Basic Characteristics RAPID

RAPID Summary Error Recovery
9 Error Recovery
Many of the errors that occur when a program is being executed can be handled in the
program, which means that program execution does not have to be interrupted. These
errors are either of a type detected by the robot, such as division by zero, or of a type
that is detected by the program, such as errors that occur when an incorrect value is
read by a bar code reader.
9.1 Programming principles
When an error occurs, the error handler of the routine is called (if there is one). It is
also possible to create an error from within the program and then jump to the error handler.
If the routine does not have an error handler, a call will be made to the error handler in
the routine that called the routine in question. If there is no error handler there either,
a call will be made to the error handler in the routine that called that routine, and so on
until the internal error handler of the robot takes over and outputs an error message and
stops program execution.
In the error handler, errors can be handled using ordinary instructions. The system data
ERRNO can be used to determine the type of error that has occurred. A return from the
error handler can then take place in various ways.
In future releases, if the current routine does not have an error handler, the internal
error handler of the robot takes over directly. The internal error handler outputs an
error message and stops program execution with the program pointer at the faulty
instruction.
So, a good rule already in this issue is as follows: if you want to call the error handler
of the routine that called the current routine (propagate the error), then:
- Add an error handler in the current routine
- Add the instruction RAISE in this error handler.
9.2 Creating an error situation from within the program
Instruction Used to:
RAISE “Create” an error and call the error handler
RAPID Reference Manual 3-25