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Module T8433
Issue 11 Apr 10 PD-T8433 20
3.2.3. Rack 3: AI
The AI board returns the field loop current at the input.
Channel Description
1 Field input channel 1 current
2 Field input channel 2 current
20 Field input channel 20 current
21 Field input channel 1 redundant current
40 Field input channel 20 redundant current
Table 8 Rack 3: AI descriptions
The current is the median value taken from the triplicated module. The current level is reported as an
integer, scaled in 12 bit equivalent "presentation units" as shown in the table below. This may be used
directly, scaled arithmetically to 0-20mA or scaled using the IEC1131 TOOLSET conversion tables.
Presentation Units Current (mA)
-2048 Open Circuit
-1024 0 mA
0 4 mA
4096 20 mA
Table 9 Rack 3: Presentation Units