Wire Break; Underflow - Siemens Simatic SM331 Getting Started

8.3.4

Wire break

Meaning
If wire break detection is enabled for 2-wire transducers, there will be no direct check for a
wire break. The diagnostics instead reacts on the shortfall of the low limit current value.
With 4 to 20 mA current transducer, the diagnostic message "Analog input wire break" is
shown in the module diagnostics when the current goes below 3.6 mA.
Figure 8-4
The display of the analog values shows an underflow (Hex 8000) immediately even if the
current measured is clearly above 1.1185 mA.
Underloading 3.6 mA is only possible if wire break detection has been disabled.
8.3.5

Underflow

Meaning
The display of the analog values shows an underflow immediately even if the current
measured is clearly above 1.1185 mA.
SM331; AI 8x12 Bit Getting Started part 1: 4 -20mA
Getting Started, 11/2006, A5E00253410-02
Left: Diagnostic message with wire break / Right: Variable table
8.3 Channel dependent diagnostic interrupts
Diagnostic interrupt
8-5