Section 5
Page 5 - 20
HA243821
Issue 5 Mar 98
MODEL 346 INSTALLATION AND OPERATION MANUAL
5.6.2 MATHS FUNCTIONS (Cont.)
DERIVED VARIABLE EXAMPLE
Two transmitters measuring the same flow for High/Low split range giving increased resolution and accuracy for
low flow: flow transmitter No.1 functions from 0 to 100 Litres per sec (l/s); flow transmitter No.2 functions from
100 to 1000 l/s
DV1
Low Select - Input from Transmitter No. 1 cannot go above 100 when flow is greater than 100 litres/sec
DV2
High Select - Input from Transmitter No. 2 cannot go below 0.0 when flow is less than 100 l/s (making
Scaled flow less than 0).
DV3
Add - Adds the two scaled inputs. At full flow 900 + 100 = 1000.
Ch4
Chart Range = 0 to 1000 litres per second. Source = DV3.
Transmitter 1
(0 to 100 GPM)
Transmitter 2
(100 to 1000 GPM)
Channel 1
Scaled 0 to 100
GPM
Channel 2
Scaled 100 to
900 GPM
DV1
Low select
DV2
High select
DV3
Add
Channel 4
Constant: 100
Constant: 0
