User guide

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MRK-D-0022 V3.1 Aeroqual Series 200, 300 & 500 User Guide
5.2. Wiring for Control
The control pin can be wired to supply control of a gas concentration between upper and lower
concentration limits. The upper and lower limits can be set by the user. The factory default settings
are dependent on the gas sensor head selected at time of purchase.
To switch to GND use pins 3 and 6. For a 12V output wire to pins 3 and 1 (see following diagram for
typical wiring). This feature will only operate while powered by the AC adaptor.
Control is achieved by using a software latch. If power is lost to the monitor, the switch will open and
therefore turn off the external device connected to the monitor external output. The following wiring
diagram demonstrates the typical wiring to achieve the required control.
Note: Failure to insert a circuit protection diode, shown as above, will result in damage to the
monitor if a voltage spike is created by the relay.
5.3. Wiring the 0-5 V Analogue Output
The 0 to 5 V signal is a proportional signal based on the measurement of the selected output sensor.
The voltage out spans the specified gas sensor concentration range. For example: With the low
concentration ozone sensor head: 0 V represents 0 ppm ozone and 5 V represents 0.500 ppm ozone.
Note: The ultra-low ozone sensor is a special case – 1.5V represents 0.150ppm ozone in this
case.
Note: Wire between pins 2 & 6
See Section 7.1 for output status conditions.