1.4 Analyzer Inputs and Outputs
1.4.1 The Oxygen Sensor Input
The oxygen sensor electrical input to the model 1100 is used to indicate the oxygen concentration
measured by the model MAX-250 oxygen sensor. It is proportional to the oxygen present in the
measured gas at the sensor membrane. The oxygen sensor input is a female 3-pin 180° DIN
connector designed to mate with the supplied sensor interface cable connector.
1.4.2 Alarm-1 Relay Output
The Alarm-1 relay is mapped to the Alarm-1 set point, and is provided for process control use. The
user may set the oxygen level at which Alarm-1 activates (section 3.2.2). Alarm-1 may be
configured as ascending (highest oxygen level allowable) or descending (lowest oxygen level
allowable) action. The relay output may be configured for fail-safe (relay coil de-energized in alarm
state) or non-fail-safe (relay coil energized in alarm state) action. Factory default settings are
ascending, and non-fail-safe (Appendix C, Factory Configuration). The Alarm-1 relay contacts are
Form C (DPDT), voltage-free.
1.4.3 Alarm-2 Relay Output
The Alarm-2 relay is mapped to the Alarm-2 set point, and is provided for process control use. The
user may set the oxygen level at which Alarm-2 activates (section 3.2.3). Alarm-2 may be
configured as ascending (highest oxygen level allowable) or descending (lowest oxygen level
allowable) action. The relay output may be configured for fail-safe (relay coil de-energized in alarm
state) or non-fail-safe (relay coil energized in alarm state) action. Factory default settings are
ascending, and non-fail-safe (Appendix C, Factory Configuration). The Alarm-2 relay contacts are
Form C (DPDT), voltage-free.
1.4.4 Fault Relay Output
The Fault relay output is used to indicate that there is at least one system fault active on the Model
1100 analyzer (section 4.3.1 – fault codes and definitions). The relay output action is fail-safe, and
it is not configurable. This means that the contact is closed provided there are no faults. The Fault
relay contacts are Form B (SPST), voltage-free.
1.4.5 Analog Voltage Output
The Analog Voltage output is a dynamic potential used to indicate to a remote device the displayed
oxygen concentration during normal analyzer operation and system maintenance. The Analog
voltage output follows the oxygen readout displayed on the 7-segment LED display during all
system and user modes except for user setup. For a complete listing of available output levels by
analyzer range, refer to Appendix E – range / output chart.
The Analog voltage range can be adjusted by the user (section 4.1 – system setup). Available
settings are 0-VDC for minimum-scale-deflection, to 1, 5 or 10-VDC full-scale. Please note that the
0-5 VDC output is limited to a maximum of 4.93. The factory default setting is 0-1 VDC (Appendix
C, Factory Configuration). The Analog voltage output is scaled according to the analyzer’s
selected range, and must be used in conjunction with the Range ID voltage when the analyzer is
configured for auto-ranging (section 1.4.8).
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