EXFO FTB-2 - Manual (Page 212)

Preparing for Automation
202 FTB-2 and FTB-2 Pro
Getting Optimum Performance from Your Unit
Getting Optimum Performance from Your Unit
Several factors influence the data transfer rate of your unit. The information
presented hereafter will help you get the best transfer rate possible.

Output unit (RS-232, ActiveX and TCP/IP): Your unit can return results
in

linear units (for example, watts)

log units (for example, dBm)
Since internal units are linear, you will get optimal performance by
using linear units for output (no need for an internal conversion to log).
Note: You must make the choice of output unit for each instrument offering such
a feature. Refer to the user guide of each optical instrument for a list of
available commands and queries.