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Problems writing a value

Created by: Robert Carlsson at: 9/17/2009 11:44 AM (3 Replies)

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9/17/2009 11:44 AM	Rate (0)
Robert Carlsson Posts: 20 Rating: (0)	Hey all! I've been developing a function block, and at the end of this function block I want to write error code to an output variable, #RET. If there were no error, I want to write the value w#16#0, if there were an error, I want the error code to be returned. Here is the code: [code] err: NOP 0 L #iReturn L W#16#8000 // Make sure the error bit is set OW T #RET // Write the error information to the RET variable SET SAVE JU exit done: NOP 0 L 0 // Make sure the RET variable indicates no error has occured T #RET SET SAVE exit: NOP 0 [/code] This only works halfway. If I have an error, the error code is written to #RET and there's nothing strange about that. But when there is no error, the execution jumps to done (and the code between err and done is never executed), but still the previous error code sticks. When getting another error code, the #RET is changed immediately, but as soon as I clear every error, nothing happens. I managed to get the things working by changing the code to this: [code] err: NOP 0 L #iReturn L W#16#8000 // Make sure the error bit is set OW T #RET // Write the error information to the RET variable SET SAVE JU exit done: NOP 0 L P##RET // Make sure the RET variable indicates no error has occured LAR1 L 0 T W [AR1,P#0.0] SET SAVE exit: NOP 0 [/code] Where the only change is after the done label. Does anyone have an explination why it didn't work with the first code? Thanks
Robert Carlsson Posts: 20 Rating: (0)
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9/18/2009 9:18 AM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 5/26/2023 Posts: 2965 Rating: (1025)	Robert Carlsson Does anyone have an explanation why it didn't work with the first code? Hello Robert I certainly do NOT have an explanation and would be just as puzzled as you are by theobserved behaviour. Both logics should give you the same result/behaviour soI wonder if either your test conditions were differentand/or there is something else "strange" going on in your Block (are you jumping back somewhere ornot jumping were you think you should jump?). I suggest you post the whole Block/test project here for evaluation.
	Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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9/18/2009 9:49 AM	Rate (0)
Aret Posts: 2348 Rating: (259)	Agree, i don't think first code is wrong (of course if #RET is of type INT) Please check this code with clean project - this can exclude any interferences from other blocks.... If you still get an error - post such reduced project here
Aret Posts: 2348 Rating: (259)
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9/18/2009 1:46 PM	Rate (0)
Robert Carlsson Posts: 20 Rating: (0)	Actually I found the reason for this strange behaviour. I had tampered with AR2 before writing to the #RET value. Restoring AR2 solved the problem. Thanks
Robert Carlsson Posts: 20 Rating: (0)
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