Monitor connectivity status with a data source

The built-in discrete item, $SYS$Status, can be used to monitor the status of communications with your data source. This item is set to the following:

• 0 (zero) when communication with the data source fails.

• 1 (one) when communication is successful.

Enter the following DDE reference formula in the appropriate place in your client:

=Gateway|<Device Group>!$SYS$Status

where,

Gateway: name of Gateway Communication Driver application.

<Device Group>: exact device group defined in Gateway Communication Driver for the data source.

$SYS$Status: discrete item used to monitor the status of connectivity with the data source.

Example:

=Gateway|ModbusOverSL_FastTopic!$SYS$Status

Enter the following OPC item reference syntax when adding the item in your OPC client:

<YourLinkName>.$SYS$Status

where,

<YourLinkName>: assembly of hierarchy node names leading to a specific data source.

$SYS$Status: discrete item used to monitor the status of connectivity with the data source.

Example:

ModbusOverSL.FastTopic.$SYS$Status

Note: In case of a data source disconnection, Gateway Communication Driver attempts the number of connection retries as configured for the given data source object, and makes no more attempts afterward. Subsequently, it is up to the client to re-initiate the connection via the system item $SYS$Reconnect.