.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of an optical data communication device according to the present invention.

FIG. 2 is a flowchart showing the operation of the same embodiment.

FIG. 3 is an explanatory diagram showing a state when a system constant is set.

FIG. 4 is a flowchart showing another embodiment of the optical data communication apparatus according to the present invention.

FIG. 5 is an explanatory view showing an installation state of a conventional example.

FIG. 6 is a flowchart showing the operation of the same conventional example.

[Explanation of symbols]

 1, 1A, 1B, 1C Optical data communication device 11 Light emitting module 12 Light receiving module 13 Microprocessor (MPU) 13a Setting switch 14 Amplifier 15 Demodulation circuit 16 Modulation circuit 17: Light intensity measurement circuit S20, S40: Communication cycle S30: Setting cycle WS: Workstation

Claims (1)

(57) [Claims] 1. An optical data communication device for transmitting and receiving data to and from a plurality of connection partners by light such as infrared light, wherein the optical data communication device is provided with a light intensity measurement circuit for measuring the light intensity of an optical signal of the connection partner. Optical data communication, wherein a system constant for each connection partner is set and held in inverse proportion to the light intensity of all the connection partners measured in advance, and transmission and reception are performed in the connection order according to the system constant. apparatus.