Siemens SIMATIC S7 F Manual page 207

Fail-Safe Blocks
Normal Value
The non-linearized value is adapted to its physical size using the input parameters
VLRANGE and VHRANGE and the measurement range and measurement type
(MODE) set in HWCONFIG. To enable the settings for VLRANGE and VHRANGE
to be switched to other block parameters, these are written to the outputs
OVLRANGE and OVHRANGE.
The conversion algorithm assumes a linear input signal.
When VLRANGE = 0.0 and VHRANGE = 100.0, you receive a percentage value.
When VHRANGE = VLRANGE is set, you receive the input signal of the analog
input module (e.g. mA) in accordance with the MODE setting.
16#80 is output as the quality code (QUALITY).
Measurement Range Coding of the Analog Input Module
The block is only released for the analog input module SM 336; AI 6 ✕ 13Bit; with
diagnostic interrupt. Only a measurement range of 4 to 20 mA is supported with a
measurement type of 2- or 4-wire measuring transducer. The coding of the
measurement range of the analog input module is carried out in HWCONFIG and
is applied at compilation automatically to the parameter MODE_xx of the
associated F module driver (F_M_AIx). F_CH_AI reads the value from the
associated F module driver. MODE can take on the following values:
Measurement Type
4-wire measuring
transducer
2-wire measuring
transducer
Simulation Value
A simulation value can be output at the output V instead of the normal value.
When the input parameter SIM_ON = 1, the value of the input parameter SIM_V is
output with the quality code (QUALITY) 16#60 and the output QSIM = 1 is set.
The output of the simulation value has the highest priority.
If a simulation value is selected that would result from a non-linearized value below
the rated range of the module, the output parameter QCHF_LL = 1 is set. If a
corresponding non-linearized value would exceed the rated range, the output
parameter QCHF_HL = 1 is set. In the event of overflow or underflow or violation of
the active limits, the output QBAD = 1 is also set, and then, depending on the
parameter assignment for the input SUBS_ON, a substitute value or the last valid
value is output.
Fail-Safe Systems
A5E00085588-03
Measurement MODE (Decimal/Hex.)
Range
4 to 20 mA 515 / 16#0203
4 to 20 mA 771 / 16#0303
8-19