Servomex DF-310E, Operator'S Manual

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User Interface DF-310E 73
10.00 ppm area. However, the Analyzer is a 0-500 ppm unit and if the oxygen value exceeds
10.00 ppm the analog output will peg. With the expanded range option it is possible to set a
larger ppm range that will automatically rescale the analog output when the primary scale is
exceeded. In the example, the analog output is scaled over 0 - 200 ppm as soon as 10.00 ppm is
exceeded. If the oxygen level falls, the Analyzer will switch back to the original 0 - 10.00 ppm
scaling as soon as the value is below 95% of the primary scale (9.5 ppm). This scaling change
only affects the analog outputs.
When operating on the expanded range the analog output scaling information on the front panel
will change to:
                
When the asterisk is on the Expand FS line, each time the key is pressed a different full scale
value will appear. In this way it is possible to scroll through a list of selections. The expanded
range full scale value must be larger than the normal FS value, or the Analyzer will not accept
the setting. Expanded range may be turned off at any time by setting Expand FS to NU. The
zero point setup on the primary range is also used when operating on the Expanded Range.
8.4.2.4 ExpRng Relay
An alarm relay may be assigned to indicate when the optional expanded range is in effect. The
relay will be in the “Normal” state when the analog output is on the primary range scale, and will
switch to the “Alarm” state when the expanded range scale is in effect. If there are no relays
installed this option will show
NA . Since it is possible to assign more than one alarm or status
condition to any alarm relay, it is important to ensure that there are no other items assigned to
this chosen relay unless it is really desired.
8.4.2.5 CAL FREEZE
When a zero or span calibration is started CAL FREEZE holds the analog output at the last valid
oxygen value prior to the calibration. The oxygen value remains held until the calibration is
completed. This feature prevents a PLC or data acquisition system from “Seeing” a calibration.
If the PLC is used to detect alarms, a calibration could involve sampling gas sources with
concentrations above process alarm set points. CAL FREEZE may be turned off so that the
analog output operates normally (follows the oxygen value) during calibration.
8.4.2.6 IN-CAL RELAY
This is a setup feature that allows an optional alarm relay to be assigned to indicate when the
instrument is in the zero or span calibration mode. This feature may be used to signal a PLC,
DCS or other external device when the instrument is in calibration (not sending “Process” O2
data). Any relay may be assigned to IN-CAL RELAY service. If the Analyzer is not equipped
with relays, this selection will be NA. Since it is possible to assign more than one alarm or status
condition to any alarm relay, it is important to ensure that there are no other items assigned to
this chosen relay unless it is really desired.
8.4.3 Comm Port
The Comm Port Menu, selected from the Setup Menu Figure 36, is used to edit information
about the external communications port. This port operates with an 8 bit, no parity, one stop bit
setting. No hardware or software handshaking is used. See the Section on Connecting to
External Devices on page 43 for more information.