PID Output may go to previous state when switching back to auto mode

Applies To:

SNAP-PAC-R1
SNAP-PAC-R1-B
SNAP-PAC-R1-FM
SNAP-PAC-R1-W
SNAP-PAC-R2
SNAP-PAC-R2-FM
SNAP-PAC-R2-W
SNAP-PAC-EB1
SNAP-PAC-EB1-FM
SNAP-PAC-EB1-W
SNAP-PAC-EB2
SNAP-PAC-EB2-FM
SNAP-PAC-EB2-W
SNAP-PAC-SB1
SNAP-PAC-SB2

Versions Affected:

Problem affects: Firmware, all versions

Symptoms:

If you switch a PID to manual mode, change the PID Output value, and then switch the PID back to auto mode, the PID Output may revert to the previous value (the value prior to switching from auto mode to manual mode).

This issue occurs only if the switch back to auto is done quickly enough that the PID does not have time to execute a scan after changing the PID Output in manual mode. In most cases, the PID scan rate is short enough that this issue does not occur.

Workaround:

After setting the PID Output to a new value in manual mode, wait long enough to make sure the PID has executed a scan before switching back to auto mode. For example, if the PID scan rate is 1 second, then wait at least 1 second after changing the PID Output before switching back to auto mode.

Resolution:

Opto 22 is investigating this issue.

Questions?

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

DISCLAIMER

This Opto 22 Knowledge Base ('OptoKB') article is intended to provide general technical information on a particular subject or subjects and is not an exhaustive treatment of such subjects. Accordingly, the information in this OptoKB article is not intended to constitute application, design, software, or other professional engineering advice or services. Opto 22 may modify the OptoKB articles at any time. Before making any decision or taking any action which might affect your equipment, you should consult a qualified professional.

OPTO 22 DOES NOT WARRANT THE COMPLETENESS, TIMELINESS, OR ACCURACY OF THE DATA CONTAINED IN THIS OPTOKB ARTICLE AND MAY MAKE CHANGES THERETO AT ANY TIME AT ITS SOLE DISCRETION WITHOUT NOTICE. FURTHER, ALL INFORMATION CONVEYED HEREBY IS PROVIDED TO USERS 'AS IS.' IN NO EVENT SHALL OPTO 22 BE LIABLE FOR ANY DAMAGES OF ANY KIND INCLUDING DIRECT, INDIRECT INCIDENTAL, CONSEQUENTIAL, LOSS PROFIT, OR DAMAGE, EVEN IF OPTO 22 HAS BEEN ADVISED ON THE POSSIBILITY OF SUCH DAMAGES.

OPTO 22 DISCLAIMS ALL WARRANTIES WHETHER EXPRESSED OR IMPLIED WITH RESPECT TO THE INFORMATION (INCLUDING HARDWARE, SOFTWARE, AND/OR FIRMWARE) PROVIDED HEREBY, INCLUDING THE IMPLIED WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE, MERCHANTIBILITY, AND NON-INFRINGEMENT. Note that certain jurisdictions do not sanction the exclusion of implied warranties: thus, this disclaimer may not apply to you.