Basic Characteristics RAPID

errnum Error number
Description
Examples
Errnum is used to describe all recoverable (non fatal) errors that occur during program
execution, such as division by zero.
If the robot detects an error during program execution, this can be dealt with in the error
handler of the routine. Examples of such errors are values that are too high and division
by zero. The system variable ERRNO, of type errnum, is thus assigned
different values depending on the nature of an error. The error handler may be able to
correct an error by reading this variable and then program execution can continue in
the correct way.
An error can also be created from within the program using the RAISE instruction.
This particular type of error can be detected in the error handler by specifying an error
number as an argument to RAISE.
reg1 := reg2 / reg3;
.
ERROR
IF ERRNO = ERR_DIVZERO THEN
reg3 := 1;
RETRY;
ENDIF
If reg3 = 0, the robot detects an error when division is taking place. This error,
however, can be detected and corrected by assigning reg3 the value 1. Following
this, the division can be performed again and program execution can continue.
CONST errnum machine_error := 1;
.
IF di1=0 RAISE machine_error;
.
ERROR
IF ERRNO=machine_error RAISE;
An error occurs in a machine (detected by means of the input signal di1). A jump
is made to the error handler in the routine which, in turn, calls the error handler
of the calling routine where the error may possibly be corrected. The constant,
machine_error, is used to let the error handler know exactly what type of error
has occurred.
RAPID Reference Manual 7-errnum-1