National Instruments FP-3000 - Manual (Page 60)

Chapter 4 Block Reference
FieldPoint FP-3000 User Manual 4-8 www.ni.com
Note Use the spreadsheet fp3kexpr.xls provided with the FP-3000 package to generate
the expression text if you have a need for the block to execute at specified times during
the day.
• x0 , x1 , x2 , x3 , x4 , x5 , x6 , x7
Provides eight unsigned 32-bit integer variables. These variable values
are persistent across block executions but are not stored in non-volatile
memory. As such, power cycling the FP-3000 will leave them with an
unknown value unless they are initialized by the user in such cases.
• last_oos
This symbol defines a boolean read-only variable in the EXPR block,
to represent whether the EXPR block’s actual mode was Out Of
Service (
OOS ) the previous time it was scheduled to execute.
User-defined variables are not allowed in the Expression block language.
However, you may (for readability reasons) choose to rename any one of
the symbols listed above using the keyword “rename.”
Keywords
• rename
This is used to rename one of the symbols listed above to a user defined
name.
For example, rename a_state_0 counter
will rename the symbol a_state_0 to counter . You can then use the
name counter in the rest of your expression. Such user-defined
names must be declared before use in the expression.
Constants
These are the constants typed in by the user in an expression.
For example, a_state_0 = 0;
In the above example, the 0 on the right-hand side of the assignment
operator ( = ) is the constant value.
User-defined constants of the form <#define XXX 123> are not
supported in the Expression block language.