DM-634C Oxygen Sensor Assembly
DM-634C O2 Sensor Instruction Manual Rev. .066
Page 10 of 25
VDC Power In
4-20mA Output
RS-485 In
RS-485 Out
TO SENSOR
Place un-used alarm
programming
jumper tabs here
Alarm Dry Contacts
Fault ALM2 ALM1
Jumper Programmable Alarm Outputs
Normally Open or Normally Closed
Optional Voltage
Developing Resistor
Use 250ohm 1/4W
R1
Fault
ALM2
ALM1
Figure 8
Sensor Connector PCB
If a jumper tab is installed in the latch position, that alarm relay will be in the latching mode. The latching
mode will latch the alarm after alarm conditions have cleared until the alarm reset function is activated. The
non-latching mode (jumper removed) will allow alarms to de-activate automatically once alarm conditions
have cleared. If a jumper tab is installed in the energize position, that alarm relay will be in the energized
mode. The energized mode will energize or activate the alarm relay when there is no alarm condition and de-
energize or de-activate the alarm relay when there is an alarm condition. The de-energized mode (jumper
removed) will energize or activate the alarm relay during an alarm condition and de-energize or de-activate the
alarm relay when there is no alarm condition.
If a jumper tab is installed in the ascending position, that alarm relay will be in the ascending mode. The
ascending mode will cause an alarm to fire when the gas concentration detected is greater than or equal to the
alarm set point. The descending mode (jumper removed) will cause an alarm to fire when the gas concentration
detected is lesser than or equal to the alarm set point. Except in special applications, O2 gas monitoring will
require alarms to fire in
“DESCENDING”
gas conditions.
Any unused jumper tabs should be stored on the connector board on the terminal strip labeled “Unused
Jumpers” (see Figure 8).