Siemens Simatic RTU303xC Series Operating Instructions Manual page 254

Program blocks
5.3 Often used parameters
"Retentivity" function parameter
Retentivity means that block values such as counter values and statistics data are saved in
RAM for up to 3 hours when the RTU is shut down. The values are still present after a restart
and block processing continues with the existing values. The values are retained even in the
event of a change to the configuration, if the signals or parameters remain unchanged in the
individual block types.
The option can be activated across block types for up to 32 blocks. This includes the
following block types:
● Counter
● Uptime counter
● Flow totalizer
● Flow calculation rectangular weir
● Statistics
Output parameter "Error"
The output parameter "Error" is set in the following situations:
● In an analog value block, the value is outside the range of values.
This occurs when the value calculated by the block is outside the permitted range of
values of the tag type of the output.
● A message generated by a block cannot be saved because the maximum number of
messages to be saved has been reached (transfer buffer full).
When the output parameter "Error" is set, other output parameters are not updated but retain
the last values before the error occurred.
Recurring settings of parameters
With most program blocks there are default settings of the input and output parameters that
are explained here.
Settings of input parameters
Many blocks have recurring parameters which will be described in advance here. The
settings described below mainly involve parameters for digital tags (except "En").
- empty (no entry) -
●
Default for required inputs of a block
If the input is not configured, the configuration cannot be adopted.
● Unused
Default for optional parameters of a newly created block
Inputs with the setting "Unused" are not evaluated.
If all inputs of a block use this setting, the block will not be processed (e.g. "Logical OR").
254
Operating Instructions, 06/2019, C79000-G8976-C382-06
RTU303xC