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Siemens TX-I/O™ Module system – Functions and operation CM110561en_08
Building Technologies Indicators and operator controls 2018-10-25
2.6 Fault messages
Quality value
Signal type
put
of process value
CI Mech (10/25Hz), CI El (100Hz)
The function operates under normal conditions.
The function is not operating. The process value is not valid.
Reliable operation can't be guaranteed due to low DC 24 V operating voltage. This item will
only be sent if a switching operation has to be commanded.
Reliable operation can't be guaranteed due to missing / failed AC voltage. This item will be
modified immediately when the AC voltage fails. The output will be switched off/inactive.
Unreliable Other
BO Bistable
AC / DC24 V is not present. The “PowerDownModeAC24V” becomes active.
Remark: Ifparameter [PowerDown ModeAC24V] is set to “Keep”, the
“PowerDownModeAC24V” will not become active and the fault will not be set.
With modules from Series D, however, it is compulsory to feed AC 24 V to bus conductor
" V
" . The module always monitors this supply.
Simatic: It is also admissible to connect DC 24 V to bus conductor " V ".
AI Measure
– The voltage on G8 is below a certain level. The external device delivering the current may
be unreliable (for current measuring SignalTypes only).
– The voltage on AC / DC 24 V is below a certain level. The external device delivering the
voltage may be unreliable (for voltage measuring SignalTypes only).
Mapping error in multistate function.
The sensor connected to the input is reading a value higher than the normal operating range.
The sensor connected to the input is reading a value lower than the normal operating range.
The connection between the defined object and the physical device is providing a value
indicating a short circuit condition.
Open Loop The connection between the defined object and the physical device is providing a value
indicating an open circuit condition. Exception: Pt 4-wire, open circuit of a single conductor.
4...20 mA current measuring signal type measures no current.
part of process
The status and quality information are coded in the process value (raw data).