Database tags have two extra fields, Tag Name Column and Tag Value Column. How you fill them in depends on how the table is laid out.
1.Leave both empty for a table with one row per reading and a column for each measurement. The tag's name is the column name. PlcEcho reads the latest row.
2.Fill both in for a log table that holds name and value pairs, one row per reading — which is how most logging systems store data. For example: Tag Name Column TagName, Tag Value Column Value, and the tag's own Tag Name is the name to look for in that column, such as DB103.2.
Filling in only one of the two is reported as an error. Each tag reads its own most recent value, so tags logged at different times all show a value.
The data type matters. Choose the type the value really is. A text column holding 0.3, read as FLOAT, gives a number; one holding False, read as BIT, gives true/false. The wrong type is reported as a mismatch (see Read Error Messages).
