ATI Series D12 Toxic Gas Transmitter with H10 Smart Sensor
Revision N (7/15) 59
4-20mA Output
The 4-20mA output normally sources
positive current to a receiver, proportional to
the main reading. The output is 4 mA at zero,
and rises to 20mA at the full-scale range (see
“Range” variable in Sensor Setup Page), and
may go as high as 24mA (125% Range) in
case of gas flooding. Since the reading is
blanked below zero, the output should never
go below 4mA in the course of normal
operation.
Figure 56. Current loop output plot
Output Overrides
By default, the output is forced to 3.6mA to signal fault alarms to the receiver. During alarm inhibit
and auto-test modes, the loop is fixed at 4.0mA (17.4mA for Oxygen sensors) to prevent false alarms at
the receiver. These are the default values, which may be changed on the 4-20mA Setup page shown in
Figure 57.
4-20mA Setup
Variables listed on this page are described in
Figure 57. 4-20mA setup page
Table 12. 4-20mA variables
Autotst_mA
The Autotst_mA variable is the mA value output during Auto-test mode – to prevent
false alarms at the receiver. The default is 4.0mA (17.4mA for Oxygen sensors), and
is limited between 3.5
9
and 22.0 mA.
Inhibit_mA
The Inhibit_mA variable is the mA value output during the Alarm Inhibit mode – to
prevent false alarms at the receiver. The default is 4.0mA (17.4mA for Oxygen
sensors), and is limited between 3.5
2
and 22.0 mA.
Fault_mA
The Fault_mA variable is the mA value output during Fault alarms. The default is
3.6mA, and is limited between 3.5mA
2
and 22.0mA. The value should be recognized
as a fault by the loop receiver.
More
More is a link to the 4-20mA control page.
9
Since the transmitter may be powered from the current loop, 3.5mA is the lower limit for all settings.
►Autotst_mA= 4.0
Inhibit_mA= 4.0
Fault_mA= 3.6
More
>Menu >Setup >4-20mA
0
4
8
12
16
20
24
0 20 40 60 80 100
mA
%Range
4-20mA Output
Fault = 3.6mA
Autotst_mA= 4.0
Inhibit_mA = 4.0
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