An example of such process control protection against failure is the use of two parallel control circuits. Multichannel MultiCon controllers work perfectly in such an application. In the case of problems with one loop, the second one automatically takes over the control, ensuring the continuity of control. Such a system is used by one of our customers from the food industry, where the hazard of serious defects causing production losses has been significantly reduced.
The application uses two models: CMC-99-PS32/ACM/R45/E/D8-001
Module D8 consists of 8 digital inputs which receive signals from the minimum level indicators and four maximum level indicators of the semi-product tank.
Relay output module of the R45 main recorder controls the operation of four tank filling pumps.
The controllers are connected in the Modbus network.
One of the MultiCons serves as the main controller. The second one, fed from an independent source, connected into the control circuit in the same way, continuously sends query frames using the Modbus protocol. Lack of response is interpreted as a failure of the first controller. In such a situation, the emergency MultiCon automatically assumes the controller function, ensuring the process continuity.