Analogue Input Blocks; Analogue Input Blocks, Fieldbus Foundation; Overview; Analogue Input Block Schematic - PR 5350 Configuration Manual

Foundation fieldbus

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PR5350 has 2 Analogue Input Blocks to be configured individually. The constrcution of the

Blocks is in line with the standards from FOUNDATION Fieldbus and Profibus Nutzerorgan-

isation respectively, and producer specific parameters have not been added. However, the

Analogue Input Blocks for Fieldbus Foundation and Profibus are dissimilar due to the para-me-

ter differences.

The AI block takes the manufacturer's input data, selected by channel number, and makes it

available to other function blocks at its output.

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 cutoff" option in the IO_OPTS bit string. If

the option bit is true, any calculated output below the low cutoff 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.

3.0 Analogue Input Blocks

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