Echelon LonPoint Application and Plug-In User Manual

Page 79

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The LonPoint Application and Plug-in Guide

8-7

Less Than

The Digital_Out network variable will be set to On
if the value from Operand 1 is less than the value
from Operand 2. Otherwise, an Off value will be
sent. Changes to the output value are affected by the
Hysteresis

value (see below).

Greater Than or Equal

The Digital_Out network variable will be set to On
if the value from Operand 1 is greater than or equal
to the value from Operand 2. Otherwise, an Off
value will be sent. Changes to the output value are
affected by the Hysteresis value (see below).

Less Than or Equal

The Digital_Out network variable will be set to On
if the value from Operand 1 is less than or equal to
the value from Operand 2. Otherwise, an Off value
will be sent. Changes to the output value are affected
by the Hysteresis value (see below).

The Math Function options determine what operation is to be performed if the
Math

function type was selected in the Function Type field. The available

options are Add, Subtract, Multiply, and Divide. The order of the equation
is always Operand 1 [plus\minus\times\divided by] Operand 2.

The Hysteresis field determines how great a difference, as a floating point
number, must exist between the analog values for the Greater Than, Less
Than

, Greater Than or Equal, and Less Than or Equal logic functions to

change the digital output. You can use this field only if the mode is set to one of
these comparison logic operations.

Selecting the Enthalpy function calculates the heat content of air, based on the
temperature and humidity. Operand 1 must be a SNVT_temp_f type, and
Operand 2

must be a SNVT_lev_cont_f type. There is no SNVT defined for

enthalpy that can be used for the Analog Output network variable, but the
Echelon user type file (ECHELON.TYP) provides a UNVT_enthalpy user type
that you can use for this purpose.

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