JPH0443458B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a communication network that connects a plurality of computer systems via transmission and reception communication lines so that the computer systems communicate with each other. More specifically, the present invention relates to a communication control device for a computer system used in a communication network.

[Conventional technology]

As shown in Figure 1, this type of communication network consists of a plurality of computer systems ₁₁ to _1o connected to each other in a loop using communication lines 2 on the sending and receiving sides, each connected to a different partner. There are devices that configure a measurement control system by sequentially connecting them.

Each of the computer systems 1 ₁ to 1 _o has a communication control device 3 that sends out a transmission signal to the communication line 2 and inputs a reception signal from the communication line 2 .

FIG. 3 shows a block diagram of a conventional communication control device 3 installed in each of the computer systems 1 ₁ to 1 _o .

As shown in FIG. 3, the communication control device 3 includes a communication control circuit section 4, a transmitting circuit section 6, a receiving circuit section 8, and the like. The communication control circuit section 4 has a function of communicating with the computer side of its own station via an interface signal 9 and controlling transmission and reception on the communication line 2 side.

That is, the communication control circuit section 4 receives the transmission command and transmission data from the computer of its own station via the interface signal 9, and transmits the transmission signal 10 converted into a predetermined timing and format by the communication control circuit section 4. Output. The transmission signal 10 is converted into a predetermined output format by the transmission circuit section 6, and sent to the receiving side of the computer system of another station via the communication line 2 on the transmitting side.

When performing this type of communication, an address is attached to the transmitted signal.

On the other hand, the received signal 12 from the communication line 2 on the receiving side
is input to the receiving circuit section 8 via the photocoupler 7. If this signal is a corresponding address, it is converted into a predetermined input format by the reception circuit section 8, converted into a predetermined timing and format by the communication control circuit section 4, and sent to the computer via an interface signal 9 to report reception and receive the signal. Data is sent. If the received signal is not at the corresponding address, the communication control circuit section 4 of the computer system on the receiving side
transfers the signal to the next stage computer system via its transmission circuit section.

The communication control circuit section 4, the transmitting circuit section 6, the photocoupler 7, and the receiving circuit section 8 share power supplies V1 and G1 (G is ground).

The photocoupler 7 is connected to the communication control circuit section 4, which is the center of the communication control system, from which external noise enters via the communication line 2.
It has the function of electrically insulating the communication line 2 and the power supply of the communication control circuit section 4 against so-called noise, which prevents it from affecting the drive power supplies V1 and G1, thereby preventing the system from being disturbed. It has a function. Note that related systems of this type include, for example, Japanese Journal of Clinical Laboratory Automation, JJCLAJOL 6, No. 1 (JANUARY,
(1981) Standard Guidelines for Interfaces between Analytical Instruments and Computers, which are described in a separate volume.

[Problem to be solved by the invention]

As mentioned above, techniques have been known for minimizing the influence of external noise on computer systems and various units by using photocouplers, but these techniques do not satisfy all requirements.

For example, in the prior art illustrated in FIG. 3, the receiving circuit section 8
A photocoupler 7 was installed in the front stage. but,
Since the communication line 2 on the transmitting side and the drive power supply V1 of the transmitting circuit section 6 are not electrically insulated from the communication control circuit section 4, the transmitting system is wired over a long distance to the destination computer system without being insulated. Become. Therefore, there was a problem in that the driving power supplies V1, G1 and eventually the communication control circuit section 1 were easily affected by external noise transmitted to the communication line 2 on the receiving side via the transmitting circuit section 6.

The influence of this noise is due to the communication line load condition [R
(resistance), X _C (capacitive reactance), and X _L (inductive reactance)], and the longer the communication line, the larger it becomes.

Also, as in the communication network disclosed in Japanese Patent Application Laid-Open No. 189351/1983, a photocoupler is used on both the transmitting side and the receiving side, and the driving power source V _B is shared between them.
There is also a method of electrically insulating the drive power supply V _B from the power supply on the communication control circuit side.

In this way, the communication line and the power supply for the communication control circuit section are electrically separated, and the power supply for the communication control circuit section is not affected by noise, which prevents any trouble from occurring to the communication control circuit section. do not have. However, in this case, the communication line between the sending side and the communicating side is common (bus), so it cannot be applied to a loop-type communication network where the communication lines for the sending side and receiving side are separate, as described above. I can't.

In addition, in the case of a bus-based communication line, each unit (connected to the network) shares one communication line, so depending on the type of noise, multiple connected units may absorb noise at the same time. In such cases, the burden of dealing with errors will be high.

The present invention has been made in view of the above points, and its purpose is to significantly improve noise resistance even in a computer system used in a loop type communication network, and to reduce the burden of noise error processing, thereby improving system performance. An object of the present invention is to provide a communication control device that can improve operating efficiency.

[Means to solve the problem]

The gist of the present invention will be explained with reference to the reference numerals of the embodiment shown in FIG.

The present invention is a communication network system in which a plurality of computer systems ₁₁ to _1o are sequentially connected in a loop using communication lines 2 on the sending and receiving sides, each connected to a different partner. The communication control device 3 of each computer system 1 ₁ to 1 _o used for the work includes a communication control circuit section 4 that performs communication with the computer side of its own station via an interface signal 9 and controls transmission and reception on the communication line 2 side.
, a transmitting circuit section 6 that sends out the transmission signal from the communication control circuit section 4 to the communication line 2 on the transmitting side, and a receiving circuit section that inputs the received signal from the communication line 2 on the receiving side to the communication control circuit section 4. 8, and a transmitting photocoupler 5 is connected between the communication control circuit section 4 and the transmitting circuit section 6, a receiving photocoupler 7 is provided at the front stage of the receiving circuit section 8, and the communication control circuit section 4 and the receiving circuit section 8 are connected to each other. Photocoupler 7 and receiving circuit section 8
The driving power supplies V1, G1 and the driving power supplies V2, G2 of the transmitting photocoupler 5 and the transmitting circuit section 6 are provided separately, and these driving power supplies V1, G1, V2, G
The two were electrically separated.

[Effect]

With such a configuration, the communication control circuit section 4
The transmission signal outputted from the transmitter is sent to the transmission side communication line 2 via the transmission side photocoupler 5 and the transmission circuit section 6. A received signal from the communication line 2 on the receiving side is input to the communication control circuit section 4 via the receiving side photocoupler 7 and the receiving circuit section 8 .

The present invention also provides the use of a transmitting photocoupler 5 and a receiving photocoupler 7, and drive power sources V1 and G1 for the communication control circuit section 4, receiving photocoupler 7, and receiving circuit section 8, and the use of the transmitting photocoupler 5 and the transmitting photocoupler 7. Drive power supplies V2 and G2 for the circuit section 6 are provided separately, and these drive power supplies V1, G1, and V
2. By electrically separating G2 from each other, noise in the communication line 2 can be suppressed by the power supply line of the communication control circuit 4, the communication line 2 on the transmitting side, and the communication line 2 on the receiving side. They can be electrically isolated from each other.

Therefore, even if external noise is applied to the communication line 2 on either the receiving side or the transmitting side, it will not have a negative effect on the power supplies V1 and G1 of the communication control circuit section 4, and will not affect the central part of the communication control system and ultimately the computer system. Prevent any problems from occurring. Note that the noise transmitted to the transmission side communication line 2 affects the power supplies V2 and G2, but these power supplies V2 and G2 simply function as drive power supplies for transmission and do not affect the communication control circuit section 4. This will not cause any trouble to the communication control circuit section 4 and, by extension, to the computer system.

Further, although the noise does not affect the power supply system of the communication control circuit section 4, it is taken in as an error signal on the receiving side. In this case, the receiving circuit section 8
Error handling is performed by In this type of loop-type communication network, the communication lines between each computer system are independent and are not bused, so that noise is not introduced into the communication processing systems of multiple computer systems at the same time. As a result, the reception signal (error signal) caused by noise can be processed by the reception system of the computer system in the communication line section where the noise is present, reducing the burden of error signal processing.

〔Example〕

Embodiments of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 2 is a block diagram showing a communication control device according to an embodiment of the present invention, which is installed in each computer system 1 ₁ to 1 _o used in a loop communication network as shown in FIG.

The communication control device 3 of this embodiment includes a communication control circuit section 4, a transmitting photocoupler 5, a transmitting circuit section 6, a receiving photocoupler 7, a receiving circuit section 8, and the like.

Of these, the communication control circuit section 4, the transmission circuit section 6,
The functions of the receiving photocoupler 7, receiving circuit section 8, etc. are the same as those of the conventional example shown in FIG. 3, so
The explanation thereof will be omitted, and here, the explanation will focus on the points that are different from the above-mentioned conventional example.

First, the transmitting photocoupler 5 is connected between the communication control circuit section 4 and the transmitting circuit section 6.

Further, the drive power of the communication control device 3 is V1, G
It is roughly divided into 1, V2, and G2. Of these, V1,
G1 is used as a driving power source for the communication control circuit section 4, the receiving photocoupler 7, and the receiving circuit section 8. On the other hand, V2 and G2 are photocoupler 5 for transmission.
It is also used as a driving power source for the transmission circuit section 6.

And these drive power supplies V1, G1 and V2,
It is electrically separated from G2.

The communication control circuit device 3 of each computer system ₁₁ to _1o receives a transmission command and transmission data from the computer via the interface signal 9 with the computer of its own station, and transmits the transmission command and data at a predetermined timing and time by the communication control circuit section 4. format, and a transmission signal 10 is output.

The transmission signal 10 passes through the transmission photocoupler 5 (numeral 11 is the transmission signal after passing through the photocoupler 5), is converted into a predetermined output format by the transmission circuit section 6, and is output to the communication line 2 on the transmission side. .

On the other hand, the received signal 12 from the communication line 2 on the receiving side
is transmitted via the receiving photocoupler 7 (symbol 13
is the received signal after passing through the photocoupler 7), is converted into a predetermined input format by the receiving circuit section 8, and is sent to the communication control circuit section 4. In the communication control circuit section 4, the received signal 13 is converted into a predetermined timing and format, and a reception report and received data are sent to the computer of the own station via an interface signal 9. In addition, in this type of communication network, it is common to attach the sender and receiver addresses to the transmitted signal, and if the receiving computer system does not have the corresponding address, each computer system's address is The transmitted signal is transferred to the target computer system via the transmitting system, receiving system, and communication line 2.

In this embodiment, the transmitting photocoupler 5
and the reception photocoupler 7, and the drive power supplies V1, G1 for the communication control circuit section 4, the reception photocoupler 7, and the reception circuit section 8, and the drive power supplies V2, G2 for the transmission photocoupler 5 and the transmission circuit section 6. By electrically disconnecting, the power supply line of the communication control circuit section 4, the communication line 2 on the transmitting side, and the communication line 2 on the receiving side are electrically isolated from each other against noise carried on the communication line. be able to.

Therefore, even if noise is present on either the communication line 2 on the receiving side or the transmitting side, this noise will be transmitted to the communication control circuit section 4.
To prevent any trouble from occurring to the central part of the communication control system and eventually to the computer system without adversely affecting the power supplies V1 and G1 of the computer. In particular, the noise resistance can be greatly improved even in communication networks using long-distance wiring, which are considered to be highly influenced by noise.

Note that the noise transmitted to the transmitting side communication line 2 affects the power supplies V2 and G2, but since V2 and G2 are power supplies for transmission only, the communication control system is not disturbed by this, which is a function of the invention. As already mentioned. Even if noise is introduced into the receiving circuit section 8 as an error signal, there is no problem because the receiving circuit section 8 generally has an error processing function. In addition, this error processing is limited to the computer system of one section of the communication line where the noise occurs, and the influence of noise does not spread to the rest of the computer system, which has the advantage of reducing the burden of error processing and increasing system operating efficiency. (For example, when a transmitted signal contains noise, the receiving circuit section of the receiving computer system determines that the error signal due to the noise does not have a predetermined format and interrupts signal processing.) However, it is customary that the answer is not returned to the source via the loop communication line.If there is no answer, the source sends the transmission signal again).

〔Effect of the invention〕

As described above, according to the present invention, even in a computer system used in a loop-shaped communication network, the power supply system of the communication line 2 on the transmitting side, the communication line 2 on the receiving side, and the communication control circuit section 4 can be protected against noise. Since the three components are electrically insulated from each other, it prevents the influence of noise on the communication control system, which is the central part of the computer system, and greatly improves the noise resistance of the entire system, thereby increasing the reliability of this type of communication network as a whole. can be increased.

In addition, we aim to reduce the burden of noise error processing,
The operating efficiency of the computer system can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of a communication network to which the present invention is applied, FIG. 2 is a block diagram of a communication control device according to an embodiment of the present invention, and FIG. 3 is an example of a conventional communication control device. FIG. 1 ₁ ~ 1 _o ... computer system, 2 ... communication line, 3 ... communication control device for computer system, 4 ...
...Communication control circuit section, 5...Photocoupler for transmission,
6... Transmission circuit section, 7... Receiving photocoupler,
8... Receiving circuit unit, 9... Interface signal, 10, 11... Transmitting signal, 12, 13... Receiving signal, V1, G1... Communication control circuit unit driving power supply, V2, G2... Transmitting circuit unit Drive power supply.

Claims (1)

[Claims] 1. A plurality of computer systems 1 ₁ to 1 _o Communication lines 2 on the transmitting side and the receiving side, each connected to a different partner.
The communication control device 3 of each computer system ₁₁ to _1o used in this communication network communicates with the computer side of its own station via an interface signal 9. and a communication control circuit section 4 that controls transmission and reception on the communication line 2 side.
, a transmitting circuit section 6 that sends out the transmission signal from the communication control circuit section 4 to the communication line 2 on the transmitting side, and a receiving circuit section that inputs the received signal from the communication line 2 on the receiving side to the communication control circuit section 4. 8, and a transmitting photocoupler 5 is connected between the communication control circuit section 4 and the transmitting circuit section 6, a receiving photocoupler 7 is provided at the front stage of the receiving circuit section 8, and the communication control circuit section 4 and the receiving circuit section 8 are connected to each other. Photocoupler 7 and receiving circuit section 8
The driving power supplies V1, G1 and the driving power supplies V2, G2 of the transmitting photocoupler 5 and the transmitting circuit section 6 are provided separately, and these driving power supplies V1, G1, V2, G
A communication control device for a computer system used in a communication network, characterized in that two networks are electrically separated from each other.