Analog modules
9.2 SM 336; AI 6 x 13 Bit
Fail-safe signal modules
Installation and Operating Manual, 01/2010, A5E00085586-10
215
Discrepancy analysis for fail-safe analog input modules
If you have configured safety mode in accordance with SIL 3, you can configure a
discrepancy time and an absolute tolerance window (as a % of the 4 mA to 20 mA
measuring range) for each input of the analog input module. In addition, configure the
standard value (MIN = lower value / MAX = higher value) to be applied and transferred to the
F-CPU.
If the difference between the two measured values is outside of the tolerance window for
longer than the configured discrepancy time, this error is signaled and the fail-safe value
(7FFF
H
) is transferred. In
S7 Distributed Safety
, the fail-safe value 0 is provided in the PII for
the safety program in place of 7FFF
H
.
9.2.10 Diagnostic Messages for SM 336; AI 6 x 13 Bit
Possible diagnostic messages
The following table provides an overview of the diagnostic messages for
SM 336; AI 6 x 13Bit.
Diagnostic messages are assigned either to a channel or to the entire module. Some
diagnostic messages occur only in certain applications.
Table 9- 11 Diagnostic messages of SM 336; AI 6 x 13Bit
Diagnostic message Signaled in the
application
Effective
range of
diagnostics
Assignabl
e
Wire break 1, 2, 3, 4, 5, 6
Discrepancy error 4, 6
A, B Channel Yes
Common mode fault 1, 2, 3, 4, 5, 6 A, B, C
Overflow or underflow of the measured
value (see "Wire break and underflow") in
Chapter " Analog value representation
(Page 182) ")
1, 2, 3, 4, 5, 6 A, B, C
Channel
Incorrect module parameters
Parameter assignment error (with
specification of consecutive number)
ADC/DAC error
No external auxiliary voltage
Communications error (CPU in Stop)
Time monitoring activated (watchdog)
EPROM / RAM fault
Processor failure
1, 2, 3, 4, 5, 6
A, B, C
CRC signature error
Timeout of safety message frame
monitoring
3, 4, 5, 6
Message frame error 1, 2
A, B, C
module
No
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