Deviation Indicator:

The deviation indicator, located left of the setpoint indicator, shows any error (+10 percent to -10 percent) among setpoint value and actual controlled variable value. Along with no error, the deviation pointer stays at mid-scale, in line within the setpoint index mark. The deviation indicator deflects downward if the controlled variable is lower than setpoint. The indicator deflects upward if higher. An instance of this is displays in Figure.

Figure: Deviation Indicator

The output meter is the horizontally positioned meter below the deviation and setpoint indicators. That denotes controller output signal in percent. That particular controller ranges from zero to 100 percent current. Therefore, this will correspond to an air signal for pneumatic controllers.

Snap-in tabs, above each end of the output meter, denotes the direction the last control element moves for a change in the outcome signal. Tabs generally read "open-close" for control valves and "slow-fast" for variable-speed motors, or other suitable designations.