Question: In process automation for applications like monitoring liquid levels in process reactors, what is the typical requirement for communication service availability, considering the data is primarily used for indicative purposes rather than automated control loops?
Option 1: High (99.999%) to ensure real-time control
Option 2: Relatively Low (99.9%) since it's not for automated control
Option 3: Moderate (99.95%) to balance reliability and cost
Option 4: Very High (100%) due to safety critical nature
Explanation: The correct answer is Option 2 because, as explained, the data from sensors in process automation for monitoring tasks (like liquid levels) is primarily used for indicative purposes (e.g., deciding when to stop a process to avoid overflow) rather than for automated control loops. This type of application does not require extremely high communication service availability, making a relatively low requirement of 99.9% sufficient. Emergency operations are typically handled locally without reliance on communication networks, further reducing the need for ultra-high availability in this context.