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)

[Icpt] = (Intercept SignalTransducer / Slope SignalTransducer ) + Intercept SignalType

[Slpe] is calculated on the basis of:

[Slp] = (InterpolationPoint_y2 – InterpolationPoint_y1) / (InterpolationPoint_x2 – InterpolationPoint_x1)

Binary Input (BI)

The binary input block is the logical image, or memory map, of a binary switch value and describes its properties. The parameters of the physical value are set via the polarity [Pol], and the value is then available as the present value for further processing. The Present Value is monitored for a given state. For commissioning and test purposes, or in the event of an error, the Present Value can be dissociated from the process and overwritten with a replacement value.

The following functions are integrated in the block:

  • Inversion of the input value
  • Interruption of input signal [OoServ] and replacement with [DefVal]
  • Alarm value monitoring (OFFNORMAL alarm)
  • Reliability monitoring [Rlb] (FAULT alarm)
  • Change of state messages (events / system events)
  • Runtime totalization and maintenance messages

Multistate Input (MI)

The multistate input block is the logical image, or memory map, of several binary switch values or a direct hardware multistate value, and describes its properties. The multistate capability is achieved by interconnecting a number of individual binary states. The binary states are evaluated and mapped as integers. Each integer in the series is allocated a text label which is further processed and interconnected within the program as a current value. For commissioning and test purposes, or in the event of an error, the Present Value can be dissociated from the process and overwritten with a replacement value. As an auxiliary function, the runtime total for this multistate input can be registered and evaluated.

The following functions are integrated in the block:

  • Interruption of input signal [OoServ] and replacement with [DefVal]
  • Alarm value monitoring (OFFNORMAL alarm)
  • Reliability monitoring [Rlb] (FAULT alarm)
  • Change of state messages (events / system events)
  • Runtime totalization and maintenance messages
  • Hardware mapping

Pulse converter (pulse counter)

The pulse converter object cumulates pulses for a meter. The Pulse converter object is used where meter values already manipulate in a meter object or where changes of values are required to further process control programs. Applications include: Establishing 24-hour/7-day/monthly meters, transmission by the minute of meter values to peak load programs, etc. Precision and round off error based on real arithmetic is possible.

Specific properties

The counter value is scaled as a REAL number directly in the object using the scaling factor. COV forming the Present_Value can be value or time-related and a timestamp with the logged time is always provided with the Present_Value. Reduction of Present_Value by a value (subtraction) is supported as a standard. You can set it to a pre-defined value using a trigger function (proprietary expansion).

The Pulse Converter object can be used in two different manners: Counting or metering. The type of application is parameterized using the FnctMod parameter.

The referenced object, e.g., an external device provides the pulse value:

  • Present_Value for the pulse converter object represent the pulse count of the referenced object: The difference to the last read value is added for each record.
  • Present_Value can be set via the system.
  • After start-up, the pulse converter object encompasses the last stored counter value:
  • After a change in counter, the pulse converter object encompasses a false counter value.
  • Typical application: On-board I/O with pulse logging.

The referenced object, e.g., an external device provides the absolute pulse value:

  • Present_Value from the pulse converter object represents the absolute counter value of the referenced object.
  • Under no circumstance may the Present_Value be set via the system.
  • After start-up or a change in counter, the pulse converter object after includes the correct counter value.
  • Typical applications:
    • Access to an accumulator or pulse converter object is another BACnet device
    • I/O Open module or M-bus with counter value integration
    • Integration of a device via LON
  • Incorrect applications: I/O module with pulse recording

Accumulator object (counter value)

The accumulator object can map counter states unchanged and free of errors due to rounding off or add the counter pulse without loss and scale the same. The accumulator object is suitable to displaying meter values that justify monetary performance. For this type of counter values, manipulations such as monthly values, etc., must never be made directly in the meter object.

The addition of counter pulses and scaling without loss is accomplished using whole-number operations with residual value processing. The conversion of physical pulses can be adapted using a presale parameter. The resulting Present_Value is a scalable variable.

Present_Value depends on the function mode to synchronized adjustable to any value using a physical meter with the last value prior to setting saved with a date/time stamp.