Analog Modules
4-162
Programmable Logic Controllers S7-300 Module Data
A5E00105505-03
Default Settings
The default settings of the module in STEP 7 are the “voltage” measuring method
and the “" 10 V” measuring range. You can use this combination of measuring
method and measuring range without parameterizing the SM 331; AI 8 12 bits
with STEP 7.
Wire-Break Check
The wire-break check is intended primarily for temperature measurements
(thermocouples and bulb resistors.
Special characteristics of the wire-break check for the 4 to 20 mA measuring
range
With a parameterized measuring range of 4 to 20 mA and enabled wire-break
check, the analog input module enters wire-break in the diagnosis when a current
falls below 3.6 mA.
If you have enabled diagnostics interrupt during configuration, the module
additionally triggers a diagnostic interrupt.
If no diagnostic interrupt has been enabled, the illuminated SF LED is the only
indication of the wire-break and you must evaluate the diagnostic bytes in the user
program.
With a parameterized measuring range of 4 to 20 mA and disabled wire-break
check and enabled diagnostic interrupt, the module triggers a diagnostic interrupt
when the underflow is reached.
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