HA243821
Issue 5 Mar 98
Section5
Page 5 - 17
MODEL 346 INSTALLATION AND OPERATION MANUAL
5.6 DERIVED VARIABLES (Cont.)
EXAMPLE
To calculate the average of the measured inputs of channel 1 to channel 6 and output it to channel 7.
Note...
Derived Variables operate on the engineering units of an input channel. If a 4 to 20 mA input is measured as 1
to 5 Vdc and scaled 0-1000 kPa the DV calculations use values of kPa.
5.6.2 MATHS FUNCTIONS
The following functions are scrollable in the DV configuration menu:
Off
Used to turn a DV off, all DVs are initially in the off state.
Add
Add input 1 to input 2
Subtract
Subtract input 1 from input 2
Divide
Divide Input 1 by input 2. Should input 2 be, or become 0, the output goes to 99999.
Multiply
Multiply Input 1 by input 2
Lin. Slope
ax + b function where x is input 1, ‘a’ (slope) is input 2 and b, (offset), is input 3.
High select
High Select. The value is the higher of IN1 or IN2 values.
Low select
Low Select. The value is the lower of IN1 or IN2 values.
High peak
High Peak. The value is the highest value of IN1 measured since the function was last reset (by
action equation). Function resets to current value.
Low peak
Low Peak. The value is the lowest value of IN1 measured since the function was last reset (by action
equation). Function resets to current value.
(Continued)
Ch7
DV1
Ch1 + Ch2
DV4
Ch1 + Ch2 + Ch3 + Ch4
Div
DV6
Ch7 =
Ch1 + Ch2 + Ch 3 + Ch 4 + Ch 5 + Ch 6
6
Constant = 6
Ch1
Ch2
Ch3
Add
DV2
Ch3 + Ch4
DV3
Ch5 + Ch6
DV5
Add
Ch4
Ch5
Ch6
Add
Add
Add
