Instruction manual

Instruction Manual
760006-A
September 2001
11-10 Appendices Rosemount Analytical Inc. A Division of Emerson Process Management
Model NGA 2000 Platform
8. Adjust, if necessary, the output
value by scrolling the Zero offset:
until the output value is 0.
9. Perform the span calibration.
Change the Desired output voltage:
to 5, and scroll the Gain Factor until
the output value is 5. Skip the re-
maining steps.
10. Current calibration: perform the zero
calibration first. Set the Desired out-
put current: to 0 (no matter whether
the module is set to operate on 0 -
20 mA or 4 - 20 mA).
11. Observe and record the output
value.
12. Adjust, if necessary, the output
value by scrolling the Zero offset:
until the output value is the zero
value (0 mA).
Perform the span calibration procedure.
Change the Desired output current: to 20,
and scroll the Gain factor: until the output
value is 20.
After completing the span calibration pro-
cedure, the operator should recheck and
readjust, if necessary, the zero calibration
values.
NOTE
The measured output current or volt-
age is not measured with enough pre-
cision to do more than tell you whether
the output circuit is working or not.
Don’t try to use it to calibrate the out-
put. On the other hand, if it does show
a value, but you don’t detect one in
your monitoring device, it means that
either the output connector, or EMC
components on the I/O module are
bad, or there is an error in the wiring.
The measured signal does in fact
measure the output signal, it is not
merely calculated from the value the
output is supposed to be putting out.
Analog Output Over / Under
Limits
The analog output can be configured with
live zero/span or “clipped” zero/span by
setting the over limit and under limit of the
voltage or current output signal.
In the I/O Module Analog Output Diag-
nostics menu, select Diagnostic limits
(see Section 11-2). There will be various
current and voltage limit selections to
choose from. Edit the appropriate set of
over and under limit values that pertain to
the analog output you have selected.
The minimum current under limit is –2.0
and –6.0 while the maximum current over
limit is 25 mA. The minimum voltage un-
der limit is –90 V and the maximum
voltage over limit is 10.0 V.
Setting the under limit and over limit val-
ues is essentially setting the minimum
and maximum signal output.
The analog I/O Module is now fully oper-
able and read for use.