Guide to function blocks

Diagnostic (DIAG)

Provides a method to monitor device alerts from non-fieldbus assets. Wire parameters or block outputs that indicate device health for non-fieldbus blocks to the Diagnostic block. These alerts from these diagnostic blocks are monitored by Inspect.

Fuzzy Logic Control (FLC)

Provides all the logic to perform standard PID control with the added benefit of superior response for both set point changes and external load disturbances.

Inspect

A block that receives statistics data so that you can view, plot, and add to historical data, the performance values in the system.

Lab Entry (LE)

Provides for operator input of offline lab analysis results.

Model Predictive Control (MPC)

Allows interactive processes to be controlled within measurable operating constraints while automatically accounting for process interaction and measurable disturbances.

Model Predictive Control Professional (MPCPro)

Allows large interactive processes (as large as 20×20) to be controlled within measurable operating constraints while accounting for process interaction and measurable disturbances. An embedded optimizer is included with the MPCPro block that can be used to effectively provide maximum profit or lowest cost production with the process constraints and limits on process inputs.

MPC Process Simulator

Simulates the actual process for use with the MPC function block for operator training.

Neural Network (NN)

Uses a neural network to predict a process output based on measured process inputs.

Analog Voter (AVTR)

Monitors a number of input values and determines if there are enough votes to trip. If a configured number of the inputs vote to trip, the block trips and sets the output of the block to 0 (zero).

Cause & Effect Matrix (CEM)

Defines interlock and permissive logic that associates as many as 16 inputs and 16 outputs. Configure one or more inputs to trip each output. When an input becomes active, all outputs associated with that input trip.

Discrete Voter (DVTR)

Monitors a number of input values and determines if there are enough votes to trip. If a configured number of the inputs vote to trip, the block trips and sets the output of the block to 0 (zero).

State Transition Diagram (STD)

Implements a user-defined state machine. The state machine describes the possible states, and the transitions between those states, that can occur.

Step Sequencer (SEQ) 

Associates system states with actions to drive outputs based on the current state.

Analog Tracking (AT)

Generates a discrete output that can be used to initiate the external tracking of the PID function block and to generate an analog output that can be used as the tracking input value of the PID function block.

Bias/Gain (BG)

Provides adjustable gain capability by computing an output value from a bias setpoint, an input, and a gain value The block supports output tracking.

Calculation/Logic (CALC)

Allows you to specify an expression that determines the block's output. Mathematical functions, logical operators, constants, parameter references, and I/O reference values can be used in the expression.

Control Selector (CTLSL)

Selects one of three control signals to perform override control to a PID function block. The block supports mode control.

Deadtime (DT)

Introduces a pure time delay in the value and status used in a signal path between two function blocks. The block supports signal status propagation and mode control.

Enhanced Control Selector (ECTLSL)

Selects one of sixteen control signals to perform override control to a PID function block. The block supports mode control.

Enhanced Ramp (ERAMP)

Ramps specified parameters in a target function block up or down to an endpoint at a specified rate or over a specified amount of amount of time.

Fieldbus Input Selector Extended (ISELX)

A mathematical and logical input calculation block that chooses an output based on up to 8 inputs.

Filter (FLTR)

Applies an equation to filter changes in the input signal and generates a smooth output signal. The block supports signal status propagation.

Input Selector (ISEL)

A mathematical and logical input calculation block that chooses an output based on up to 4 inputs.

Lead/Lag (LL)

Provides dynamic compensation for an input value. The block can apply a lead time function, a lag time function, or a combination of the two. A specified gain is applied to the compensated value, and the value is high/low-limited based on the block mode. The block supports mode control and signal status propagation.

Limit (LIM)

Limits an input value between two reference values. The block supports signal status propagation.

Manual Loader (MANLD)

Allows the block output to be set by an operator. The block supports output tracking and alarm detection.

PID (PID)

Combines all the necessary logic to perform analog input channel processing, proportional-integral-derivative (PID) control, and analog output channel processing within one function block. The block supports mode control, signal scaling and limiting, feedforward control, override tracking, alarm limit detection, and signal status propagation.

Ramp (RAMP)

Creates a ramping output signal to increase or decrease a variable toward a specified target value at a defined rate. The block supports signal status propagation.

Rate Limit (RTLM)

Limits the rate of change of the output value to specified limits. The block supports signal status propagation.

Ratio (RTO)

Applies an adjustable ratio setpoint to achieve a desired input/output relationship. The block supports signal filtering, mode control, output tracking, and alarm detection.

Scaler (SCLR)

Provides scaling and dimensional consistency between two values of different engineering units. The block converts the input value to the specified scale and generates an output value. The block supports signal status propagation.

Signal Characterizer (SGCR)

Characterizes or approximates any function that defines an input/output relationship. The block interpolates an output value for a given input value using the curve defined by the configured coordinates. Two separate analog input signals can be processed simultaneously to give two corresponding separate output values using the same defined curve. The block supports signal status propagation.

Signal Generator (SGGN)

Produces an output signal used to simulate a process signal. The block uses a specified combination of a sine wave, a square wave, a bias value, and a random value to generate the output signal.

Signal Selector (SGSL)

Selects the maximum, minimum, or average of as many as sixteen input values and places it at the output. The block supports signal status propagation.

Splitter (SPLTR)

Takes a single input and calculates two outputs based on specified coordinate values. The block supports mode control and signal status propagation.

Flow Metering (AGA_SI and AGA_US)

Implements the American Gas Association flow calculation standards for natural gases, namely AGA-3 (American Gas Association, Report No.3), AGA-7, and AGA-8.

Isentropic Expansion (ISE)

Calculates the final enthalpy for isentropic expansion of steam to a given pressure for a given entropy.

Steam Density Ratio (SDR)

Calculates the square root of the ratio of steam density to the density of steam corresponding to a flow meter calibration pressure and temperature.

Saturated Steam Properties at Temperature (SST)

Calculates steam enthalpy, entropy, specific volume, and pressure for saturation conditions specified by a given temperature.

Steam Properties (STM)

Calculates steam enthalpy, entropy, and specific volume for a given gauge pressure.

Saturated Temperature (TSS)

Calculates the steam temperature at saturation given the steam pressure.

Water Enthalpy (WTH)

Calculates the enthalpy of water for a specific temperature.

Water Entropy (WTS)

Calculates the entropy of water for a specified temperature.

Alarm Detection (ALARM)

Provides the ability to easily specify alarms on parameters that are obtained from I/O or from the results of other function block calculations.

Analog Input (AI)

Accesses a single analog measurement value and status from an I/O channel. The input value can be a transmitter's 4 to 20 mA signal or the digitally communicated primary or non-Primary Variable from a HART transmitter. The block supports mode control, block alarming, signal scaling, signal filtering, signal status calculation, and simulation.

Analog Output (AO)

Assigns an analog output value to a field device through a specified I/O channel. The block supports mode control, signal status calculation, and simulation.

Discrete Input (DI)

Accesses a single discrete measurement value and status from a two-state field device and makes the processed physical input available to other function blocks. The block supports mode control, signal status propagation, and simulation.

Discrete Output (DO)

Takes a binary setpoint and writes it to a specified I/O channel to produce an output signal. The block supports mode control, output tracking, simulation, and field device confirmation.

H1 Carrier Multiple Discrete Input (FFMDI)

Combines the eight channels of a Discrete Input card and makes them available as an 8-bit input to other function blocks.

H1 Carrier Multiple Discrete Output (FFMDO)

Takes an 8-bit setpoint and writes it to the I/O channels of a Discrete Output card on an H1 Carrier device.

Multiple Discrete Input (FFMDI_STD)

Accesses discrete input values from two-state field devices and makes the processed physical inputs available through eight discrete output parameters.

Multiple Discrete Output (FFMDO_STD)

The Fieldbus Multiple Discrete Output (FFMDO_STD) function block makes its eight input parameters available to the I/O subsystem.

Multiplexed Analog Input (FFMAI_RMT)

Connects higher density transmitters to a fieldbus segment.

Multiplexed Analog Output (FFMAO)

Makes eight input parameters available to the I/O subsystem.

Pulse Input (PIN)

Provides analog input values from Pulse Input channels on the Multifunction I/O card.

Smart HART Discrete Input

Accesses a single discrete input variable with status from a Wireless Discrete field device and makes the processed physical input available to other function blocks

Smart HART Discrete Output

Takes a setpoint and writes it to a specified I/O channel to produce an output signal.

Action (ACT)

Evaluates an expression when an input value is True. Mathematical functions, logical operators, and constants can be used in the expression.

And (AND)

Generates a discrete output value based on the logical AND of two to sixteen discrete inputs. The block supports signal status propagation.

Bi-directional Edge Trigger (BDE)

Generates a True (1) discrete pulse output when the discrete input makes a positive (False-to-True) or negative (True-to-False) transition since the last execution of the block. The block supports signal status propagation.

Boolean Fan Input (BFI)

Generates a discrete output based on the weighted binary sum, binary coded decimal (BCD) representation, transition state, or logical OR of one to sixteen discrete inputs. The block supports signal status propagation.

Boolean Fan Output (BFO)

Decodes a binary weighted floating point input to individual bits and generates a discrete output value for each bit (as many as sixteen outputs). The block supports signal status propagation.

Condition (CND)

Evaluates a single-line expression and generates a discrete output value when the expression is evaluated True (1) for longer than a specified time period. Mathematical functions, logical operators, and constants can be used in the expression.

Device Control (DC)

Provides setpoint control for multistate discrete devices. As many as four inputs and four outputs can be controlled. The basic functionality is augmented by an assortment of interlocks and device control options to customize the block's operation to your application. The block supports mode control, simulation, field device confirmation, and alarm limit detection.

Discrete Control Condition (DCC)

Evaluates up to 16 interlock conditions, 8 permissive conditions, and 8 force setpoint conditions. The output of an interlock or permissive condition can be delayed on, delayed off, or disabled. The output of a force setpoint condition can be delayed on or disabled.

Enhanced Device Control (EDC)

Provides setpoint control for multistate discrete devices such as motors, pumps, and block valves. The block compares the requested state (setpoint) to the actual state reported from the device and, after allowing time for the device to change state, detects alarm limits on any error. The basic functionality is augmented by an assortment of interlocks and device control options to customize the block's operation for an application.

Multiplexer (MLTX)

Selects one input value from as many as sixteen input values and places it at the output. The block supports signal status propagation.

Negative Edge Trigger (NDE)

Generates a True (1) discrete pulse output when the discrete input makes a negative (True-to-False) transition since the last execution of the block. The block supports signal status propagation.

Not (NOT)

Logically inverts a discrete input signal and generates a discrete output value. The block supports signal status propagation.

Or (OR)

Generates a discrete output value based on the logical OR of two to sixteen discrete inputs. The block supports signal status propagation.

Positive Edge Trigger (PDE)

Generates a True (1) discrete pulse output when the discrete input makes a positive (False-to-True) transition since the last execution of the block. The block supports signal status propagation.

Reset/Set Flip-flop (RS)

Generates a discrete output value based on NOR logic of reset and set inputs.

Set/Reset Flip-flop (SR)

Generates a discrete output value based on NAND logic of set and reset inputs.

Transfer (XFR)

Selects one of two analog input signals and transfers the selected input to the output after a specified time. The transfer from one input to another is smoothed with a linear ramp. The block supports signal status propagation.

Absolute Value

Provides the absolute value of an integer or floating-point input value.

Add (ADD)

Sums the values of two to sixteen inputs and generates an output value. The block supports signal status propagation.

Arithmetic (ARTHM)

Provides the ability to configure a range extension function for a primary input and applies the nine different arithmetic types as compensation to or augmentation of the range extended input.

Comparator (CMP)

Compares two values and sets a Boolean output based on that comparison.

Divide (DIV)

Divides one input value by another input value and generates an output value. The block supports signal status propagation.

Integrator (INT)

Integrates a variable over time. The block compares the integrated or accumulated value to pre-trip and trip limits and generates discrete output signals when the limits are reached. The integrated value can increment from zero or decrement from the trip value. The block has two inputs and can calculate and integrate net flow, as well as handling negative flow. The block supports mode control.

Multiply (MLTY)

Multiplies two to sixteen input values and generates an output value. The block supports signal status propagation.

Subtract (SUB)

Subtracts one input value from another input value and generates an output value. The block supports signal status propagation.

Counter (CTR)

Generates a discrete output of True (1) when the count reaches a specified trip value. The block functions as an incremental (up) counter or a decremental (down) counter. The block supports signal status propagation.

Date Time Event (DTE)

Provides Time Of Day Timer functions. Use the Timer functions to obtain date and time information in various formats, as well as manipulate date and time information. The function block allows scheduling future events at a specified date and time.

Off-delay Timer (OFFD)

Delays the transfer of a False (0) discrete input value to the output by a specified time period. The block supports signal status propagation.

On-delay Timer (OND)

Delays the transfer of a True (1) discrete input value to the output by a specified time period. The block supports signal status propagation.

Retentive Timer (RET)

Generates a True (1) discrete output after the input has been True for a specified time period. The elapsed time the input has been True and the output value are reset when the reset input is set True.

Timed Pulse (TP)

Generates a True (1) discrete output for a specified time duration when the input makes a positive (False-to-True) transition. The output remains True even when the input returns to its initial discrete value and returns to its original False value only when the output is True longer than the specified time duration.