JP2000292309A - Optical fieldbus equipment - Google Patents

Abstract

(57) [Problem] To provide an optical fieldbus device which outputs an optical signal for maintenance for a fixed time and facilitates inspection of an optical transmission system. Kind Code: A1 A central device 1 and a local device 3, a local device 3 and a central device 1 and a central device 3 and a local device 3
A switch for setting a maintenance mode in an optical fieldbus device 3 connected via an interface circuit 31 to an optical fieldbus 5 for performing data transmission between them
46, determining means for shifting the optical fieldbus device 3 to the maintenance mode in response to a command by operating the switch 46 or a command by inputting a command from the optical fieldbus 5, and in advance for inspecting the optical signal transmission system in the maintenance mode. Output means for outputting an optical signal for maintenance for a predetermined period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fieldbus device used in process automation and factory automation, and more particularly to an optical fieldbus device which is connected to an optical fieldbus and which is easy to maintain and suitable.

[0002]

2. Description of the Related Art Conventionally, as a field device for measurement control using an optical signal using an optical fiber as a transmission medium, there is an "FFI system" (optical fiber field measurement control system) of those skilled in the art. FIG. 4 shows a system configuration diagram of the FFI system. In FIG. 4, reference numeral 1 denotes a higher-level device, for example, a data processing device installed in a distant control room or a measurement control device for performing control and the like. Reference numeral 9 denotes optical field devices B1, B2, B3,... Bn installed on the site. The optical field devices 9 measure the measurement amounts such as flow rate, pressure, temperature, and level, and transmit the measurement data to the host device 1. It is transmitted by an optical signal, or receives control data from the host device 1 to control a control valve and the like.
Measures measured quantities such as temperature and level,
It has a function of a local control device that outputs a control output for performing PID arithmetic control, controls a control valve and the like, receives various control parameters from the host device 1, and transmits various management data to the host device 1.

Reference numeral 8 denotes an optical splitter. In an embodiment of the prior art FFI system, 2: n (n = 8) optical splitters are performed.
Optical fibers 51, (52) are provided between the optical branching device 8 and the host device 1.
The optical branching device 8 and the optical field devices B1, B2, B3,... Bn are connected by an optical fiber 6 (61, 62, 63,... 6n). Equipment 9 (B1, B2, B3
-1: n star connection with Bn) as the slave unit is performed.
In a system that requires high reliability, the transmission path to the host device 1 is made double redundant and a 2: n star connection is performed.

FIG. 5 is a block diagram showing a conventional optical field device 9. As shown in FIG. In FIG. 5, the optical field device 9 includes a receiving unit 33 and a transmitting unit 34 connected to the optical fiber 6.
, An interface unit 91 including a modem unit 35, a central processing unit 41, and a memory unit 43.
Peripheral device 42, which includes an I / O unit 44, and a modem unit 35
And an internal bus 45 connecting the central processing unit 41 and the peripheral device 42.

In such a configuration, for example, detection signals from sensors (not shown) such as flow rate, pressure, temperature, and level are taken into the I / O section 44 of the peripheral device 42 and measured by the central processing unit 41, for example. The data is stored in the memory unit 43 after performing a range, a linearization process of the measurement signal, or a temperature / pressure correction process of the flow rate.

The transmission frame addressed to the own station received by the receiving section 33 via the optical fiber 6 is decoded by the modem section 35 and converted into received data. The received data includes, for example, various parameters such as a zero point, a span, and a correction range from the host device 1 to the sensor function of the optical field device 9 and the optical field device 9 having a local control device function.
There are control parameters such as PID, and these data are stored in the memory unit 43 of the peripheral device 42 and read out and used by the central processing unit 41 as appropriate.
The control output data for the control valve and the like is output from the I / O unit 44 of the peripheral device 42 to control the control target. The sensor data and the like obtained by the optical field device 9 are converted into a transmission frame by the modem unit 35, and
At 34, it is converted to an optical signal and output to the optical fiber 6.

In the field device 9 for measuring and controlling by such optical signals according to the prior art, a maintenance mode is switched on the field device side, and an optical signal for maintenance is output for a certain time in order to inspect the transmission system of the optical signal. Optical device, optical connector, optical splitter 8, and optical fiber 5
It does not have a function to perform a consistent inspection of the optical signal transmission system including 1, 52, and 6, and the inspection of these optical signal transmission systems measures each individual component and integrates these measured values. It was mainly to determine the optical loss by using

[0008]

According to the conventional optical signal transmission system inspection method, when an abnormality of a certain optical transmission system is found and it is desired to inspect the system, an optical signal for maintenance is transmitted to the optical field device. Since there is no function to output for a certain period, for example, when it is desired to determine whether the light emitting element of the transmitting unit of the optical field device outputs an optical signal power equal to or higher than a predetermined reference value, the unit of the optical transmitting and receiving unit It had to be inspected after removing the optical signal. In addition, when inspecting whether the optical fiber and the optical branching device have deteriorated or the light loss has increased due to dirt, it is necessary to connect another inspection light source and inspect the light source. Numerical A
perture) NA (sine value of the maximum angle that the optical fiber can receive)
Due to the difference between the two, or due to an optical loss error due to the attachment or detachment of an optical fiber, there is a problem in that it is inconvenient to prepare another light source and inaccurate in determining an appropriate situation.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to solve the above-mentioned problems, to output an optical signal for maintenance for a fixed time, and to facilitate inspection of an optical transmission system. It is to provide a fieldbus device.

[0010]

In order to solve the above problems, an optical fieldbus device according to the present invention is an optical fieldbus device for connecting a master unit and a slave unit via an optical communication path. Means for causing the central processing unit to transition to the maintenance mode, means for transmitting an optical signal for measurement during a certain period from the slave unit to the master unit in response to this transition, and receiving the optical signal for measurement Means for determining whether or not the optical signal is at or above a predetermined level.

By transmitting a command from the master unit via the optical transmission system, the central processing unit of the slave unit can be shifted to the maintenance mode. Further, the central processing unit of the slave unit can be shifted to the maintenance mode by the operation switch provided on the slave unit side.

With such a configuration, the central processing unit can receive a command by operating the maintenance mode setting switch or a command by inputting a command from the optical field bus.
A transition is made to the maintenance mode, and an output signal of the maintenance mode is output for a predetermined period of time. The output means performs an OR operation on the transmission output signal from the modem unit and the maintenance mode output signal of the central processing unit. The output can drive the transmission section of the optical transmission / reception section to output an optical signal to the optical field bus.

[0013]

FIG. 1 is a system configuration diagram using an optical fieldbus device as an embodiment of the present invention, FIG. 2 is a block diagram of an optical fieldbus device as an embodiment of the present invention, and FIG. Is a frame configuration diagram of a transmission signal, and the same members corresponding to FIGS. 4 and 5 are denoted by the same reference numerals.

In FIG. 1, a system configuration using the optical fieldbus device of the present invention includes an upper device 1 installed in a central control room or the like and an optical fieldbus device installed in a field as a field device (slave device). 3 (A1, A2, A3 ・ ・ ・
An) and an optical field bus 5 for performing data transmission between these devices 1 and 3. The optical field bus 5 is configured to perform data transmission by an optical signal between the center 1 and the field device 3, between the field devices 3, or between the center 1 and the field device 3 and between the field devices 3. ing. In the present invention, the optical field bus 5 and the optical field bus device 3 are connected by a 1: n (or 2: n) star connection between the center (master) and the field device (slave) described in the related art. Is used in the broad sense of transmission by means of n: n bus connection including the above and devices connected to this transmission path.

The optical fieldbus device 3 is provided with a switch 46 for setting a maintenance mode, and a discriminating means for transiting the optical fieldbus device 3 to the maintenance mode in response to a command by operating the switch 46 or a command by inputting a command from the optical fieldbus 5. And an output unit for outputting an optical signal for maintenance for a predetermined period for inspecting the optical signal transmission system in the maintenance mode.

With such a configuration, the optical fieldbus device 3 can operate the optical fieldbus device 3 as a slave device in response to a command from the operation of the maintenance mode setting switch 46 or a command from the host device 1 as a master device. The central processing unit (CPU) 41 is shifted to the maintenance mode, a maintenance signal is output for a predetermined period of time in this maintenance mode, an OR operation with the output of the modem unit 35 is performed, and an optical signal is transmitted from the transmission unit 34. It can be output for a certain period.

[0017]

1, an upper device 1 is connected to an optical splitter 2 via an optical fiber 51, and each of the optical field bus devices 3 (A1, A2, A3. An) are connected to optical fibers 61, 62, 63,... 6n, and a communication path (optical field bus 5) is formed via optical signals. The optical signal output from the host device 1 is equally distributed to the optical fibers 61, 62, 63,... 6n by the action of the optical splitter 2 (n: n), and the respective optical field bus devices A1, A2, A3,.・ Output to An. Also,
Similarly, when an arbitrary optical fieldbus device 3 (for example, A1; hereinafter, A1 is a representative example) outputs an optical signal, the optical signal output to the optical splitter 2 via the optical fiber 61 is an optical branch. By the operation of the devices 2 (n: n), the signals are equally distributed and output to the host control device 1 and the optical fieldbus devices A2, A3,.

Here, a case where an abnormality occurs in the transmission system of the optical fieldbus device 3 connected to the higher-level control device 1 via the optical fiber 51, the optical splitter 2, and the optical fiber 6 will be described. In the prior art, as described above, first, a light source is arranged at the position of the host device 1 for inspection of the transmission path (the optical fiber 51, the optical splitter 2, and the optical fiber 61), and light is emitted.
An optical power meter is disposed at the position of the optical field device 9 (in the prior art, not an optical fieldbus device but an optical device of another communication protocol), and the optical loss value is measured.

On the other hand, when the optical fieldbus device 3 (A1) according to the present invention is used, a handheld communicator having the function of the optical power meter 7 is a maintenance tool exchanged and connected from the upper device 1 or at the position of the upper device 1. By transmitting a command for transition to the maintenance mode to the optical fieldbus device 3 (A1) from the optical fieldbus device 3, the optical signal for optical signal power measurement can be transmitted from the optical fieldbus device 3 (A1) for a certain period of time. As a result, the host device 1 transmits the maintenance mode transition command to the optical fieldbus device A1 and then connects the optical fiber 51 to the optical power meter 7.
The optical power meter 7 can be used to check whether the incoming optical signal from the optical fieldbus device A1 has a predetermined power level or more.

Here, the reason why the optical fieldbus device 3 transmits an optical signal for optical signal power measurement only for a certain period of time is that, on the other hand, the connection exchange time of the optical fiber 5 and the power level measurement by the optical power meter 7 are performed. It is necessary to emit light continuously for an estimated time and on the other hand, while the optical fieldbus device A1 is transmitting the optical signal for measuring the optical signal power, the optical fieldbus 5 is occupied by the transmission signal. ,
Since communication with other stations including the own station is hindered, practically,
The duration of light emission of the optical signal for measuring the optical signal power is suitably about 1 to 5 minutes.

If there is a serious failure in the optical signal path and it is not possible to switch to the maintenance mode by a command operation via communication, the maintenance switch 46 provided on the optical fieldbus device 3 is used for maintenance. The optical fiber 51 is connected to the optical power meter 7 and exchanged, and the incoming signal from the optical field bus device A1 is received by the optical power meter 7. The power level of the optical signal can be checked.

In any case, the incoming optical power level up to the host device 1 can be inspected without disconnecting the optical fiber 6 connected to the optical fieldbus device 3, so that, for example, the installation environment as a field device Even if the optical fieldbus equipment 3 is installed in a poor field environment,
Since there is no need to attach and detach the optical fiber 6 for maintenance, accurate measurement can be performed without being affected by adhesion of dust or the like due to attachment or detachment of the optical fiber 6, attachment / detachment errors, and measurement value errors due to differences in light sources.

Next, in FIG. 2, the optical fieldbus device 3 is connected to the optical fieldbus device 3 via the optical fieldbus 5 from the upper control device 1 or from the handheld communicator exchange-connected to the position of the upper control device 1. Consider a case in which a command for transitioning No. 3 to the maintenance mode is received, and the optical transmitting / receiving unit 32 normally receives an optical signal. The received command signal for the maintenance mode transition is subjected to reception processing by a modem unit 35 connected to the optical transmission / reception unit 32, as described later, and then processed by the central processing unit 41.
Is determined. The central processing unit 41 performs predetermined operation processing for transitioning to the maintenance mode to the peripheral device 42 and the like, and then outputs an optical signal output signal 48 for optical signal power measurement for a certain period of time. 35
Then, the optical transmission and reception unit 32 is driven, and a drive signal for measuring the power level of the optical signal can be sent to the optical field bus 5.

Here, the optical signal for measuring the power level of the optical signal is a continuous light which is a driving method which can be measured by an optical power meter 7 which is a general measuring instrument, or an ON-O.
Driven as a continuous rectangular wave with a constant FF ratio. The continuous rectangular wave optical signal used here is irregular ON like data.
Since the peak power of the optical signal having the -OFF ratio cannot be measured by the general optical power meter 7 due to the response, the ON-OFF ratio
It measures the average optical power level of a signal with a constant ratio. In general, in a bus system, one common bus communication line is shared and used by the bus subscriber stations, and the bus subscriber stations communicate with each other sequentially according to a procedure predetermined as a system between the subscriber stations. The station that has acquired the right to exchange information can transmit information. Therefore, for example, if the optical transmission unit 34 fails and remains lit for some reason, this bus line (optical field bus 5) may be occupied by the failed optical signal, which may hinder communication with other normal devices. There is. For this reason, the optical transceiver 32
Often has a built-in continuous light emission prevention function.
In such a case, a continuous rectangular wave is used as the optical signal for measuring the optical signal power for a certain period of time.

Also, when the operation switch 46 is operated, the central processing unit 41 transmits a continuous wave or ON-OFF signal to the optical transmitting / receiving unit 32 in the same operation as described above to measure the optical power level. A drive signal 48 of a continuous rectangular wave signal having a constant ratio is transmitted. Therefore, in the optical signal transmitting / receiving unit 32,
As in the case of normal communication, a continuous light or continuous rectangular wave optical signal is transmitted at the peak power level, so that the power level of the optical signal arriving by the optical power meter installed at the far end of the optical path can be measured. it can.

Next, a description will be given of a transmission frame configuration used in an optical fieldbus device according to an embodiment of the present invention. In FIG. 3, the symbols of each part in the transmission frame have the following meanings. That is, a bit pattern for initializing a demodulation circuit such as a PR (preamble) receiving modem SD (start delimiter) frame start DLL (data link layer) frame type information destination destination address source address FAS (field bus Access sublayer) FMS (Fieldbus message specification layer) Data transmission request that requires confirmation with the partner station Read / Write Data length and index number of this data Data length and subindex number of this data FCS (Frame check sequence) ) DLL header and data for FAS and FMS error check. In general, parity check for CRC error control End of ED (end delimiter) frame Control commands for individual devices, such as a command to enter maintenance mode, are transmitted in DLL (data link layer) and FMS (fieldbus message specification layer). Notified.

The frame structure of data transmitted on the optical field bus 5 will be described. The modem unit 35 receives the transmission frame transmitted from the optical field bus 5, and
The demodulation circuit such as the receiving modem is initialized (synchronized) with the preamble Pr signal placed at the beginning, the start of the frame is known by the next start delimiter SD, and the data link layer DL
L indicates frame type information, transmission destination address information,
Detects information such as the source address. This information is transmitted to the central treatment unit 41 via the internal bus 45, and the central treatment unit 41
When detecting that the information is addressed to its own station from the transmission destination address information, it knows that it is individual device data from the frame type information. If the next fieldbus message specification layer FMS is a data transmission request that requires confirmation with the partner station and the read / write information is write information, the next index number, its data length and subindex number The data length is notified to the central treatment device 41 and is temporarily stored. An error check is performed to determine whether or not the data received in the next transmitted frame check sequence FCS has been normally received, and the end of the transmission frame is detected by the end delimiter ED. When the transmitted data can be normally received and the read / write information is the write information, the data and sub-data specified by the index number and the data length are written to the specified location of the memory 43.

When the written data content is in the maintenance mode, the central processing unit 41 shifts to the maintenance mode and calls a maintenance mode program which is manufactured in advance and loaded in the memory 43.
A continuous wave or continuous rectangular wave signal output for a fixed time is output.

As described above, according to the present invention, the means for shifting the central processing unit of the slave unit to the maintenance mode, and in response to this shift, the shift from the slave unit to the master unit for a certain period of time.
Means for transmitting an optical signal for measurement, and means for receiving the optical signal for measurement and determining whether or not the optical signal is at or above a predetermined level. Signals can be output for a certain period of time to facilitate inspection of the optical transmission system. In addition, the technology according to the present invention can be applied not only to the optical field bus 5 and the optical field bus device 3 connected to the bus, but also to an optical transmission line by 1: n or 2: n star coupling and a connection to this optical transmission line. The present invention can also be applied to a light field device 9 to be used.
As a result, it is not necessary to perform the inspection work by removing the optical fiber even in a place where the installation environment condition on the site device side is bad, so that high reliability can be secured.

[0030]

As described above, when the optical fieldbus device according to the present invention is used, an optical signal for maintenance is output to the field device when an abnormality of the optical transmission system is found and the system is inspected. So you can
It is possible to determine whether or not the light emitting element is outputting a predetermined optical signal power without removing the transmission / reception unit of the field device. In addition, it is not necessary to connect a separate light source when inspecting the optical fiber and the optical splitter for deterioration of light and increase in light loss due to dirt, etc. It is possible to avoid the problem of measurement accuracy caused by the possibility of adhesion and the attachment / detachment error, and to facilitate the inspection of the optical transmission system.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram using an optical fieldbus device as one embodiment of the present invention.

FIG. 2 is a block diagram of an optical fieldbus device as one embodiment of the present invention.

FIG. 3 is a diagram illustrating a frame configuration of a transmission signal.

FIG. 4 is a system configuration diagram using a conventional optical field device.

FIG. 5 is a block diagram of an optical fieldbus device according to the related art.

[Explanation of symbols]

 1 Upper device 2, 8 Optical branching device 3, A1, A2, A3 ... An optical fieldbus device 31, 91 Interface circuit 32 Optical transceiver 33 Receiver 34 Transmitter 35 Modem 36 Logical OR device 37, 38, 48 Signal 41 Central processing unit 42 Peripheral device 43 Memory unit 44 I / O unit 45 Internal bus 46 Switch 5 Optical field bus 51,52,6,61,62 ... 6n Optical fiber 7 Optical power meter 9, B1, B2, B3・ ・ Bn Optical field device Pr preamble SD start delimiter DLL data link layer FAS fieldbus access sublayer FMS fieldbus message specification layer FCS frame check sequence ED end delimiter

Claims (3)

[Claims] 1. An optical fieldbus device for connecting a master unit and a slave unit via an optical communication path, means for shifting a central processing unit of the slave unit to a maintenance mode, and in response to the transition, the slave unit Means for transmitting an optical signal for measurement during a certain period from the side to the master unit, and means for receiving the optical signal for measurement and determining whether or not the optical signal is at or above a predetermined level And an optical fieldbus device. 2. The fieldbus device according to claim 1, wherein a command is transmitted from the master unit via the optical transmission system, so that the central processing unit of the slave unit is shifted to the maintenance mode. Optical fieldbus equipment. 3. The optical fieldbus device according to claim 1, wherein the central processing unit of the slave unit is shifted to a maintenance mode by an operation switch provided on the slave unit side.