The zero calibration takes longer than the span calibration. The maximum time involved with a zero calibration is
around 50 seconds, and for a span calibration the time is around 30 seconds.
If a calibration has been unsuccessful due to an interrupted gas flow, contaminated calibration gas, or excessive
temperature (ie: >50°C {>120°F} ), re-initiate the calibration from the 9070 keyboard.
Do not under any circumstances tamper with or open the CO
2
analysis chamber. Doing so will void the manufacturers
warranty. There are no user servicable parts inside, and any tampering will drastically reduce it’s performance and
lifetime. Any Analysis chamber sent back for repair which has been tampered with will have to be replaced.
If the carbon dioxide module fails, it should be sent back to the manufacturer for repair, and factory re-calibration.
In addition, there is an automatic process that uses the oxygen signal to enable an offset for the CO
2
cell to be read and
saved. This system ensures that the CO
2
cell will always read zero when air is flowing in the cell.
2.11 RS 485 AND RS 232C PORT
The serial port is for connecting a printer, a data logger, or any computer with an RS 485/ 232-C port. It can be used to
monitor the transmitter and process by logging the values of functions selected in step 53 of the set-up menu in Section
5.5.
The log period may be selected in step 20 for 1 to 2000 minutes for the printer mode or 5 to 1200 seconds for the data
log mode. The baud rate may be set up in step 51.
The protocol for the serial port is eight data bits, one stop bit, no parity.
Alarms, including the time they occurred, will be transmitted to the printer and computer whenever they are first
initiated, accepted and cleared (in the printer mode only).
If ‘Fast Sample or 'Display Sample' is selected in set-up step 26, each time a new minimum rate of oxygen is detected,
this value plus date/time, will also be printed (in the printer mode only).
NOTE: The RS232 port is not available in the model 9070-5 (With carbon dioxide installed).
2.12 AMBIENT TEMPERATURE AND RELATIVE HUMIDITY MEASUREMENTS
Ambient temperature and relative humidity are measured within the Analyzer to improve the accuracy of the oxygen
readings. These reading can be displayed on the lower line of the LCD (see set-up step 29), or may be logged to the
printer/computer port ( see set-up step 53).
2.13 WATCHDOG TIMER
The watchdog timer is started if the microprocessor fails to pulse it within any one second period, (ie. fails to run its
normal program).
The microprocessor will then be repeatedly reset until normal operation is resumed. Reset cycles are displayed by the
‘POWER’ light above the keyboard on the front panel. A steady ‘ON’ light indicates normal operation. If the program
has not resumed normal operation after two attempts to reset, the common alarm relay will be activated. If a successful
reset is achieved, the alarm will be cancelled and the Analyzer will continue to run normally.
2.14 BACK-UP BATTERY
The transmitter’s RAM and real-time clock are backed up by a lithium battery in the event of power failure. All set-up
variables are saved and the clock is kept running for approximately ten years with the power off. The battery module
should be replaced every 8 years. (It is the battery shaped device clipped in a socket labelled M1)
Page 14 Teledyne Analytical Instruments 9070 Oxygen Analyzer
