JP2615169B2 - Optical transmission equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to an optical transmission device for performing data transmission between modules having a communication function such as a sequence controller and a personal computer.

[Prior art]

Conventionally, in data transmission between modules having a communication function such as a sequence controller and a personal computer, when a part of an optical transmission line which is a full-duplex type (hereinafter referred to as "full-duplex") double line is used and coupled, Other electrical transmission lines also had to be full duplex double tracks. The optical transmission device disposed between the electric transmission line and the optical transmission line converts communication data, which is an electric signal from the communication module, into an optical signal using a light emitting element, and converts the optical signal into an electric signal using a light receiving element. It has a function to convert to. Furthermore, if the light level (light amount) received by the light receiving element is checked and the level is below the stable operation level, a self-diagnosis function that alerts the outside with an alarm indicator, an alarm output circuit, or the like, the optical axis shift. Communication troubles due to contamination of the transmission window can be prevented in advance.

[Problems to be solved by the invention]

For the above-described optical transmission line which is a full-duplex double-track, the other electrical transmission lines are changed from full-duplex double-tracks to single-tracks of a half-duplex type (hereinafter referred to as "half-duplex") to simplify wiring. That is. Further, when it is desired to output an alarm signal of the optical transmission device to a display panel or the like of the equipment, it is necessary to provide a signal line dedicated to the alarm, which hinders simplification of wiring. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to change an electric transmission line coupled to an optical transmission line, which is a full-duplex double track, from a full-duplex double track to a half. An object of the present invention is to reduce the complexity of the wiring of the transmission line and improve the reliability by using a double single line.
It is another object of the present invention to enable alarms to be sent to a plurality of locations without arranging a special alarm signal line for outputting an alarm signal of an optical transmission device to a display panel or the like of a facility device.

[Means for Solving the Problems]

The configuration of the invention for solving the above problem is that communication data transmitted through a half-duplex transmission line passes through a receiver,
The optical data is converted into optical data by a modulator comprising an optical modulation circuit and transmitted to a full-duplex transmission line, or the optical data transmitted through the full-duplex transmission line is transmitted to a demodulator comprising an optical demodulation circuit. An optical transmission device which is converted to communication data by way of a driver and transmitted to the half-duplex transmission line via a driver, wherein a start bit in a data block of communication data passing through the receiver is detected, and at least the A first signal output circuit that outputs a signal of a predetermined level during a predetermined time during which the data block can be transmitted, and a start bit in a data block of communication data converted by the demodulator is detected; A second signal output circuit that outputs a signal of a predetermined level during a predetermined time during which transmission is possible, and outputs from the first signal output circuit and the second signal output circuit A switching signal for controlling the signal passing / blocking of the driver and the receiver to switch a transmission direction to the driver and the receiver in accordance with the signal and a data block transmission time of communication data from the time when the driver can transmit. A transmission direction switching signal output circuit that outputs a timing signal after a lapse of time, an optical level detection circuit that is connected to an input side of the demodulator and that outputs an optical level abnormality signal when the optical level is equal to or lower than a predetermined level; And a command generator for outputting alarm data to the driver in synchronization with a timing signal output from the transmission direction switching signal output circuit when a signal is being output.

[Action]

Communication data transmitted through a half-duplex transmission line passes through a receiver, is converted into optical data by a modulator, and is transmitted to a full-duplex transmission line. The optical data transmitted through the full-duplex transmission line is converted into communication data by the demodulator, and transmitted to the half-duplex transmission line via the driver. The first signal output circuit or the second signal output circuit constituting the optical transmission device
The signal output circuit detects a start bit in a data block of an output signal from the receiver or the demodulator, and outputs a signal for maintaining a transmission direction. And
The transmission direction switching signal output circuit that constitutes the optical transmission device performs half-duplex transmission by controlling the signal passage and cutoff of the driver and the receiver according to the output signals from the first signal output circuit and the second signal output circuit. In addition to switching the transmission direction of the line, the transmission direction switching signal output circuit outputs a timing signal after a data block transmission time of communication data elapses from the time when transmission by the driver is possible. When the optical level abnormality signal is output, the command generator outputs alarm data to the output side of the demodulator in synchronization with the timing signal output from the transmission direction switching signal output circuit.

【Example】

Hereinafter, the present invention will be described based on specific examples. First, description will be made with reference to FIG. 4 as an overall connection diagram. The communication module 30 and the optical transmission device 10 are RS422
(Balanced operation transmission circuit) Half-duplex combined with standard RS422 electrical transmission line (hereinafter referred to as "RS422 line"), and optical transmission equipment and optical transmission equipment are combined with optical transmission line and full-duplex It is. RS422 line ← → Optical transmission line ←
→ Communication data is exchanged between the communication modules via the transmission path of the RS422 line. FIG. 1 is a block diagram showing an electrical configuration of the present apparatus. The half-duplex RS422 line transmits and receives on one transmission path, and the full-duplex optical transmission line transmits and receives on two transmission paths dedicated to transmission and reception.
Route A on the RS422 line, route on the transmission side of the optical transmission line
B _S, when the reception side of the optical transmission line and path B _R, the transmission direction of the transmission signal, A → B _S, a two-way B _R → A. An optical transmission device 10 includes a receiver 11 as an RS422 communication circuit coupled to an RS422 line, and a modulator including an optical modulation circuit.
12, demodulator 13 composed of an optical demodulation circuit, driver 14 as a communication circuit for RS422 coupled to RS422 line, receiver 1
A first signal output circuit 15 for detecting a start bit in a data block of an output signal from 1 and outputting a signal of a predetermined level for at least a predetermined time during which the data block can be transmitted, and data of an output signal from a demodulator 13 The output from the second signal output circuit 16, the first signal output circuit 15, and the output from the second signal output circuit 16 for detecting a start bit in the block and outputting a signal of a predetermined level for at least a predetermined time during which the data block can be transmitted. While outputting a transmission direction switching signal to the receiver 11 and the driver 14 according to the signal,
A transmission direction switching signal output circuit 17 that outputs a timing signal after a data block transmission time of communication data elapses from a time when transmission of the driver 14 is possible, an inversion signal output circuit 18 that inverts an output signal of the transmission direction switching signal output circuit 17, The light level detection circuit 19, which constantly detects the light level from within the stable operation level, is synchronized with the timing signal output from the transmission direction switching signal output circuit 17 when the light level abnormality signal is output from the light level detection circuit 19. And a command generator 20 for generating a level abnormal command. Here, the communication data is a serial digital signal (baseband) as shown in FIG. 2, and the data block starts with the start bit of the first data and ends with the stop bit of the last data. The time t from the start bit to the stop bit is the transmission time of the data block of the communication data, and the time length of the output signal from the first signal output circuit 15 and the second signal output circuit 16 is the time t. The timer is set as a timer longer than the sum of the transmission time of the level abnormal command generated from the command generator 20, that is, the timer capable of transmitting the level abnormal command after the data block of the communication data. Next, the operation will be described. First, when the communication module device is turned to the power ON state, the optical transmission device 10 is path A side, waits in a state capable of communicating data be transmitted from either side of the path B _R side. That is, the output signal of the transmission direction switching signal output circuit 17 in the standby state is always at the L level, and the driver 14 is inactivated,
Further, the output signal of the inversion signal output circuit 18 becomes H level, and the receiver 11 is activated. Therefore, the monitor path A side of the communication data whether the first signal output circuit 15 of the presence or absence of communication data path B _R side at the second signal output circuit 16. Next, when communication data is input to the route A,
Since the receiver 11 is in operation, the first signal output circuit 15
Normally outputs a signal of L level, detects a point where the start bit of the data block of communication data changes from H level to L level, and outputs a signal of H level for a predetermined time during which the data block of communication data can be transmitted. Output level signal.
At this time, if the communication data path B _R side is not inputted, the second signal output circuit 16 outputs the L level signal. Then, as in the standby state, the transmission direction switching signal output circuit 17 keeps outputting the L level signal, and maintains the operating state of the receiver 11 and the inactive state of the driver 14. Here, communication data is input from the path _BR side during the setting timer of the first signal output circuit 15 for the data block of the communication data input to the path A side, and the output signal of the second signal output circuit 16 is output. Even if it changes from L level to H level,
The output signal of the transmission direction switching signal output circuit 17 remains at the L level, and the operating state of the receiver 11 and the inactive state of the driver 14 do not change. Therefore, at this time, even if the light level of the communication data input from the path B _R side has become a predetermined level or less, together with the communication data path A side, will not be a warning data level abnormality command is transmitted . By controlling in this manner, reception is prioritized over transmission, and collision of communication data on the half-duplex path A side is prevented. Next, when no communication data is input to the route A,
When the communication data to the route B _R side is input, the first signal output circuit 15 has outputs an L level signal, the second signal output circuit 16 typically outputs a L level signal Yes,
H which is the start bit of the data block of the communication data
A point at which the level has changed from L level to L level is detected, and an H level signal is output from that time until the end of a predetermined time during which a level abnormal command can be transmitted after the data block of the communication data. Then, the output signal of the transmission direction switching signal output circuit 17 becomes L in synchronization with the output signal of the second signal output circuit 16.
It changes from level to H level. Accordingly, the driver 14 switches the operating state, at the same time, the output signal of the inverted signal output circuit 18 since the L level receiver 11 becomes inoperative, the communication data is transmitted from the route B _R side to the path A side. The setting of the second signal output circuit 16 corresponding to the period from the start bit of the data blocks of the communication data is input to the path B _R side to a level abnormality command after the data block has passed a predetermined time transmittable When the timer expires, the output signal changes from H level to L level, and returns to a receivable state accordingly. FIG. 3 is a time chart showing the relationship between communication data on the RS422 line, a level abnormality command when an optical level abnormality occurs, a timer, and the like. When light level of the optical data input from the path B _R side is at a predetermined level or less,
The light level detection circuit 19 outputs an H level light level abnormality signal. The transmission direction switching signal output circuit 17 activates a timer capable of transmitting a data block of communication data from the time when the output signal is changed from L level to H level. When the timer times out, the level changes from L level to H level, and after the output period of the level abnormal command has elapsed, the level becomes low.
A timing signal for returning to the level is output to the command generator 20. When the light level detection circuit 19 is in the output state of the H level light level abnormality signal, the command generator 20 outputs a level abnormality command, which is alarm data, to the driver 14 in synchronization with the rise of the timing signal. And
After the level abnormal command is transmitted, the output signal of the transmission direction switching signal output circuit 17 changes from H level to L level,
The driver 14 is again disabled. At the same time, the output signal of the inverted signal output circuit 18 becomes H level, so that the receiver 11 returns to the operating state. In this way, it is possible to notify the other communication modules that the light level has decreased by the level abnormality command. In the above description, the set timer time of the second signal output circuit 16 is defined as the time when the start bit of the communication data block is detected, that is, when the point at which the change from H level to L level is detected starts. The time until the predetermined time during which the level abnormal command after the time can be transmitted elapses, but the set timer time of the second signal output circuit 16 is the time until the predetermined time during which the data block of the communication data can be transmitted. A timing signal that changes to the H level in synchronization with the return of the output signal of the second signal output circuit 16 from the H level to the L level and continues the H level for the transmission time of the abnormal level command may be output. or,
In this case, the output signal of the transmission direction switching signal output circuit 17 is maintained at the H level until the timing signal returns from the H level to the L level. In the optical transmission device having such a configuration, the route A
Since the RS422 line is half-duplex and can be transmitted and received through one transmission path, the transmission line is simplified and the reliability of the transmission line is improved. Since the alarm data when the light level falls below the predetermined level is transmitted through the existing transmission line, even if the signal line dedicated to the alarm is not wired, it is received by multiple communication modules and the alarm is displayed on the display panel etc. And preventive measures can be taken before a communication trouble occurs between the communication modules, thereby improving reliability. The circuit configuration of such an optical transmission device can be realized using ICs such as a gate circuit, a flip-flop circuit, and a timer circuit, and each circuit element can be efficiently mounted on a printed circuit board. Since the device can be provided at a small size and at a low price, the cost required for laying the entire transmission line including the optical transmission device can be reduced.

【The invention's effect】

The present invention detects a start bit in a data block of communication data converted via a receiver or a demodulator, and outputs a signal of a predetermined level at least for a predetermined time during which the data block can be transmitted. Circuit or a second signal output circuit, and a switching signal for switching a transmission direction by controlling signal passing / blocking of a driver and a receiver according to output signals from the first signal output circuit and the second signal output circuit. And a transmission direction switching signal output circuit for outputting a timing signal after a data block transmission time of communication data has elapsed from a time when the driver can transmit, and when an optical level connected to an input side of the demodulator is equal to or lower than a predetermined level, An optical level detection circuit that outputs an optical level abnormal signal, and a transmission direction when an optical level abnormal signal is output. In synchronism with the timing signal output from the signal output circuit, since it has a command generator for outputting a warning data to the driver, which simplifies the transmission lines, thereby improving reliability. Further, when the light level falls below a predetermined level, alarm data is transmitted to the simplified transmission line, received by a plurality of communication modules, and an alarm can be output to a display panel or the like. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of an optical transmission device according to a specific embodiment of the present invention. FIG. 2 is an explanatory diagram showing communication data according to the embodiment. FIG. 3 is a time chart showing the relationship between communication data on the RS422 line, a level abnormality command when an optical level abnormality occurs, a timer, and the like according to the embodiment. FIG. 4 is an explanatory diagram showing the entire transmission path including the optical transmission device according to the embodiment. 10 …… optical transmission equipment, 12 …… modulator, 13 …… demodulator, 19…
... Light level detection circuit, 20 ... Command generator, 30 ... Communication module

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naonaka Nakamura 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Yoichi Shibata 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation ( 72) Inventor Takeshi Yamashita 1-1, Asahi-cho, Kariya-shi, Aichi Prefecture Toyota Koki Co., Ltd. (72) Inventor Toshihiro Mori 2-1-1, Sonezaki, Kita-ku, Osaka-shi, Osaka Hokuyo Electric Co., Ltd.

Claims (1)

(57) [Claims] 1. Communication data transmitted through a half-duplex transmission line is converted to optical data by a modulator comprising an optical modulation circuit via a receiver, and transmitted to a full-duplex transmission line. Alternatively, optical data transmitted through a full-duplex transmission line is converted into communication data by a demodulator including an optical demodulation circuit, and transmitted via a driver to the half-duplex transmission line. An apparatus, comprising: a first signal output circuit that detects a start bit in a data block of communication data transmitted through the receiver and outputs a signal of a predetermined level at least for a predetermined time during which the data block can be transmitted; A start bit in a data block of communication data converted by the demodulator is detected, and a signal of a predetermined level is output at least for a predetermined time during which the data block can be transmitted. A second signal output circuit, and a switching signal for switching a transmission direction by controlling signal passing / blocking of the driver and the receiver according to output signals from the first signal output circuit and the second signal output circuit. A transmission direction switching signal output circuit that outputs to the driver and the receiver and outputs a timing signal after a data block transmission time of communication data elapses from the time when the driver can transmit, and an optical level connected to an input side of the demodulator. An optical level detection circuit that outputs an optical level abnormality signal when the optical level abnormality signal is below a predetermined level; and, when the optical level abnormality signal is output, an alarm data in synchronization with a timing signal output from the transmission direction switching signal output circuit. And a command generator that outputs the command to the driver.