Emerson Process Management OXYMITTER 4000 IM-106-340 - Manual (Page 62)

Oxymitter 4000
3-6
Instruction Manual
IM-106-340, Rev. 4.0
May 2006
Calibration Handshake Signal
If using an optional IMPS 4000 or SPS 4001B, the logic I/O must be
configured for calibration handshaking. Of the ten modes in Table 3-1, only
modes 8 and 9 are configured for calibration handshaking. For an Oxymitter
4000 with an IMPS 4000 or an SPS 4001B, the factory sets the default to
mode 8. In this mode, the logic I/O will be used to communicate between the
Oxymitter 4000 and sequencer and to signal the sequencer when a
CALIBRATION RECOMMENDATION indication occurs.
Recommended
Configuration 4-20 mA Signal Upon Critical Alarm
Rosemount Analytical recommends that the factory default be utilized. The
4-20 mA signal will go to the 3.5 mA level upon any critical alarm which will
cause the O
2
reading to be unusable. Customer can also select 21.6 mA as
the failure setting if normal operations cause O
2
readings to go below the zero
% O
2
(3.5 mA) level.
If the O
2
measurement is being utilized as part of an automatic control loop,
the loop should be placed into manual upon this failure event or other
appropriate action should be taken.
Calibration
Rosemount Analytical recommends utilizing an autocalibration system,
actuated by the "calibration recommended" diagnostic. New O
2
cells may
operate for more than a year, but older cells may require recalibration every
few weeks as they near the end of their life. This strategy ensures that the O
2
reading is always accurate, and eliminates many unnecessary calibrations
based on calendar days or weeks since previous calibration. When utilizing
the SPS 4001B or IMPS 4000, consider wiring some or all associated alarm
contacts.
1. CALIBRATION INITIATE. Contact from the control room to an
SPS 4001B or IMPS 4000 (one per probe) provides the ability to
manually initiate a calibration at any time from the control room. Note
that calibrations can also be initiated from a HART handheld
communicator, from Asset Management Solutions software, or from the
keypad on the Oxymitter 4000.
2. IN CALIBRATION. One contact per probe provides notification to the
control room that the "calibration recommended" diagnostic has initiated
an automatic calibration through the SPS 4001B or IMPS 4000. If the O
2
signal is being utilized in an automatic control loop, this contact should
be utilized to place the control loop into manual during calibration.
3. CALIBRATION FAILED. One contact per probe from an SPS 4001B or
IMPS 4000 to the control room for notification that the calibration
procedure failed. Grouped with this alarm is an output from a pressure
switch which indicates when the calibration gas bottles are empty.
4. 4-20 mA SIGNAL DURING CALIBRATION. The 4-20 mA signal can be
configured to respond normally during any calibration, or it can be
configured to hold the last O
2
value upon the initiation of calibration. The
factory default is for the 4-20 mA signal to operate normally throughout
calibration. Holding the last O
2
value may be useful if several probes are
being averaged for the purpose of automatic control. Unless several
probes are being averaged, always place control loops that are using
the O
2
signal into the manual mode prior to starting the calibration.