Control Application Process (Cap) Block; Enhanced-Analog Input Function Block (E-Ai) - ABB 266 Operating Instruction

266 Models - FOUNDATION Fieldbus
Control Application Process (CAP) Blocks

Enhanced-Analog Input Function Block (E-AI)

Overview
The Analog Input receives in input variables produced in the Transducer Block via the selected CHANNEL. It is possible that some
transmitters have more Transducer Blocks or more variables produced within one Transducer Block. The CHANNEL setting allows
the user to select the desired variable to be used in input for the AI.
Block diagram
Description
Transducer scaling (XD_SCALE) is applied to the value from the channel to produce the FIELD_VAL in percent. The XD_SCALE
units code must match the channel units code (if one exists), or the block will remain in O/S mode after being configured. A
block alarm for units mismatch will be generated. The OUT_SCALE is normally the same as the transducer, but if L_TYPE is set
to Indirect or Ind.Sqr.Root, OUT_SCALE determines the conversion from FIELD_VAL to the output. PV and OUT always have
identical scaling.
OUT_SCALE provides scaling for PV. The PV is always the value that the block will place in OUT if the mode is Auto. If Man is
allowed, someone may write a value to the output. The status will prevent any attempt at closed loop control using the Man
value, by setting the Limit value to Constant.
The LOW_CUT parameter has a corresponding "Low cut-off" option in the IO_OPTS bit string. If the option bit is true, any
calculated output below the low cut-off value will be changed to zero. This is only useful for zero based measurement devices,
such as flow.
The PV filter, whose time constant is PV_FTIME, is applied to the PV, and not the FIELD_VAL.
34 OI/266/FF/ADD-EN Rev. B | 2600T Series Pressure transmitters