Model 300E Carbon Monoxide Analyzer
Instruction Manual
Operating Instructions
P/N 04288 REV: A
75
6.5.2.
Current Loop Output Span and Offset Adjustment
A Current Loop Option may be purchased for each of the Analog outputs of the
analyzer. This option places circuitry in series with the output of the D-to A
converter on the Mother Board. This circuitry changes the normal DC voltage output
to a 0-20 milliamp signal with a
±
5% over/under range.
Each of the three Analog Outputs can be independently converted to current loop
operation. The outputs can be ordered scaled to any set of limits within that
0-20 mA range, however most current loop applications call for either 2-20 mA or
4-20 mA range spans.
Adjusting the signal zero and span levels of the current loop output is done by
raising or lowering the voltage output of the D-to-A converter circuitry on the
analyzer’s Mother Board. This raises or lowers the signal level produced by the
Current Loop Option circuitry.
The software allows this adjustment to be made in 100, 10 or 1 count increments.
Since the exact amount by which the current signal is changed per D-to-A count
varies from Output-to-Output and instrument–to–instrument, you will need to
measure the change in the signal levels with a separate, current meter placed in
series with the output circuit.
mADC
IN OUT
I OUT +
I OUT -
I IN +
I IN -
Recordeing
Device
MODEL
300E
See Table 5–8 for
pin assignments on
the for ANALOG
connector located on
the instruments rear
panel
Figure 6–3: Setup for Checking Current Output Signal Levels
NOTE
Do not exceed 60 V peak voltage between current loop outputs and
instrument ground.