Teledyne 9060 Operating Instructions Manual page 24

2.11 AUTO PURGE
In oil and coal fired plants, it is possible for the probe sensing filter to become
blocked. An automatic purge cycle can be set up so that a blast of air, maximum 100 kPa
(14.5 psi), will automatically back-flush the probe filter on a timed basis. Refer to Set-up
steps 52 to 56 in Section 5.5. A purge pressure switch will sense if there is insufficient
flow to clear the filter during the purge cycle. In this case a 'PROBE FILTER' alarm will
occur. The probe can be manually purged from the keyboard while in 'RUN' mode. The
transmitter output is not frozen during or after the pressing of this button.
If two probes are being used, the two probes could be driven by a common
solenoid but separate pressure regulators and pressure switches (See section 3.11)
2.12 RS 485 NETWORK (MODBUS™) AND RS 232C PORT
The serial port has two functions. -
It can be configured to connect up to 31 transmitters together on a MODBUS™ RS485
network. Each individual transmitter can be interrogated by a computer or PLC. The
values of oxygen, sensor EMF, sensor temperature, sensor impedance for both oxygen
sensors (if two sensors are being used on one transmitter) can be read over the
network. The alarms status can also be checked over the network. For the connection
details, see Section 3.15 and Appendix 6.
It can be used to log the transmitter readings by connecting the transmitter to a printer,
a data logger, or any computer using an RS232-C com port.
When it is to be used to log the transmitter readings, use set-up step 82 to selected the
items to be sent to the data logger. The log period may be selected in set-up step 83,
and the baud rate may be set in set-up step 84. Alarms, including the time they
occurred, will be transmitted to the printer and computer whenever they are first
initiated, accepted and cleared. The protocol for the serial port is eight data bits, one
stop bit, no parity.
2.13 AUXILIARY TEMPERATURE THERMOCOUPLE
A flue thermocouple must be connected to the AUX thermocouple input when
combustibles display is required.
The AUX thermocouple may also be used to monitor and display any process
temperature.
2.14 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 reset
up to three times until normal operation is resumed. Reset cycles are displayed by the
POWER light on the keyboard. A steady 'ON' light indicates normal operation. If the
program has not resumed normal operation after three attempts to reset, the common
alarm relay will be activated. The reset function will continue repeatedly after the alarm. If
a successful reset is achieved, the alarm will be cancelled and the transmitter will continue
to run normally.
9060-Zirconia Analyser