KB58160
Published: December 12, 2007
Revision: 3.0

Accessing a NULL pointer may cause a Stack Overflow, Bad Quality data


Applies To:

SNAP-PAC-S1
SNAP-PAC-R1
SNAP-PAC-R2
SNAP-UP1-ADS
SNAP-UP1-M64
SNAP-UP1-D64
SNAP-LCE

Versions Affected:

Problem was discovered in version: R8.0c SNAP PAC control engines, R6.0a Ultimate I/O control engines


Problem is fixed in version: R8.1a SNAP PAC control engines, R7.2h Ultimate I/O control engines

Resolved In Version:

Problem is fixed in version: R8.1a SNAP PAC control engines, R7.2h Ultimate I/O control engines


Symptoms:

If a NULL pointer variable is requested from a control engine strategy by a PAC Display project or an OPC client, a recoverable error, a Stack Overflow error, may occur.

From PAC Control, if the Debugger is open at the time the Stack Overflow error occurs, a "Stack Full" error message appears. Select the Retry button to resume normal operation. If Debugger is not open at the time the error occurs, no other indication of a problem may be apparent.

From a PAC Display project, the Event Log may log that a tag or a group of tag qualities changed to "Bad Quality." At the Opto OPC Scanner level, a "Bad Quality" message may appear for the group of data that caused the Stack Overflow error.

After the Stack Overflow error occurs, the control engine stack is cleared, and the control engine resumes normal operation.


Resolution:

Opto 22 has resolved this issue.


Questions?

Contact: Opto 22 Product Support.
Phone: 800-835-6786 or 951-695-3080
Email: support@opto22.com


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