KR101113152B1 - Method of sensing abnormal state and controlling of rs485 communication system - Google Patents

Abstract

The present invention relates to an abnormal state detection and control method of the RS485 optical communication system. According to the present invention, in the abnormal state detection and control method of an RS485 optical communication system in which a plurality of optical converters are connected in a ring mode, detecting a frequency of an optical signal input from another optical converter, the optical having a first frequency Determining whether the signal continues to be input for the first period, and when the optical signal having the first frequency is input for the first period, after the first period has elapsed, for a second frequency Delivering an optical signal having a.
As described above, according to the present invention, the optical converter operating in the ring mode can be easily detected as an abnormal state due to an internal problem, and automatically resets the RS485 optical communication system after detecting the abnormal state, thereby functioning normally. Make it work smoothly.

Description

Ｓ４４５ Abnormal Condition Detection and Control Method of Optical Communication System {METHOD OF SENSING ABNORMAL STATE AND CONTROLLING OF RS485 COMMUNICATION SYSTEM}

The present invention relates to an abnormal state detection and control method of an RS485 optical communication system, and more particularly, to an abnormality of an RS485 optical communication system capable of easily detecting an abnormal state of an RS485 optical communication system in which a plurality of optical converters are connected in a ring mode. It relates to a state detection and control method.

In general, RS485 is a TIA / EIA (Telecommunications Industry Association / Electronics Industry Association) standard for multi-point communication lines and supports connectors such as DB-9 and DB-37. RS-485 can connect up to 32 drivers and receivers from one of the serial transmission interface specifications.

RS485 is similar to RS422, but by using a low impedance driver and receiver, it allows more nodes per line than RS422. In other words, RS485 is the same series as RS422, and RS423 is a graded down RS422 to endless, unbalanced transmission. Would have done so. In addition, RS485 is highly compatible with RS422, and what is suitable for RS485 is also suitable for RS422. Although the transmission distance of RS485 is up to 1200m, it is changed by the transmission speed (10 Mbps: 12m, 1 Mbps: 120m, 100 Kbps: 1200m), which is more noise-resistant than RS232C, and enables high-speed transmission.

By using the characteristics of the RS485 as described above it is possible to implement an optical converter in the ring mode. However, in the case of the optical converter implemented in the ring mode, data is circulated and transmitted between the optical converters. Therefore, when an abnormal state is caused due to a connection problem between the optical converters or a connection problem between the optical converter and the communication terminal, the abnormal state is facilitated. There is a problem that can not be found.

Accordingly, an object of the present invention is to provide an abnormal state detection and control method of an RS485 optical communication system that can easily detect an abnormal state of an RS485 optical communication system in which a plurality of optical converters are connected in a ring mode.

According to an embodiment of the present invention for achieving the technical problem, in the abnormal state detection and control method of the RS485 optical communication system in which a plurality of optical converters are connected in a ring mode, the frequency of the optical signal input from another optical converter Sensing, determining whether an optical signal having a first frequency is inputted continuously for a first period, and if the optical signal having the first frequency is inputted continuously for the first period, the first period Passing an optical signal having a second frequency for a second period after the elapsed time.

The optical converter may convert an electrical signal of an RS485 optical communication protocol received from a communication terminal into an optical signal, or convert an optical signal into an electrical signal.

The first frequency may correspond to a low level electrical signal, and the second frequency may correspond to a high level electrical signal.

The first period may be 33 ms to 34 ms, and the second period may be 1 ms to 3 ms.

When the optical signal having the first frequency lasts for the first period, transferring the optical signal having the second frequency during the second period may convert the RS communication state into a mark state in a standby state. .

According to another embodiment of the present invention, in an RS485 optical communication system in which a plurality of optical converters are connected in a ring mode, the optical converter is characterized in that an optical signal having a first frequency input from another optical converter lasts for a first period of time. If the optical signal having the first frequency lasts for the first period, the optical signal having the second frequency is transmitted during the second period after the first period elapses.

As described above, according to the present invention, the optical converter operating in the ring mode can be easily detected as an abnormal state due to an internal problem, and automatically resets the RS485 optical communication system after detecting the abnormal state, thereby functioning normally. Make it work smoothly.

1 is a view for explaining an RS485 optical communication system according to an embodiment of the present invention.
Figure 2 shows an optical signal transmitted between the optical signal and the electrical signal of the RS485 protocol system that the communication terminal transmits to the optical converter.
3A and 3B are RS485 communication waveform diagrams for explaining the normal state and the abnormal state.
4 is a flowchart illustrating an abnormal state detection and control method of an RS485 optical communication system according to an exemplary embodiment of the present invention.
5 is a RS485 communication waveform diagram according to an embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

1 is a view for explaining an RS485 optical communication system according to an embodiment of the present invention. Referring to FIG. 1, in the RS485 optical communication system according to an exemplary embodiment of the present invention, a plurality of optical converters 100 are connected in a closed form, and the plurality of optical converters 100 are connected by an optical cable. According to the RS485 optical communication system, 32 optical converters 100 are connected in a closed form to perform serial communication. In FIG. 1, four optical converters are shown for convenience of description. Each optical converter 100 includes a transmission port Tx and a reception port Rx, and the transmission port Tx and the reception port Rx are connected through an optical cable. Therefore, the optical converters 100 transmit data through the transmission port Tx and receive data through the reception port Rx.

Each optical converter 100 may be connected to a communication terminal such as a PC, a PLC, an IP camera, and the like, and the plurality of terminals may be connected in a multi drop form. In addition, the optical converter 100 and the communication terminals are connected to a wire made of a conductive material such as copper.

Therefore, the communication terminal transmits an electrical signal following the RS485 protocol to the connected optical converter 100, and the optical converter 100 converts the electrical signal into an optical signal and transmits the optical signal to another optical converter.

That is, the optical converter 100 converts an optical signal into an electrical signal, or converts the electrical signal into an optical signal.

The optical converter 100 converts data in the form of an electrical signal received from the communication terminal into an optical signal and transfers the data in the form of an optical signal received from another optical converter 100 to the other optical converter 100. Convert it and deliver it to the communication terminal.

Figure 2 shows an optical signal transmitted between the optical signal and the electrical signal of the RS485 protocol system that the communication terminal transmits to the optical converter.

As shown in FIG. 2, the communication terminal transmits data to the optical converter 100 by using a high level signal '1' and a low level signal '0'. The optical converter 100 converts an optical signal of 4.167 MHz and transmits data to another optical converter 100 when '1' is input through the RS485 protocol. In addition, when optical signal data of 4.167 MHz is input from another optical converter 100, the signal is converted into an electrical signal '1' and transmitted to the communication terminal.

The optical converter 100 transmits data to another optical converter 100 by converting an optical signal of 8.333 MHz when '0' is input through the RS485 protocol. In addition, when the optical signal data of 8.333MHz is input from the other optical converter 100, it is converted into an electrical signal '0' and transmitted to the communication terminal.

3A and 3B are RS485 communication waveform diagrams for explaining the normal state and the abnormal state. 3A is a communication waveform in which the communication terminal on the transmission side transmits data to the optical converter 100 in a normal state, and FIG. 3B is a communication waveform in which the communication terminal on the transmission side transmits data to the optical converter 100 in an abnormal state.

According to the communication waveform between the communication terminal and the optical converter 100 in the normal state, as shown in FIG. 3A, the communication terminal goes high to the optical converter 100 in the mark state in the idle state without data transmission. Transmit the level signal '1'. In this case, as described above, the optical converter 100 receiving the electrical signal '1' converts into an optical signal of 4.167 MHz and transmits data to another optical converter 100.

When data starts to be input, the communication terminal transmits a low level signal '0' as a start bit. That is, when data is input, the communication terminal transmits a low level signal '0' to the optical converter 100 for a period of 1 bit. Similarly, the optical converter 100 receiving the electrical signal '0' converts into an optical signal of 8.333 MHz and transmits data to another optical converter 100.

Here, the communication speed of the communication terminal is determined according to the version or characteristics of the product to which the communication terminal is applied, and in the embodiment of the present invention, it will be described as having 300bps. Therefore, the start bit is input for 1/300 second corresponding to 1 bit.

After the start bit is input as described above, data bits corresponding to 8 bits are input. The data bits include various control signals and transmission data which the communication terminal intends to transmit to the optical converter. After the data bits corresponding to 8 bits, parity bits and stop bits corresponding to 1 bit are transmitted. The parity bit is a bit for facilitating error detection, and the stop bit is a signal indicating that data transmission is completed and always has a value of '1', which is a high level signal. As described above, according to the RS485 protocol, data is transmitted in a total of 10 bit units of a start bit (1 bit), a data bit (8 bit), and a parity bit (1 bit).

Therefore, in the normal state, data is transmitted in 10-bit units, and the time required for data transmission is about 33 ~ 34ms in case of 300bps.

According to the communication waveform between the communication terminal and the optical converter 100 in the abnormal state, as shown in FIG. 3B, a '0' signal, which is a low level signal, is maintained for a predetermined period after the mark state. A communication waveform as shown in FIG. 3B is generated when a connection is poor or a problem occurs in a power supply between the plurality of optical converters 100 constituting the ring mode. It may not receive data or transmit data to another optical converter 100.

That is, in the normal state, if there is no data transmission, it returns to the mark state again after a certain period of time, but in the abnormal state as shown in FIG. Even if the data is transmitted to the optical converter 100, the optical converter 100 may not read the data and may not transmit the data to the other optical converter 100.

That is, as described above, in the normal state as shown in FIG. 3A, the bit ('1'), the start bit ('1'-> '0'), and the data bit ('1' or '0') of the mark state, eight bits. ), The parity bit ('1' or '0') and the end bit ('1') are sequentially input and then returned to the mark state, but in the abnormal state as shown in FIG. 3B, the mark state (' 1 '), the optical converter 100 can no longer receive or transmit data.

4 is a flowchart illustrating an abnormal state detection and control method of an RS485 optical communication system according to an exemplary embodiment of the present invention. 5 is a RS485 communication waveform diagram according to an embodiment of the present invention.

First, as shown in FIG. 1, the plurality of optical converters 100 are connected in a closed manner to perform an operation in a ring mode (S410). In particular, in the RS485 optical communication system, 32 optical converters are connected in a ring shape, and the optical converter 100 transmits a signal input through the reception port Rx to another optical converter through the transmission port Tx.

That is, as described with reference to FIG. 3A, in the normal state, the bit ('1') of the mark state, the start bit ('1'-> '0'), the data bit ('1' or '0'), and the parity bit (' 1 'or' 0 '), the end bit (' 1 ') is sequentially input from the communication terminal to the optical converter 100, the optical converter 100 converts the electrical signal' 1 'into an optical signal of 4.167MHz Convert the electrical signal '0' into an optical signal of 8.333MHz. The optical converter 100 transmits the converted 4.167 MHz or 8.333 MHz optical signal to another optical converter.

The optical converter 100 senses the frequency of the optical signal input through the receiving port Rx (S420). Here, the optical converter 100 senses an electric signal input from a communication terminal as well as a frequency of an optical signal input from another optical converter.

The optical converter 100 determines whether an optical signal having a frequency of 8.333 MHz input through the reception port Rx lasts 34 ms or more (S430).

That is, as described with reference to FIG. 3a, in the normal state, it takes about 33 to 34 ms for the data to be transmitted in 10-bit units at 300 bps, and new 10-bit data is input after 34 ms. Therefore, the master optical converter directly connected to the communication terminal determines whether the electrical signal '0' is inputted for more than 34ms and has a frequency of 8.333 MHz in the case of the slave optical converter which receives the optical signal from other optical converters. Determine whether the optical signal is input for more than 34ms.

If an optical signal having a frequency of 8.333 MHz is inputted for more than 34 ms, the optical converter 100 determines an abnormal state such as power instability, optical cable connection error, or abnormal data generation as shown in FIG. During transmission, the optical signal having the frequency of 4.167 MHz is transmitted to another optical converter and reset (S440). That is, in an abnormal state, since an optical signal having a frequency of 8.333 MHz is continuously transmitted to other optical converters connected in a ring form, an optical signal having a frequency of 4.167 MHz is transmitted for 1 to 3 위해서 to forcibly release it. Preferably 2 ms is suitable.

As shown in FIGS. 3A and 3B, the mark state must be started from the electrical signal '1', so that if the electrical signal '0' is maintained, the mark state is not returned. Therefore, after 34ms has elapsed, an optical signal having a frequency of 4.167 MHz corresponding to the electrical signal '1' is transmitted to be reset to a mark state.

Here, since up to 32 optical converters 100 are connected in a ring shape, some time is required for resetting, and thus, an optical signal having a frequency of 4.167 MHz is transmitted for 1 to 3 kHz. When the plurality of optical converters 100 implemented in the ring mode are returned to their normal state, the process returns to step S420 and the optical converter 100 monitors the frequency input through the receiving port Rx.

As described above, according to the present invention, the optical converter operating in the ring mode can be easily detected as an abnormal state due to an internal problem, and automatically resets the RS485 optical communication system after the detection of the abnormal state, thereby resuming the function of the optical converter. Make it work smoothly.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

100: optical converter

Claims (10)

In the abnormal state detection and control method of the RS485 optical communication system in which a plurality of optical converters are connected in a ring mode through an optical cable,
The optical converter detects a frequency of an optical signal input from a neighboring first optical converter,
Determining whether an optical signal having a first frequency corresponding to the low level signal continues to be input for a first period of time, and
When the optical signal having the first frequency is continuously input for the first period, a second signal is converted into an optical signal having a second frequency corresponding to a high level signal and neighbors for a second period shorter than the first period. Abnormal state detection and control method of the RS485 optical communication system comprising the step of transmitting to the optical converter. The method of claim 1,
The optical converter,
An abnormal state detection and control method of an RS485 optical communication system converting an electrical signal of an RS485 optical communication protocol received from a communication terminal into an optical signal or converting an optical signal into an electrical signal. delete The method of claim 1,
Wherein the first period is 33ms to 34ms, and the second period is 1ms to 3ms. The method of claim 1,
When the optical signal having the first frequency lasts for the first period, converting the optical signal having the second frequency to the second optical converter during the second period may include:
An abnormal state detection and control method of an RS485 optical communication system for converting the RS communication state into a mark state in a standby state. In an RS485 optical communication system in which a plurality of optical converters are connected in a ring mode through an optical cable,
The optical converter,
It is determined whether the optical signal having the first frequency input from the neighboring first optical converter lasts for the first period, and when the optical signal having the first frequency lasts for the first period, it corresponds to the high level signal. RS485 optical communication system for converting into an optical signal having a second frequency to be transmitted to the neighboring second optical converter for a second period shorter than the first period. The method of claim 6,
The optical converter is an RS485 optical communication system for converting an electrical signal of the RS485 optical communication protocol received from the communication terminal into an optical signal, or converts the optical signal into an electrical signal. delete The method of claim 6,
And the first period is 33ms to 34ms, and the second period is 1ms to 3ms. The method of claim 6,
An RS485 optical communication system for transferring the optical signal having the second frequency during the second period to convert the RS communication state into a mark state in standby state.

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