Varec 8300 series, Installation And Operation Manual, Page: 31 / 150

8303 Software Description
Varec, Inc. 21
4.1.8 System Tasks
System tasks include the Calendar Task, which manages Time and Date functions. Other system
tasks include utility routines for checksum calculations, diagnostics, start-up and initialization.
4.1.9 Tank Gate Interface Software Blocks
The user can configure pre-defined subprograms known as Software Blocks. These software
blocks program the Tank Gate Interface to perform various tasks, such as scaling an analog
input value, or scanning level, temperature and status information from a tank gauge. Various
software blocks are available depending on the communication module. Each Software Block
contains all the logic, constants and data to perform a particular function. Every system function
of the Tank Gate Interface is accessible via a Software Block. The user only has to add Software
Blocks using ViewRTU and then configure a few parameters in order to perform a desired
function.
4.2 Database Organization
Points are the individual instances of software blocks. Examples include Whessoe Varec 1900
(MSTX) and SCALER points. In both cases the user configures the Config parameters and is
provided real time data through the Dynamic parameters.
4.2.1 Point Format
Data parameters in the Tank Gate Interface are addressed using a “Type.Number.Parameter”
format. For example, “MSTX.02.Level” refers to MSTX Tank Gauge #2’s IEEE floating point level.
This format and corresponding fields are described below.
The TYPE field represents the Point Type. There are many different point Types in the Tank Gate
Interface, referred to generically as Tank Gate Interface Software Blocks. Some of the point types
include the COM (Communications), SYS (System), MSTX (MSTX Tank Gauge) point types. Each
Type performs a different function.
The NUMBER field represents the instance of the point type. For example, the AI point may have
up to 32 instances, which are addressed using the NUMBER field. Each instance shares the same
data structure definition, yet each point has unique data values. In the case of the AI software
block, each point manages a single input channel.
The PARAMETER field represents the items in the data structure of the point type. Examples of
parameters include Value, Status, PntRef and RawValue. This field is explained in greater detail
in the following section.
4.2.2 Parameter Description
Each parameter is defined by its Parameter Class and Data Type. The following subsections
describe Parameter Classes, Parameter Data Formats and Common Parameters.
Parameter Classes
Each parameter, such as Value or Channel, is classified as one of the following classes:
Parameter Class Description
Config Configuration parameters such as channel numbers, tags, descriptions, ranges,
operating modes, point references, constants for formulas and timing information.
Dynamic Real-time data such as the value or the status. Dynamic data is calculated or
measured during point execution scans, which occur every 250 msec.