TN 1206 Understanding and resolving logger informational messages showing repetitions of “Partially Connected” and “Connected”

Description

This article from InSource shows...

• Author: Peter Farrell
• Published: 12/16/2021
• Applies to: Application Server all versions

Details

If, in a redundant IO environment, the System Management Console is filling with informational level messages which show a redundant topic partially connected and then connected, you may need to consider changing the configuration and/or architecture.

The logger messages may look similar to the following.

Status of Backup DI source [MyRedundantIOSource] is Partially Connected

Status of Backup DI source [MyRedundantIOSource] is Connected

There are a couple of reasons that you may see the repeating informational messages advising of a partial connection and then connection.

1. You may have more then one PLC (topic/device group) included within a single redundant IO object. The problem with such an architecture is that if one of your PLCs is down, the object will then show a partially connected status.
2. You may not have defined a ping item for your topic/device group. Under this circumstance, the system will choose a ping item which may itself not be a good choice and become unavailable. You should always specify a ping item.

Shown below in the screen shot is a configuration of a redundant DI Object which includes more than one PLC and no ping items defined for the scan groups.

If possible, each Redundant DI Object should contain only a single PLC/Device/Scan Group and you should identify a PLC IO item which can be used for each device group/scan group defined for that PLC.

In the example shown below, the configuration/architecture has been changed such that the object hosts only a single PLC and each scan group has been configured for a ping item, which is a PLC item reference. Failure to add a ping item can result in unnecessary failover conditions.