About Tables

An RTU stores data in a set of tables. Tags are addressed by specifying the table number, then the row and column number. The table structure is replicated in the RTU database object and stored in the application database. For optimum performance, the number of tables used is kept to a minimum.

Additional tables may be added to the RTU database object on the host to store derived data such as calculated fields.

The SYSTEM table

The SYSTEM table is stored in the host database only and does not correspond to a table on the RTU. By convention, this table is given the table number 200. The SYSTEM table is commonly used to hold calculated tags, and status flags such as the communications status flag.

Viewing table properties

View table properties in the Data Sources module.

To view table properties:

Select the table and click the Expand button beside the table name to show the table details. The properties shown are:

Property	Description
Table name	Name of this table. It is conventional to allocate a table to each data type and name the table for the data type.
Table No	Table number. This can be 0 to 127 for MOSCAD tables. The SYSTEM table has table number 200.
Scan Rate	Specifies how often the system polls the table. See Setting the Table Scan Rate
Number of Rows	Number of rows in the table.
Number of Columns	Number of columns in the table
Column N	Data type of the Nth column. Tags inherit the datatype of their column.