Emerson Process Management 5300 manual Signal Conversion, Direct

Reference Manual

00809-0100-4530, Rev BA July 2009

Rosemount 5300 Series

SIGNAL CONVERSION

You can set the signal conversion type with the Linearization Type (L_TYPE) parameter. You can view the converted signal (in percent of XD_SCALE) through the FIELD_VAL parameter.

FIELD_VAL =	100-------------------------------------------------------------------------------------------× (Channel Value – EU*@0%)	* XD_SCALE values
	(EU*@100% – EU*@0%)

You can choose from direct or indirect signal conversion with the L_TYPE parameter.

Direct

Direct signal conversion allows the signal to pass through the accessed channel input value (or the simulated value when simulation is enabled).

PV = Channel Value

Indirect

Indirect signal conversion converts the signal linearly to the accessed channel input value (or the simulated value when simulation is enabled) from its specified range (XD_SCALE) to the range and units of the PV and OUT parameters (OUT_SCALE).

PV	=	⎛ FIELD_VAL⎞	× (EU**@100% – EU**@0%) + EU**@0%
		⎝ ------------------------------100-⎠
			** OUT_SCALE values

Indirect Square Root

Indirect Square Root signal conversion takes the square root of the value computed with the indirect signal conversion and scales it to the range and units of the PV and OUT parameters..

PV	⎛ FIELD_VAL⎞	× (EU**@100% EU**@0%) EU**@0%
	⎝ 100 ⎠
		** OUT_SCALE values

When the converted input value is below the limit specified by the LOW_CUT parameter, and the Low Cutoff I/O option (IO_OPTS) is enabled (True), a value of zero is used for the converted value (PV). This option is useful to eliminate false readings when the differential pressure measurement is close to zero, and it may also be useful with zero-based measurement devices such as flowmeters.

NOTE!

Low Cutoff is the only I/O option supported by the AI block. You can set the I/O option in Manual or Out of Service mode only.

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