Analog I/O Isolation
All analog inputs/outputs to/from the DCS (including temperature signals) used for close loop control shall be provided with individual isolator (galvanic or optical). Each isolator shall provide 3-port isolation between input, output and power supply circuits, thus eliminating the need for high integrity earth and giving floating voltage signal that can be grounded at any point.
Each isolator shall be replaceable on-line without disconnecting the wiring between the DCS and field instrument, and without affecting other signals in the system.
If intrinsic safety signals are specified then active barriers shall be quoted as alternative to the DCS isolators.
All other remaining analog inputs (including T/C and RTD inputs) used for monitoring purpose shall have optical or galvanic isolation between the system and field signals and between field signals and power supply

模拟I/O隔离
所有输入集散控制系统或从集散控制系统输出（包括温度信号）用于封闭环路控制的模拟，将由单独的隔离器提供（直流电的或光学的）。每一个隔离器将在输入，输出和电源电路之间提供三个隔离接口，这样避免了高压完全接地的必要，并且提供了在任意一点接地的流动电压信号。
每个隔离器在不切断集散控制系统和专业器械的线路情况下可以被在线替换，而且不影响系统的其他信号。
如果内部安全信号被指定，那么现行障碍可以作为集散控制系统隔离器的替代。
所有用于监控的其他剩余模拟输入（包括T / C和电阻投入）在系统和专业信号之间，以及专业信号和电源之间，有光学的或直流电隔离。