Isa ISO Instrumentation Codes

Overview

Engineering reference data for Isa ISO Instrumentation Codes in process control.

Key Formulas

PID Controller

$u(t) = K_p e(t) + K_i \int e(t)dt + K_d \frac{de}{dt}$

Proportional-Integral-Derivative control.

Transfer Function

$G(s) = \frac{K}{\tau s + 1}$

First-order system.

Variables

ISA Code Reference Table

ISA Code Construction Examples

ISA codes are constructed by combining the process variable symbol with the instrument function symbol. A unique identification number is then appended.

Example: Level Indicator

A level indicator combines:

• L → Level (process variable)
• I → Indicator (instrument type)

Resulting code: LI

For a specific instance (e.g., level indicator #8): $\text{ISA Code} = \text{LI } 08$

Common Code Patterns:

Suffix Letters

Additional suffix letters may be added after the function letter to denote specific capabilities:

References

• Original Source