ATI Series D12 Toxic Gas Transmitter with H10 Smart Sensor
Revision N (7/15) 32
Main Reading
The main reading represents the gas concentration value and appears on the Main Display, along with
the gas name, and units of concentration. It is reported on the 4-20mA output
1
, and is the PV (Primary
Variable) reported on the optional HART™ interface. It also appears at
register 40043 (D12_SYS_CONCBL) on the optional Modbus interface.
By default, the main reading is blanked to suppress the display of negative
values. That is, the reading is reported as zero if the concentration should dip
below zero, which can occur over time as a result of sensor aging. If the
concentration falls to –20% of the full-scale range, a fault alarm is generated. Blanking is typically
extended slightly above zero, as a means of stabilizing the main reading in the presence of excessive
external noise, or other environmental factors (see Sensor Setup Page).
During zero and span calibration, the “un-blanked” gas concentration value is displayed, primarily to
assess the amount of positive or negative drift. The “un-blanked” reading is also available on the
Modbus interface (request “D12 Transmitter Modbus Interface Manual”, for more information).
1
The 4-20mA may not match the reading when the “L” status indicator is visible on the Main Display, or when the output is in
a physical limit.
PPM
H2S
Main Display
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