Additional Information On Sm 331; Ai 2 X 12 Bit - Siemens SIMATIC Manual

6.8.4

Additional information on SM 331; AI 2 x 12 Bit

Unused channels
Short-circuit unused channels and connect these with M
immunity of the analog input module. Set the "disabled" value at the "measurement type"
parameter for unused channels. This setting reduces module cycle times.
Also short-circuit the COMP input if this is not used.
As certain programmed inputs may remain unused due to the channel group configuration,
make allowances for the special features of these inputs outlined below in order to be able to
use the diagnostics functions at these used channels:
● Measuring range 1 V to 5 V: wire the used input and unused input of the same channel
group in parallel.
● Current measurement, 2-wire transducer: There are two options of setting up the channel
circuit:
a) Open unused input; channel group diagnostics disabled. The analog module would
trigger a single diagnostics interrupt and set its SF LED if diagnostics is enabled.
b) Terminating the unused input using a 1.5 kΩ to 3.3 kΩ resistor. This allows you to
enable diagnostics for this channel group.
● Current measurement 4 mA to 20 mA, 4-wire transducer: wire the used input and unused
input of the same channel group in series.
Line continuity check
The line continuity check is designed only for temperature measurements (thermocouples
and thermoresistors.)
Special features of the line continuity check for the 4 mA to 20 mA measuring range
If you configured a measuring range of 4 mA to 20 mA, and enabled the line continuity
check, the analog input module logs a wire-break event to diagnostics data when the current
drops below 3.6 mA.
The module also triggers a diagnostics interrupt if this function is enabled in the program.
A wire break can only be signaled by means of the lit SF LED and the diagnostic bytes must
be evaluated in the user program if diagnostics interrupts are disabled.
If you configured a measuring range of 4 mA to 20 mA, disabled the line continuity check
and enabled diagnostic interrupts, the module triggers a diagnostic interrupt when the
underflow value is reached.
S7-300 Module data
Manual, 06/2017, A5E00105505-AJ
6.8 Analog input module SM 331; AI 2 x 12 Bit; (6ES7331-7KB02-0AB0)
Analog modules
. This optimizes interference
ANA
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