Detcon DM-634 - Manual (Page 16)

“SET ALARM 1 LEVEL”. Enter the menu by holding the programming magnet stationary over “PGM 1”
for 3 seconds until the display reads
“SET ALM1 @ 19.5%”, then withdraw the magnet. Use the program-
ming magnet to make an adjustment to “PGM 1” to increase or “PGM 2” to decrease the display reading until
the reading is equal to the desired alarm set point. Exit to the programming menu by holding the programming
magnet over “PGM1” for 3 seconds, or automatically return to the programming menu in 30 seconds.
c) ALARM 2 LEVEL From the programming menu scroll to the alarm 2 level listing. The menu item appears as:
“SET ALARM 2 LEVEL”. Enter the menu by holding the programming magnet stationary over “PGM 1”
for 3 seconds until the display reads
“SET ALM2 @ 17.5%”, then withdraw the magnet. Use the program-
ming magnet to make an adjustment to “PGM 1” to increase or “PGM 2” to decrease the display reading until
the reading is equal to the desired alarm set point. Exit to the programming menu by holding the programming
magnet over “PGM1” for 3 seconds, or automatically return to the programming menu in 30 seconds.
d) Exit back to normal operations by holding the programming magnet over “PGM 2” for 3 seconds, or automati-
cally return to normal operation in 30 seconds.
3.9.2 Alarm Reset
An alarm condition will cause the applicable alarm to activate its corresponding relay and LED. If alarm 1, alarm 2,
or fault alarms have been programmed for latching relays, an alarm reset function must be activated to reset the
alarms after an alarm condition has cleared. To reset the alarms, simply wave the programming magnet over either
“PGM 1” or “PGM 2”, momentarily, while in normal operations mode and note that the corresponding alarm
LED(s) turn off.
3.9.3 Other Alarm Functions
Alarms are factory programmed to be non-latching, de-energized; and to f ire under ascending gas conditions. The
fault alarm relay is programmed as normally energized which is useful for detecting a 24VDC power source failure.
All alarm functions are programmable via jumper tabs. Changing alarm functions requires the sensor housing to be
opened, thus declassif ication of the area is required. See section 3.5.4-e for details.
3.10 P
ROGRAM
F
EATURES
Detcon MicroSafe™ toxic gas sensors incorporate a comprehensive program to accommodate easy operator inter-
face and fail-safe operation. Program features are detailed in this section. Each sensor is factory tested, programmed,
and calibrated prior to shipment.
Over Range
When the sensor detects gas greater than 25.0% O2, it will cause the display to f lash “25.0 % O2” on and off.
Sensor Fault
If either of the wires connecting the sensor cell to the connector board should fail and cause an open circuit, the
sensor will go into a fault condition. “SENSOR FAULT”.
Calibration Fault
If during calibration the sensor circuitry is unable to attain the proper adjustment for span, the sensor will enter into
the calibration fault mode and cause the display to alternate between the sensor’s current status reading and the cali-
bration fault screen which appears as: “CAL FAULT”.
Fail-Safe/Fault Supervision
Detcon MicroSafe™ sensors are programmed for fail-safe operation. Any fault condition will activate the fault relay,
illuminate the fault LED, and cause the display to read its corresponding fault condition: “SENSOR FAULT”, or
“CAL FAULT”. A “SENSOR FAULT” will also cause the mA output to drop to zero (0) mA.
Sensor Life
The sensor life feature is a reference based on signal output from the sensor cell. When a sensor life of 25% or less
remains, the sensor cell should be replaced within a reasonable maintenance schedule.
3.11 RS-485 P ROTOCOL
Model TP-624C MicroSafe™ sensors feature Modbus™ compatible communications protocol and are addressable
via rotary dip switches for multi-point communications. Other protocols are available. Contact the Detcon factory
for specific protocol requirements. Communication is two wire, half duplex 485, 9600 baud, 8 data bits, 1 stop bit,
Detcon Model DM-634 Oxygen Sensor PG.16