Omega Engineering CN9400 User Manual page 30

Linear Input Calibration (continued)
4–20 mA
1 ohm
from transducer
1 Power up the controller, and in response to
the prompt
select an appropriate Linear Range from
the table below.
Ensure that the Nominal Signal Span chosen is wider
than the transducer's actual signal span, and the
Nominal Scale is wider than the full scale of the
engineering units to be displayed.
Linear Range
Lin 1
Lin 2
Lin 3
Lin 4
Lin 5
2 Select
then select the process unit, °C , °F , Bar , PSI ,
Ph , or rh . If the required unit is not shown
26
select Set .
9 10 11 12 13 14 15 16
+ – + –
5Vdc 15mA L N
1 2 3 4 5 6 7 8
Outputs
Supply
Nom. Signal Nom. Scale
Span Span
0–20 mV 0 – 100
4–20 mV 0 – 100
0–20 mV 0 –1000
4–20 mV 0 – 1000
0–20 mV 0 – 2000
3 Allocate the output devices at function
as described in SET-UP , enter the configuration
into the memory and proceed as follows:
Calculate the values for the controller settings
for
4 to 7mV input from transducer is required to
display 0 - 110 units
Chose Linear Range Lin4 4-20mV = 0 to 1000 units.
INPT
HI.SC
NONE
HI.SC
SPAN
SPAN
Max. Scale
Settings
0 – 400
-25 to 400
0 to 3000
These settings should provide the correct scaling adjustment, but a
-250 to 3000
value for ZEro may need to be established by applying the lowest
0 to 3000
and highest mV input signal and recording the display offset. Check
that this is the same at each end, and enter this plus or minus value
UNIT
as a ZEro adjustment. Should there be a difference between the
two readings, a further adjustment of the SPAn setting can be made.
and using the example below
HI.SC SPAN
as a guide:
= Nominal Signal Span x required span
actual signal span
(20-4) x (110-0) = 587
(7-4)
= ( hi.SC - nominal scale span) x hi.SC
(587-1000) x 587 = -242
1000
SP1.D
Nominal Scale Span