Conversions provide a way to quickly convert your data from the sometimes arbitrary units that your hardware device generates into more useful units, such as psi, torr, K, etc.  Conversions can be used for complex calculations, but we suggest keeping it simple and save the complex calculations for DAQFactory.  Conversions work for both input and output channels.

Entering Conversions:

To create conversions you will use the conversion table.  To access the conversion table, click on the CONVERSIONS: label under the desired connection.  The table only has two columns, the conversion name and the expression for the formula of the conversion.  To add a new conversion, click on the Add button.  Enter in a name for the conversion.  Next type in the formula.  The formula cell is an expression type cell.  This type of cell works the same as any expression box used in DAQFactory.  However, it should be noted that for all Connections except local, only channels for the given connection will be listed.

You can print the conversion table by selecting File - Print from the main menu.

Using Conversions:

A single Conversion can be used on multiple channels.  This is especially useful if, for example, you have ten pressure transducers that are all 0 to 500 psi corresponding to a voltage of 0 to 10V.  If your A to D channels were 16 bit and output 0 to 65535 corresponding to 0 to 10V, you would create a conversion with this formula to convert from the raw A to D number to psi:

 

Value / 65535 * 500

The word Value is used wherever you want to substitute the raw channel value in the formula.  You can use channels by name as well, as long as they exist on the same connection.  You can also use almost all the available functions.  The only ones that won't work are the ones that process an array (unless the conversion is for a spectrum) and the ones that modify time.  

Conversions can also be used to convert output channels.  As an example, lets make the last example an output.  If you have a pressure controller that takes 0 to 10V for a pressure setting of 0 to 500 psi, and your 16 bit D to A takes a value from 0 to 65535 corresponding to 0 to 10V, you would enter the following formula for your conversion so that you could enter psi values for set points:

 

Value / 500 * 65535

Notice how this is the reverse of the previous formula.  For outputs, we want to take useful units and convert them into the arbitrary units of your hardware.  For inputs we do the reverse.

Applying Conversions:

To apply a conversion to a channel, open the channel in the channel view, or open the channel table and find the desired channel and select the conversion from the drop down list.

Note: Your data is sacred, so logging sets give you the option of storing your data before converting or afterwards.  See the chapter entitled Logging Sets for more information.