Filter
Top Products
11
Section IV.
Controlling
the VM-502 with the SD3 SpectraDrive Controller
4.1 Description
The Princeton Instruments SD3 SpectraDrive Controller is used with the Acton
VM Monochromators in conjunction with Acton Monochromator Control
Software to provide the electronic drive for wavelength positioning, diverter mirror control and
filter positioning. The SD3 also provides the link between the monochromator and the
computer. Both USB and RS-232 are supplied as standard interfaces.
4.2 Controlling the VM-502 Monochromator with Acton Software
The Monochromator Control Software is normally installed in the directory C:\Program
Files\Acton. This directory contains the subdirectory Bin. The Bin directory contains the
executable code. There will normally be a Acton icon on the desktop that can be used
for starting the software. If this icon is not on the desktop, go to the Acton Bin directory
and start the software. When the Monochromator Control software loads, there is a main
screen with selections for operating the monochromator and various setup functions. Click on
the Operation box and a screen will come up which allows for basic control of the
monochromator wavelength. All functions of this software are described in the Monochromator
Control Software manual supplied on the Monochromator Control Software install CD.
4.3 Controlling the VM-502 Monochromator with User-Generated Software or LabVIEW
The Monochromator Control Software install disk contains a folder named Acton_SDK.
This folder contains DLLs with example code in Delphi, Visual Basic, C++ and LabVIEW as
well as a folder with examples for use of the COM interface.
4.4 Controlling the VM-502 Monochromator at the Command Level
Although it requires more programming on the user’s part, the SD3 can also be controlled with
direct commands through its USB port or RS-232 port. The same command set, listed below,
is used for both RS232 and USB.
Commands can be sent as single commands or grouped in strings of commands. All
commands are single words (contain no spaces) and all commands in a string are separated
by at least one space. Parameters, if needed, precede the command and are separated from
the command by at least one space (e.g. 546.7 GOTO).
For RS232 operation, the port setup is 9600 baud, 8 data bits, 1 stop bit and no parity. A
convenient tool for trying out this mode of operation is the program HyperTerminal supplied
with the Windows operating system. The USB port with the driver supplied also shows up as
and is treated like a com port – although a very fast one. All commands or strings of
commands must be terminated with a carriage return (0D hex). The SD3 responds to a
command when the command has been completed by returning the characters OK followed by
carriage return and line feed (hex ASCII sequence 20 6F 6B 0D 0A). The default condition is to
echo each character that is sent to the SD3 with the RS-232 interface and to not echo the
commands when using the USB interface. When sending a command or string of commands,
it is important to wait for the SD3 to complete the processing of that command string before
sending another command.