Stanford Research Systems SR860, Руководство по эксплуатации

Страница: 122 / 222

104 Programming Chapter 4
SR860 DSP Lock-in Amplifier
Real number variables may be expressed in integer, floating point or exponential formats
( i.e., the number five can be either 5, 5.0, or .5E1).
Strings are a sequence of ASCII characters within quotes (“…”).
Units
For numerical values of frequency, phase or volts, a units string may be appended to a set
command. If the unit string is omitted then the value is assumed to be the base unit, either
Hz, degrees or Volts. The accepted unit strings are:
“NV” nanoVolts “HZ” Hertz “UDEG” microDegrees
“UV” microVolts “KHZ” kiloHertz “MDEG” milliDegrees
“MV” milliVolts “MHZ” megaHertz “DEG” Degrees
“V” Volts
For example, the following commands to set the internal frequency are all equivalent
FREQ 1234.56
FREQ 1234.56 HZ
FREQ 1.23456 KHZ
Queries of f, p or v always return the value in the base units of Hz, degrees or Volts.
Enumerated Strings
Many commands have an enumerated list of allowed settings. It is possible to specify the
setting with a string instead of the integer index. Using the enumeration strings improves
the readability of your source code.
Enumerated strings can either be the substring shown in CAPS or the full string. For
example, the enumeration string “ABCDefgh” can be sent as ‘abcd’ or ‘abcdefgh’. The
string can be sent with any capitalization.
For example, the IVMD i command sets the input to either voltage (i=0) or current (i=1).
This command is specified as
IVMD(?) { VOLTage | CURRent | i }
The following commands are all equivalent ways to set the input to voltage.
IVMD 0
IVMD VOLT
IVMD VOLTAGE
These commands are all equivalent ways to set the input to current.
IVMD 1
IVMD CURR
IVMD CURRENT
The
IVMD?
query always returns the setting index i (0 or 1 in this case).