48 • Computer Control
NEW FOCUS, Inc.
Understanding the Command Types
There are three types of commands understood by the laser controller:
Set commands, Query commands, and Sense commands.
•
Use Set commands to set or change a value. Examples would be
commands that turn on the laser or set the operating power.
•
Use Query commands to check the user- or factory-set values of
the laser. Examples include checking the set value for the power
and checking the start wavelength for scans.
•
Use Sense commands to determine the actual values for the laser
properties at any given time. For example, you would use a Sense
command to check the actual operating current or the voltage
from the
Detector Input
.
Programming for this Laser
When programming for the laser, keep the following rules in mind.
•
For IEEE-488, issue all commands using the IBWRT function call.
To read the controller’s response, use the IBRD function call.
•
For IEEE-488, a command is not parsed until a hardware EOI is
detected (IEEE-488).
•
For RS-232 operation, end each command with a carriage
return (0x0c).
•
Numbers may contain at most 15 characters. The number 1550
will be read correctly, but the number 00000000000001550 will be
read as 15.
•
Commands that expect integer values will truncate after any
decimal point in the input. For example, if a command is issued to
run “11.76” scans, the laser will run 11 scans.
•
Only one command can be issued per line. For example, if the
controller receives
WAVE 1550;*IDN?
, it will change the
wavelength to 1550, but the Identification Query will be ignored.
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