Functions of DCS:
Based on its function, DCS has functions:
- DCS functions as a tool to control a loop system where one loop can perform several control processes.
- Serves as a substitute for manual and automatic control devices that are separated into a unit so that it is easier to maintain and use
- Data collection and processing facilities to obtain the right process output
Components of DCS:
In general, the components of DCS consist of 3 basic components, namely: Operator Station, Control Module, and I/O module.
A station operator is a place where the user monitors or monitors the running process. The station operator is used as the interface of the system as a whole or commonly also known as a collection of several HIS (Human Interface Station). The HIS form is an ordinary computer that can retrieve data from the control station. Station operators can bring up process variables, control parameters, and alarms that the user uses to retrieve operating status. Station operators can also be used to display trend data, messages, and process data.
The control module is the main part of DCS. The control module is the control centre or as the brain of all process control. The control module performs the computational process of algorithms and runs logical expressions. In general, the control module is in the form of a black box located in a cabinet or cabinet and can be found in the control room. Control modules usually use redundant mode to improve control reliability.
The function of the control module is to take an input variable that will be controlled. The variable value will be calculated. The results of this calculation will be compared with the set point. This set point is the value expected of a process. If the calculation results are different from the set point, the value must be manipulated so that it reaches the set point. Value manipulation results will be sent to the input module output and to be delivered to the actuator.
I / O Module is the interface between the control module and the field instrument. I / O module functions to handle input and output of a process value, convert signals from digital to analog and vice versa. The input module gets the value from the transmitter and provides the process value to FCU for processing, while FCU sends the manipulated value to the output module to be sent to the actuator. Each instrument field must have an alias on the I / O module. Each field instrument has a unique name on the I / O Module.