CNCSimulator Pro

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11.2.1. NULL variables

Fanuc controls allow the use of null (undefined) variables. They evaluate to 0 (zero) in some situations and in others, to nothing. We find this behavior unsafe and confusing and therefore we ask our users to always give variables a defined value before using them.
 
Example:
 
#100 = 10
 
G00 X#100 Y#101
 
This will make a Fanuc ignore the Y value as #101 has not been defined (is NULL). In the simulator you will see the following alarm message.
 
 
To fix this, just make sure to assign a value to any variable you are using in the program.
 
 
 
The only time we allow uninitialized variables in the simulator is when comparing them to #0 (see Conditional Expressions). In this way, as #0 always is NULL, you can check if a variable is initialized or not before using it.
 
Example of allowed use of a NULL variable:
 
IF[#501EQ#0] THEN #501=0
 
This block will set variable number 501 to 0 if it is not already initialized. This is useful with permanent variables, to see if they have been initialized by a previous program, or manually.
 
Please note that the #0 variable has to be the last variable in the expression. This will not work:
 
IF[#0EQ#501] THEN #501=0