Analog Input (Bytes 8 To 11); Parameterization Error (Bytes 8 To 11, Bit 0); Common Mode Error (Bytes 8 To 11, Bit 1); Wire-Break (Bytes 8 To 11, Bit 4) - Siemens SIMATIC S7-300 Manual

Data exchange with SM 335
3.4 Evaluating the diagnostics data of SM 335

Analog input (bytes 8 to 11)

SM 335 sets the bits in the channel specific diagnostics bytes of the inputs after it has
detected a fault at one of the inputs. The channel-specific diagnostics bytes of the inputs are
assigned as follows:
Figure 3-15
Note
Common mode errors are output as ground fault in the diagnostics view of HW Config.

Parameterization error (bytes 8 to 11, bit 0)

This set bit indicates a parameterization error.

Common mode error (bytes 8 to 11, bit 1)

The common mode voltage at the analog input exceeds the limit. If the common mode
voltage is too high, SM 335 simultaneously sets bit 2 in module diagnostics byte 1 and the
measured value to 7FFF
SM 335 resets the bit after the common mode voltage has recovered a valid value. (refer to
chapter Wiring the analog inputs (Page 26): Wiring the analog inputs)

Wire-break (bytes 8 to 11, bit 4)

Bit 4 In the channel-specific diagnostics byte of the analog input is set after a wire-break has
been detected at the analog input.
Underflow, overflow (bytes 8 to 11, bit 6 + 7)
The measured value at the input is checked for overflow (bit 7) and underflow (bit 6). The
corresponding bit is set if the analog value is in overflow or underflow state.
66
Channel-specific diagnostics byte for analog input
.
H
SM 335 - High-speed analog mixed module for SIMATIC S7-300
Manual, 02/2009, A5E02409063-01