By Jörg Böttcher, International P-NET User Organization, 1999.
This article briefly describes the newest VIGO version V4.0. VIGO is the easy-to-use standard driver tool for connecting standard Windows® applications to P-NET. P-NET is one of the three bus systems which are standardized within the European fieldbus standard EN 50170. Among these, P-NET is the system which needs a minimum of configuration effort. If you don't know more about P-NET, please have a look on the article "The P-NET Toolset for Building Data Acquisition Systems" or contact the adresses given under Contacts.
Version 3.0 of the Fieldbus Management System VIGO has now been in operation since the beginning of 1997, and has performed extremely well. However, as with any other software products, ideas for improvements and additional functionality are received from customers, as well as from the development team. As result, from the beginning of 1999, the new version - running under Windows®-95, Windows®-98 and Windows®-NT - is available.
From the programmer's point of view VIGO 4.0 is compatible to version 3.0. The differences mainly belong to easier use of the system. These are the main differences:
This chapter describes the main functions of the VIGO menu of version 4.0. The VIGO menu typically is used when designing a new P-NET project and during installation and service. During normal operation there is no need for the (end-)user of the system to work with VIGO itself. In this case the application program/s is/are using the VIGO functionality via OLE/ActiveX (see below) for communicating with the fieldbus system, e.g. P-NET.
After being installed, the VIGO program group consists of the VIGO main menu - valled "Vigo" - and a number of additional tools (see detailed description below) which are well known from older VIGO versions like the Monitor program or tools for downloading programs into P-NET modules:
The following screen shot shows the main menu together with a running application in the background:
MIB View shows all active projects. Remember from older VIGO versions: a project means the description of all P-NET modules including their configuration data for one P-NET application. If more than one project is defined - like in this example - these projects may belong to physically different P-NET modules or even to the same. Projects can be enabled via the Workspace window:
Furthermore, in this window all drivers which should be used are specified. The following possibilities exist:
Back to MIB View. The hierarchical structure is the same like in V 3.0. For each project all specified P-NET modules including their channels and registers can be seen. In addition, the actual version supports displaying of the current value which belongs to the selected register:
By clicking the right mouse button, additional functions, e.g. for channel configuration, can be activated:
In V 4.0, also MIB Edit - the project editor - is integrated in the main menu. Whereas MIB View only allows to have a look on the specified project structure, MIB Edit allows to define and change projects. Especially, the definition of the P-NET adress for each module and the access rights must by done by MIB Edit:
Like in former versions, when switching MIB Edit to Types view the definition of the structure of the P-NET modules can be shown, from elementary Type definitions to the definition of the whole module:
Typically, the user will not change those type definitions and when working with standard P-NET modules there is no need to do it. But there are two applications where it may make sense:
The last screen shot shows a new VIGO window, where access rights for working with the VIGO menu can be defined. Especially it is possible now, to specify passwords for several user groups:
VIGO supports both, local and remote access, by using the following alternatives (see also the driver definition via VIGO's workspace window):
The programming interface of VIGO V4.0 still consists of a standardized 32-bit OLE automation. Therefore most of the Windows® standard programs like Excel, Access, LabVIEW, VisualBasic, Visual-C++ etc. can "speak" to VIGO in a easy-to-use and effective way. For other programs which don't have an OLE/ActiveX client functionality like InTouch, additional converters, e.g. between DDE and OLE, are available. This is one of the most important advantages of VIGO: There are only a few simple steps to be done in order to establish a P-NET connection out of the application !
VIGO standard still is the most commonly used interface between VIGO and the Windows® application. The main purpose of using VIGO standard is the access to simple data of simple data types. Data access is done directly.
For using VIGO standard only the following four properties must be used:
E.g. by writing the symbolic name of a data register within a P-NET module into PhysID and reading out Value, the data will be transferred from the P-NET module into the application. That's all.
Like in version 3.0 the VIGO professional interface is used for advanced programming. Two methods of accessing data are available: direct access still works like in VIGO standard. Additionally a buffered access via the methods DoRead and DoWrite is possible. Using buffered access, the application program initiates data access, but do not stop program execution until access will be finished; instead, the program can continue with other calculations and look from time to time (polling), if data access will be finished. Like VIGO standard, all data conversion is completely handled by VIGO itself.
In addition to the VIGO professional properties and methods, RACKS/MMS related properties and methods are available. Using them, the interface between the application and VIGO is compatible to the one defined in the European RACKS project, where a common programming interface for the fieldbus systems P-NET, PROFIBUS and WorldFIP has been defined.
Like in the former versions there are several usefull tools coming with VIGO. Among those are tools for (see also first screen shot above):
Should you have any questions about VIGO or P-NET, please don't hesitate to contact one of the following adresses of the International P-NET User Organization (IPUO):
IPUO Headquarters, Denmark:
phone +45 87 200 396, fax +45 87 200 397
e-mail p-net@post4.tele.dk
IPUO Germany:
phone +49 991 270302-0, fax +49 991 270302-99
| E-Mail: services@b-plus.com |
IPUO UK:
phone +44 1491 828 200, fax +44 1491 828 201
e-mail pnet@easynet.co.uk
IPUO Portugal:
phone +351 56 412 789, fax +351 56 412 792
e-mail ajp@tecnocon.pt
IPUO Canada:
phone +1 905 840 6800, fax +1 905 840 6799
e-mail conflow@orbonline.net
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