3502
Optical Chopper System
32
8.
To exit the application, either close the window or select ‘
Exit’
from the ‘
File’
menu.
4.3
USB Communication
To control the Model 3502 Optical Chopper remotely without using the GUI
application, commands can be issued directly over USB using the Newport USB
library. The API is described in detail in the document ‘
Chopper USB Libraries API
User’s Manual.pdf
’. This file is installed in the ‘
Docs
’ folder. After consulting this
document, the best way to become acquainted with the procedure for controlling
the Model 3502 Optical Chopper programmatically is to review the provided C#
and LabVIEW examples.
4.4
Command Index and Conventions
In the brief command index below and detailed command descriptions that follow
in the next subsection several conventions are used.
Some commands may be used to set and query an operating parameter. For
example, the PHS command can be used to set the chopping phase (PHS900) or
to read the value of the phase (PHS?). If a command allows querying, it will be
followed by a ‘?’. If a command is not a query, there will be no response from the
Chopper Controller.
A bracket pair ‘[ ]’ indicates that the command accepts a data value. Data ranges
are given in parentheses ‘( )’. Do not use a decimal point or comma in data passed
to the Chopper Controller this way. For example, to set the chopping frequency
to 1.23 kHz, send the command OSC123000. To set the phase to -90 degrees,
send the command PHS-90. Note that data returned from the Controller will have
decimal points included.
Multiple commands on a single line must be separated by a semicolon ‘;’.
Table 3 below summarizes all commands.