In a mission critical application, Environment Agency Wales, one of Denca’s blue chip clients had a requirement for key process data and alarms status to be made available in 4 remotely located sites and updated in as near a real-time as possible.
Our solution to this problem was to implement a Peer-to-Peer data transfer structure where each of the four CompactLogix processors contributed it’s information to a common database and this information was transferred across a fibre-optic based Ethernet-IP network connecting the 4 sites.
The data transfer was performed using Rockwell’s Producer/Consumer tag mechanism. This system requires minimal configuration and is performed as a background task by the processors. The in-built communications monitoring enables each site to determine the validity of the data it is using.
Each site is then able to use this information to determine it’s own control strategy. The information is also available for the HMI which is connected to the network and to the clients’ regional telemetry system via a Modbus link at each site. A dial-in facility is provided for remote access.
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