User Manual

Logical I/O blocks
Input blocks
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Status Flag [StaFlg]
The status flag [StaFlg] indicates the state of the I/O block. This pin consists of four Boolean values:
● IN_ALARM: Logic 1 (TRUE) if the event state pin [EvtSta] does not display NORMAL as its value.
● FAULT: Logic 1 (TRUE) if the [Rlb] pin does NOT display the value NO_FAULT_DETECTED.
● OVERRIDDEN: Logic 1 (TRUE) if the block point was overridden locally (e.g., manual switch on I/O
module). If this flag is set, [PrVal] and [Rlb] will no longer display any changes in the physical
input/output.
● OUT_OF_SERVICE: Logic 1 (TRUE) if the out-of-service pin [OoServ] is active.
Default Value [DefVal]
For an input block, [DefVal] is transmitted to [PrVal] when [OoServ] is set to TRUE.
For an output block, value [DefVal] is transmitted to [PrVal] when none of the priorities (1…16) is active.
19.2 Input blocks
An input block is used to enable an input signal (e.g., a measured value) in the program to be handled as a
process value.
Analog Input (AI)
The analog input is the logical image, or memory map, of an analog measured value and describes its
properties. The raw data is converted and made available in the form of a current value (Present Value) at
the block output for further processing within the program.
The following functions are integrated in the block:
● Conversion of the input signal with slope [Slpe] and intercept [Icpt].
● Interruption of input signal [OoServ] and replacement with [DefVal]
● Limit value monitoring (OFFNORMAL alarm)
● Reliability monitoring [Rlb] (FAULT alarm)
● Change of state messages (events / system events)
Processing and displaying the current value
The measured raw value is converted into the measured present value in accordance with a conversion
curve. This present value is available at [PrVal] for further processing within the program.
Slope/Intercept
The conversion curve is a linear function which takes the following form:
[PrVal] = Raw value * Slope + Intercept
The values for slope [Slpe] and intercept [Icpt] must be defined specifically for the application concerned
in accordance with the I/O system in use and the signal type.
For slope and intercept values for SBT products, see
Slope [Slpe] and Intercept [Icpt] . For sensors not
listed, the following applies:
Calculating [Slpe] and [Icpt]
The values for [Slpe] and [Icpt], which are to be entered in the block, must first be calculated. These values
are derived from the individual [Slpe] and [Icpt] values of the signal type and the signal transducer in
accordance with the following formula:
[Slpe] = (Slope
SignalType
/ Slope
SignalTransducer
)