JP3890587B2 - Field device communication device in distributed control system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is effective for internal parameters in functional blocks of intelligent field devices, in particular, field devices conforming to the Foundation Fieldbus specification, in which internal parameters are set and referred to by digital communication with a host controller. The present invention relates to a communication device for accessing.
[0002]
[Prior art]
With the development of smart sensors, the intelligence in field devices has expanded and various functions have been incorporated. Along with this, there are many parameters in the field device other than the input / output values for control, and it is desired to provide the user with means for efficiently accessing these parameters.
[0003]
In the conventional smart sensor communication technology, the access to internal parameters is very slow with respect to the control cycle of the distributed control system (hereinafter referred to as DCS) due to the problem of transmission speed. Limited to calibration and maintenance applications. Therefore, with the conventional sensor parameter communication function, periodic communication is required only by executing communication according to an on-demand request from a sensor parameter tuning function on a host control device such as an engineering workstation (hereinafter referred to as EWS). Was not.
[0004]
A system configuration in the case where this on-demand communication is executed by an individual input / output function of remote I / O communication in DCS will be described with reference to FIG. Reference numeral 1 denotes an EWS connected to the Ethernet 2 for performing various parameter tuning of the smart sensor. Reference numeral 3 denotes a gateway connecting the Ethernet 1 and the control bus 4, 5 denotes a field control station (hereinafter referred to as FCS) connected to the control bus 4, and 6 denotes a smart sensor connected to the FCS via the remote I / O bus 7.
[0005]
An interface module 8 relays the smart communication with the FCS via the remote I / O bus 7, and relays the setting and reference of the internal parameters of the smart sensor 6 by the FCS.
[0006]
In such a configuration, the parameter setting work from the EWS tuning screen is accessed to the internal parameters through the path of Ethernet 2, gateway 3, control bus 4, FCS 5, remote I / O bus 7, and interface module 8. The internal parameter reference operation follows the reverse path and is displayed on the EWS tuning screen.
[0007]
For the communication between the FCS 5 and the interface module 8 that are performed interactively via the remote I / O bus 7, an individual input / output function of remote I / O communication by the FCS 5 is used. In this case, parameter setting / referencing is performed separately for each parameter. Therefore, if the access frequency increases, the communication load increases, and processing takes time.
[0008]
In recent years, the field network specifications have been established by Foundation Fieldbus, which aims to become a globally unified standard by the Fieldbus Foundation, which enables access to field devices via high-speed digital communications. In this standard, functional blocks are incorporated in the field device in software, and it is possible to configure a control loop by the field device itself.
[0009]
For this reason, it is desirable to operate and monitor various parameters for realizing the function of the field device from the DCS host device (operator console) with respect to the function block in the field device, which is faster and more periodic than before. A communication means is needed.
[0010]
[Problems to be solved by the invention]
In communication using the conventional individual input / output function described with reference to FIG. 2, it is difficult to ensure a constant periodicity of communication. This is because the communication path is small relative to the number of field devices supported by DCS, so it is dynamically allocated according to the number of user requests, and if there are many requests, the system waits for a long time or is rejected. By.
[0011]
Further, if communication using the individual input / output function that has been used on demand until then is executed periodically, the load on the FCS and the load on the remote I / O bus increase as compared with the state in which only the normal control operation is performed. It is expected.
[0012]
For these reasons, it is considered that the online communication function of remote I / O communication capable of high-speed fixed-cycle processing, which has been used only for conventional input / output data communication, is used for communication for tuning internal parameters of field devices. It is done.
[0013]
However, there is a data size problem when using this function. That is, the internal parameters in the functional blocks of the Foundation Fieldbus standard field device are handled as structure data in which a plurality of parameters are collected as one data, and therefore there are some which have a size of several tens of bytes.
[0014]
On the other hand, the largest data that can be handled by the channel for one I / O point of the online communication function is the floating point data with status, which is up to 5 bytes. Therefore, it is difficult for DCS to handle this structure data in the same way as conventional input / output data.
[0015]
[Means for Solving the Problems]
In order to achieve such a problem, the invention according to claim 1 of the present invention is:
A field control station (FCS) connected to a host system via a control bus, a fieldbus communication interface module that performs communication with the FCS via a remote I / O bus, and the fieldbus communication via a fieldbus In a field device communication apparatus used in a distributed control system including a field device that performs communication with an interface module,
The field device has a function block inside, accepts setting / reference communication of the internal parameter of the function block, and returns a plurality of internal parameters as one structure data when receiving the reference communication Comprising
The fieldbus communication interface module receives an online communication channel for performing high-speed fixed-cycle communication with the FCS via the remote I / O bus, an internal parameter information table of the field device, and a setting request from the FCS. A setting communication mechanism unit that executes communication for setting the internal parameters of the field device, and performs reference communication of the internal parameters of the field device at regular intervals, decomposes the received structure data, and the internal parameters A reference communication function unit that refers to the information table and stores it in the online communication channel ,
The internal parameter information table defines internal parameters and parameter identifiers specific to structure data, structure data position information indicating a position in the structure, and online communication channel information indicating an online communication channel number. To do.
[0016]
The invention according to claim 2 is characterized in that the field device conforms to the Foundation Fieldbus specification and the structure data is referred to by using a View Object function by a parameter descriptor.
[0017]
According to a third aspect of the present invention, the FCS includes an online communication function for executing fixed-cycle communication with the fieldbus communication interface module via the remote I / O bus, and a functional block map of the field device. And a face plate block function provided as operation / monitoring information for the host system .
[0019]
DETAILED DESCRIPTION OF THE INVENTION
To summarize the features of the present invention, first, regarding fieldbus communication,
(1) Reference communication to internal parameters is performed at regular intervals.
(2) A communication load is minimized by using a view object having a standard function in a functional block that accesses a plurality of internal parameters as structure data.
Regarding FCS remote I / O communication,
(1) Uses the online communication function, handles internal parameters other than input / output data in the same way as conventional I / O, and does not increase the load on the FCS and remote I / O bus even when executing high-speed, fixed-cycle communication. .
(2) Information related to the view object is held in the fieldbus communication interface module, and arbitrary internal parameters of the view object are stored in the online communication channel.
[0020]
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system configuration diagram showing an embodiment of a DCS to which the system of the present invention is applied. Elements described in FIG. 2 are denoted by the same reference numerals. Reference numeral 10 denotes an information command station (ICS) for operating and monitoring the process, and communicates with the FCS 5 via the control bus 4.
[0021]
Reference numeral 11 denotes a fieldbus communication interface module which forms a main part of the present invention, which performs online communication with the FCS 5 via the remote I / O bus 7 and also conforms to the Foundation Fieldbus specification via the fieldbus 12. 13 to communicate.
[0022]
Reference numeral 15 denotes a functional block formed in software in order to realize a specific function of the field device 15, and a plurality of internal parameters 15 are set therein. Reference numeral 16 denotes structure data for collectively referring to the plurality of internal parameters as one data. This structure data can be referred to by using View Object, which is a standard function in the function block.
[0023]
In the fieldbus communication interface module 11, reference numeral 17 denotes a reference communication function unit, which gives a reference command a in the form of a parameter descriptor indicating structure data to the functional block of the field device 13 via the fieldbus 12 at a fixed cycle. Information b of the structure data 16 is acquired by the view object and stored in the structure data holding unit 18. The load on the fieldbus 12 can be reduced to several to several tens of times by a communication device using a parameter descriptor reference command and structure data acquisition.
[0024]
In the fieldbus communication interface module 11, reference numeral 19 denotes a setting communication function unit, which passes internal parameter setting information c commanded from the ICS 10 via the FCS 5 to the function block 14 via the fieldbus 12.
[0025]
Further, in the fieldbus communication interface module 11, reference numeral 20 denotes an online communication channel, which includes a plurality of communication channels assigned numbers. 21 is an internal parameter information table. As shown in 21a, the contents of the first layer are parameter identifiers and the second layer is structure data position information. Online communication channel information indicating a number is defined.
[0026]
Each of the plurality of internal parameter information held in the structure data holding unit 18 is decomposed based on the definition of the internal parameter information table 21, mapped to a predetermined number block of the assigned online communication channel 20, and stored. The Each channel of online communication is composed of 5 bytes as described above, and this size is sufficient to store each of the decomposed internal parameters.
[0027]
In FCS 5, reference numeral 22 denotes a faceplate block, which has a mapping of the function block 15 of the field device 13, and is online by the online communication function of the fieldbus communication interface module 11 via the remote I / O bus 7 at high speed and in a fixed cycle. Communication with the communication channel 20 is performed, and internal parameter information obtained by this communication is reflected in the internal parameter information of the faceplate block.
[0028]
This faceplate block can be operated / monitored by the operation / monitoring screen 24 on the ICS 10 side, like other function blocks inside the FCS, and internal parameter information can be grasped in real time on the ICS 10 side. .
[0029]
【The invention's effect】
As is apparent from the above description, the present invention has the following effects. (1) It is possible to provide an easy reference means from DCS at a high speed and with a constant cycle for the internal parameters of the field device.
(2) The use of the online communication function does not increase the load with respect to the normal control operation of the FCS compared to the case of using the conventional individual input / output communication function. (3) By structure data reference method using parameter descriptor and View Object,
It is possible to minimize the fieldbus communication load and flexibly assign internal parameters necessary for operation / monitoring to limited online communication channel resources.
[0030]
[Brief description of the drawings]
FIG. 1 is a system configuration diagram showing an embodiment of a DCS to which an apparatus of the present invention is applied.
FIG. 2 is a system configuration diagram showing an example of a DCS to which a conventional apparatus is applied.
[Explanation of symbols]
4 Control bus 5 Field control station (FCS)
7 Remote I / O bus 10 Information command station (ICS)
11 Fieldbus communication interface module 12 Fieldbus 13 Field device 14 Function block 15 Internal parameter 16 Structure data 17 Reference communication function section 18 Structure data holding section 19 Setting communication function section 20 Online communication channel 21 Internal parameter information table 22 Face plate Block 23 Online communication function 24 Operation monitoring screen

Claims (3)

A field control station (FCS) connected to a host system via a control bus, a fieldbus communication interface module that performs communication with the FCS via a remote I / O bus, and the fieldbus communication via a fieldbus In a field device communication apparatus used in a distributed control system including a field device that performs communication with an interface module,
The field device has a function block inside, accepts internal parameter setting / reference communication of the function block, and returns a plurality of internal parameters as one structure data when reference communication is accepted Comprising
The fieldbus communication interface module receives an online communication channel for performing high-speed fixed-cycle communication with the FCS via the remote I / O bus, an internal parameter information table of the field device, and a setting request from the FCS. A setting communication mechanism that executes communication for setting the internal parameters of the field device, and performs reference communication of the internal parameters of the field device at a fixed period, and decomposes the received structure data and the internal parameters A reference communication function unit that refers to the information table and stores it in the online communication channel ,
The internal parameter information table defines internal parameters and parameter identifiers specific to structure data, structure data position information indicating a position in the structure, and online communication channel information indicating an online communication channel number. field device communication apparatus in a distributed control system. The field device communication apparatus according to claim 1, wherein the field device conforms to a Foundation Fieldbus specification, and the structure data is referred to by using a View Object function based on a parameter descriptor. The FCS uses an online communication function for performing periodic communication with the fieldbus communication interface module via the remote I / O bus, and a functional block mapping of the field device as operation / monitoring information for the host system. The field device communication apparatus in the distributed control system according to claim 1, further comprising a face plate block function to be provided.

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