Thermo Scientific 49i, Instruction Manual, Page: 47 / 314

Operation
Range Menu
Thermo Fisher Scientific Model 49
i
Instruction Manual 3-11
Table 3-3. Default Analog Outputs in Dual Range Mode
Note All channels are user definable. If any customization has been made to
the analog output configuration, the default selections may not apply.
Auto Range Mode
The auto range mode switches the O
3
analog outputs between high and low
ranges, depending on the concentration level. The high and low ranges are
defined in the Range menu.
For example, suppose the low range is set to 500 ppb and the high range is
set to 1000 ppb (Figure 3-6). Sample concentrations below 500 ppb are
presented to the low ranges analog output and sample concentrations above
500 ppb are presented to the high ranges analog outputs. When the low
range is active, the status output is at 0 volts. When the high range is active,
the status output is at half of full-scale.
When the high range is active, the concentration must drop to 85% of the
low O
3
range for the low range to become active.
In addition, each O
3
analog output has a span coefficient. There are two
span coefficients so that each range can be calibrated separately. This is
necessary if the two ranges are not close to one another. For example, if the
low O
3
range is set to 0–50 ppb and the high O
3
range is set to 0–20,000
ppb.
Channel Pin I/O Terminal Pin Description
1 14 1 O
3
Low Range
2 33 3 O
3
High Range
3 15 5 None
4 34 7 None
5 17 9 None
6 36 11 None
Ground 16, 18, 19, 35, 37 2, 4, 6, 8, 10, 12 Signal Ground