Difference between revisions of "MC-Basic:ONERROR"
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Latest revision as of 02:30, 25 April 2017
| Language: | English • 中文（简体） |
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The ONERROR statement is used to trap and process both synchronous and asynchronous errors in a task. A synchronous error is one caused by the user task, and is detected by the interpreter, while an asynchronous error is not associated with a specific line of program code. Examples include position following errors. Errors not trapped by a TRY/FINALLY mechanism within the task are trapped by ONERROR. When an error is trapped, the specified error processing code is run and the task is stopped. The task is in state 4. Task execution is resumed by explicitly entering the CONTINUETASK command within the error processing code.
 | NOTE |
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SYNCHRONOUS errors stop a task that catches them by means of "onerror" so that a "continuetask" is needed |
Syntax
Program 'Beginning of program
<Code>
OnError 'Start of OnError block
{catch <error number X>
<code to execute when error X occurs>}
{catch <error number Y>
<code to execute when error Y occurs>}
{catch else
<code to execute for all other errors>}
End OnError 'End of OnError block
<Code>
End Program 'End of program
Availability
All versions
Type
NA
Range
NA
Units
NA
Default
NA
Scope
Task
Limitations
ONERROR traps only errors associated with the task in which they are defined.
Nesting of ONERROR is not allowed.
Examples
OnError
catch 3017
print "Position Following Error"
System.motion = 0 'Stop all motion
killtask task2.prg
End OnError