Unit conversion allows you to convert from one unit of measure to another. For example if you have Parts Per Million (PPM) in your source system (Aspen in this case) and you want to report Parts Per Billion (PPB) in OPS SQL.

There are two basic types of Aspen interfaces: direct connection, and CSV files.

The interface for direct connection (OPSSQL_ASPEN version 1.0.5) supports the use of the file unit_conversion.ini which will match units from a point of data in Aspen to the variable defined in OPS. If the units do not match, the interface can convert the values. One main thing must be in place:

• The Aspen units and the OPS units must have a definition in the unit_conversion.ini file, similar to the ones already listed in it

The interface for CSV files (OPSSQL_ASPEN_CSV version 1.0.5) has not had the unit conversion file implemented yet. However, you can do unit conversion if the units are stable - that is if the units are always PPM in Aspen and PPB in OPS. Simply run OPS and bring up edit/view variable that you want to change. Select the User Defined tab and enter the conversion factor on the line UD1. This will automatically multiply the result from Aspen by that amount before writing to OPS. Be sure you enter the right value.  For example:

UD1=1000 will cause the OPS variable to be 1000x more than the source value sent by the interface.

UD1=0.001 will cause the OPS variable to be 1000x less than the source value sent by the interface.

Please note that regardless  of any customized label the user has established for UD1, the first field (UD1) in the User Defined tab is utilized for the unit conversion factor, therefore this field should *not* be used for other purposes if the interface is installed!

Any other Aspen to OPS interface does not currently support unit conversion. KB Q10403 will help explain how to edit the unit_conversion.ini file and shows what the file looks like.