Panametrics TMO2D, User Manual, Page: 50 / 101

Chapter 4. Basic Programming
42 TMO2D User’s Manual
Repeat this sequence for the remaining points. After you have entered the data, the display will show “Working . . .”
and return to the start of the submenu.
4.8.5 Auto Cal Parameters
You can program the TMO2D to perform an automatic calibration procedure (Auto Cal) at specified time intervals
ranging from minutes to months.
By performing measurements on either one calibration gas (offset or span) or on two calibration gases (zero and
span), the unit can correct for changes in the response of the transmitter without operator intervention.
At the specified time interval, the TMO2D activates a solenoid valve on a sampling system using one of the relays
provided. This procedure isolates the transmitter from the process stream and connects the transmitter to one of the
calibration gases. After a programmable time, during which the calibration gas replaces the process gas, the
transmitter takes measurements of the calibration gas.
The analyzer then activates a second solenoid valve, using a second relay, to connect the transmitter to the other
calibration gas. The transmitter then equilibrates as the second calibration gas replaces the first gas, and takes
measurements of the second calibration gas.
After taking span and zero gas measurements, the TMO2D reconnects the transmitter to the process stream. Then a
final settling time takes place while the process gas replaces the calibration gas.
Once settling has been completed, if no error has occurred, the analyzer calculates the amount of drift and applies
the calculated drift to the factory calibration data. The factory calibration data remains unchanged. The TMO2D
stores the corrections to the calibration data as the Drift Curve.
If the Auto Cal measurements are beyond the preprogrammed limit, the unit disregards the data and uses the drift
curve already stored in memory. If you have enabled Auto Cal Error Handling (see page 48), the display and outputs
will respond as programmed. If any alarm relays have been assigned to trip on Auto Calibration Errors, they will be
tripped. Contact the factory to expand the AutoCal drift limits. The default limits are 25% of full scale per calibration
and 40% of full scale total drift.
Alternately, the automatic calibration can be performed in an offset or span correction manner using a single
calibration gas and one solenoid valve. When calibration is active, the autocalibration status replaces the display of
pressure or background:
• Cal:ok (no errors and no new cal data applied)
• Cal:new (no errors and new data applied)
CALIBRATION MENU
Pressure Calib?
Press [YES] to enter the “Pressure Calibration?” submenu.
PRES XDUCER CURVE
ENTRY
# of Points [X]:
Use the numeric keys to enter the number of points, and press [YES] twice to
confirm the entry.
Point # 1
mmHg [XXX.X]:
Use the numeric keys to enter the pressure in mmHg for the given point, and press
[YES] twice to confirm the entry.
Point # 1
Pres mA [X.XX]:
Use the numeric keys to enter the corresponding mA value for the point, and press
[YES] twice.
CALIBRATION MENU
Pressure Calib?
Press [NO] to proceed to the Auto Cal submenu.