Keithley SourceMeter 2400, User Manual

Page: 406 / 594

2400 Series SourceMeter
®
User’s Manual SCPI Command Reference 18-25
Description
This command can be used to select a math expression that already
exists (built-in or user-defined). Math expression names that already
exist can be listed using the :CATalog? command. The actual math
expression can be read using the :MATH? command. The built-in math
expressions (except POWER) require a two-point sweep in order to per-
form the calculation. The “Program fragments” show how to configure
the SourceMeter for these math expressions.
When you want to create a new user-defined math expression, perform
the following steps in order:
1. If desired, assign units to the calculation result. (See “:UNITs
<name>,” page 18-29 .) Units is stored for the calculation.
2. Assign a name to the expression (using up to 10 ASCII characters)
using this command.
3. Define the expression using the: DEFine or EXPRession command.
The new expression is the one that will be presently selected.
Math expression errors:
+801 “Insufficient vector data” — Returned to idle before acquiring
enough data to fully populate the vector. A CALC1 result is not
built.
+804 “Expression list full”
— Attempted to create a new expression
name when the list (catalog) is full. The maximum number of user-
defined expression names is five.
+805 “Undefined expression exists” — Attempted to create a new
expression name while a previous expression name remains unde-
fined. Remember, after creating a name, you have to define the
expression.
+806 “Expression not found” — Attempted to delete a named math
expression that cannot be found.
+807 “Definition not allowed” — Attempted to define an expression
that has not been previously named.
+808 “Expression cannot be deleted” — Attempted to delete one of the
built-in math expressions. (See “:DELete[:SELected] <name>,”
page 18-29 .)
+809 “Source memory location revised”
— Occurs when a
:SOURce:MEMory sweep location references an expression that
no longer exists.
+811 “Not an operator or number” — Defined a null math expression
by not using a valid operator or number.
+812 “Mismatched parenthesis” — Number of open parentheses must
be the same as the number of closed parentheses. For example,
CALC1:MATH:EXPR (2*sin(VOLT) generates this error.
+813 “Not a number of data handle”
— An invalid floating point num-
ber or symbol other than VOLT, CURR, RES, or TIME appears in
the math expression.
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