Performance issue when looping on "Accept Incoming Communication" command without an available connection

Applies To:

SNAP-PAC-S1
SNAP-PAC-S1-FM
SNAP-PAC-S1-W
SNAP-PAC-S2
SNAP-PAC-S2-W
SNAP-PAC-R1
SNAP-PAC-R1-FM
SNAP-PAC-R1-W
SNAP-PAC-R1-B
SNAP-PAC-R2
SNAP-PAC-R2-FM
SNAP-PAC-R2-W

Versions Affected:

Versions affected: PAC firmware R9.5a through R9.5d
Problem is fixed in version: FW R9.5e

Resolved In Version:

Problem is fixed in version: FW R9.5e

Symptoms:

A controller's host communication—as well as all the other charts in the strategy—slow down when:

The strategy loops through (that is, repeatedly performs) an Accept Incoming Communication command.
There is no connection available to be accepted.
Any COM handle referenced by Accept Incoming Communication has a long timeout.

This is especially noticeable if the strategy is associated with an HMI that has an item that updates frequently (such as a clock or timer).

Workaround:

The default timeout for an Ethernet COM handle is 10 seconds; reduce this to 0.1 seconds, and the problem will be minimized.

In addition, add a Delay (mSec) command with a value of 1 or greater in the loop (so that the system doesn't immediately try again). The higher the value, the more the issue will be minimized.

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

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.