Foundation™ Fieldbus Blocks SGCR PID DO AO 00809-0100-4783 English Rev.
Product Manual Foundation™ Fieldbus Blocks NOTICE Read this manual before working with the product. For personal and system safety, and for optimum product performance, make sure you thoroughly understand the contents before installing, using, or maintaining this product. Within the United States, Rosemount Inc. has two toll-free assistance numbers: Customer Central Technical support, quoting, and order-related questions.
Foundation Fieldbus Blocks Manual -ii
Table of Contents SECTION 1 Foundation™ Fieldbus Technology and Fieldbus Function Blocks Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 Function Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 Device Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 Block Operation . . . . . . . . . . . . . . . . . . . . . . . .
FOUNDATIONTM Fieldbus Blocks Manual SECTION 5 Discrete Input (DI) Function Block I/O Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2 Field Value Processing. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3 Alarm Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3 Block Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table of Contents SECTION 10 Signal Characterizer (SGCR) Function Block Block Execution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-3 Block Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4 Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4 Status Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4 SECTION 11 Diagnostics (ADB) Transducer Block Statistical Process Monitoring . .
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Section 1 FOUNDATION™ Fieldbus Technology and Fieldbus Function Blocks OVERVIEW This section introduces fieldbus systems that are common to all fieldbus devices. INTRODUCTION A fieldbus system is a distributed system composed of field devices and control and monitoring equipment integrated into the physical environment of a plant or factory. Fieldbus devices work together to provide I/O and control for automated processes and operations.
FOUNDATIONTM Fieldbus Blocks Manual Figure 1-1 illustrates the internal structure of a function block. When execution begins, input parameter values from other blocks are snapped-in by the block. The input snap process ensures that these values do not change during the block execution. New values received for these parameters do not affect the snapped values and will not be used by the function block during the current execution.
Introduction interoperability of function blocks within devices from various vendors. Additionally, human interface devices, such as operator consoles and computers, do not have to be programmed specifically for each type of device on the bus. Instead their displays and interactions with devices are driven from the device descriptions. Device descriptions may also include a set of processing routines called methods. Methods provide a procedure for accessing and manipulating parameters within a device.
FOUNDATIONTM Fieldbus Blocks Manual NETWORK COMMUNICATION Figure 1-2 illustrates a simple fieldbus network consisting of a single segment (link). Figure 1-2. Simple, Single-Link Fieldbus Network. Fieldbus Link LINK MASTER BASIC DEVICES AND/OR LINK MASTER DEVICES LAS = Link Active Scheduler Link Active Scheduler (LAS) All links have one and only one Link Active Scheduler (LAS). The LAS operates as the bus arbiter for the link. The LAS does the following: • recognizes and adds new devices to the link.
Introduction Device Addressing Fieldbus uses addresses between 0 and 255. Addresses 0 through 15 are reserved for group addressing and for use by the data link layer. For all Fisher-Rosemount fieldbus devices addresses 20 through 35 are available to the device. If there are two or more devices with the same address, the first device to start will use its programmed address. Each of the other devices will be given one of four temporary addresses between 248 and 251.
FOUNDATIONTM Fieldbus Blocks Manual Figure 1-3. Scheduled Data Transfer. LAS Schedule X Y Z CD(X,A) A B C A D A P S P S P S LAS = Link Active Scheduler P = Publisher S = Subscriber Device X CD = Compel Data DT = Data Transfer Packet Unscheduled Transfers Device Y Device Z FIELDBUS_0013 DT(A) Figure 1-4 diagrams an unscheduled transfer. Unscheduled transfers are used for things like user-initiated changes, including set point changes, mode changes, tuning changes, and upload/download.
Introduction Figure 1-5 shows an example of a link schedule. A single iteration of the link-wide schedule is called the macrocycle. When the system is configured and the function blocks are linked, a master link-wide schedule is created for the LAS. Each device maintains its portion of the link-wide schedule, known as the Function Block Schedule. The Function Block Schedule indicates when the function blocks for the device are to be executed.
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Section Analog Input (AI) Function Block FIELDBUS-FBUS_31A 2 OUT_D AI OUT OUT_D OUT = The block output value and status = Discrete output that signals a selected alarm condition The Analog Input (AI) function block processes field device measurements and makes them available to other function blocks. The output value from the AI block is in engineering units and contains a status indicating the quality of the measurement.
FOUNDATIONTM Fieldbus Blocks Manual TABLE 2-1. Definitions of Analog Input Function Block System Parameters Index Number Units Description ALARM_SUM 22 None ALERT_KEY 04 None BLOCK_ALM 21 None BLOCK_ERR 06 None CHANNEL 15 None FIELD_VAL 19 Percent GRANT_DENY 12 None HI_ALM 34 None HI_HI_ALM 33 None The summary alarm is used for all process alarms in the block. The cause of the alert is entered in the subcode field.
Analog Input (AI) Function Block TABLE 2-1.
FOUNDATIONTM Fieldbus Blocks Manual TABLE 2-1. Definitions of Analog Input Function Block System Parameters Index Number Units Description SIMULATE 09 None STRATEGY 03 None ST_REV 01 None TAG_DESC 02 None UPDATE_EVT 20 None VAR_INDEX 39 % of OUT Range VAR_SCAN 40 Seconds XD_SCALE 10 None A group of data that contains the current transducer value and status, the simulated transducer value and status, and the enable/disable bit.
Analog Input (AI) Function Block Figure 2-1. Analog Input Function Block Schematic Analog Measurement ALARM_TYPE Access Analog Meas. HI_HI_LIM HI_LIM LO_LO_LIM LO_LIM CHANNEL Alarm Detection OUT_D ALARM_HYS LOW_CUT SIMULATE L_TYPE FIELD_VAL Filter PV PV_FTIME MODE IO_OPTS Status Calc. OUT FIELDBUS-FBUS_02A Cutoff Convert STATUS_OPTS OUT_SCALE XD_SCALE NOTES: OUT = block output value and status. OUT_D = discrete output that signals a selected alarm condition. Figure 2-2.
FOUNDATIONTM Fieldbus Blocks Manual Signal Conversion You can set the signal conversion type with the Linearization Type (L_TYPE) parameter. You can view the converted signal (in percent of XD_SCALE) through the FIELD_VAL parameter. 100 × ( Channel Value – EU*@0% -) FIELD_VAL = ------------------------------------------------------------------------------------( EU*@100% – EU*@0% ) * XD_SCALE values You can choose from direct, indirect, or indirect square root signal conversion with the L_TYPE parameter.
Analog Input (AI) Function Block TABLE 2-3. BLOCK_ERR Conditions Condition Number 4 5 6 7 8 9 10 11 12 13 14 15 Modes Condition Name and Description Local Override Device Fault State Set Device Needs Maintenance Soon Input Failure/Process Variable has Bad Status: The hardware is bad, or a bad status is being simulated. Output Failure: The output is bad based primarily upon a bad input.
FOUNDATIONTM Fieldbus Blocks Manual Status Handling Normally, the status of the PV reflects the status of the measurement value, the operating condition of the I/O card, and any active alarm condition. In Auto mode, OUT reflects the value and status quality of the PV. In Man mode, the OUT status constant limit is set to indicate that the value is a constant and the OUT status is Good.
Analog Input (AI) Function Block Troubleshooting Refer to Table 2-4 to troubleshoot any problems that you encounter. TABLE 2-4. Troubleshooting Symptom Mode will not leave OOS Possible Causes Target mode not set.
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Section 3 Analog Output (AO) Function Block BKCAL_OUT AO fieldbus-fbus_32a CAS_IN OUT CAS_IN = The remote setpoint value from another function block. BKCAL_OUT = The value and status required by the BKCAL_IN input of another block to prevent reset windup and to provide bumpless transfer to closed loop control. OUT = The block output and status. The Analog Output (AO) function block assigns an output value to a field device through a specified I/O channel.
FOUNDATIONTM Fieldbus Blocks Manual Parameters Setting the Output Units Description READBACK EU of XD_SCALE The measured or implied actuator position associated with the OUT value. SIMULATE EU of XD_SCALE Enables simulation and allows you to enter an input value and status. SP EU of PV_SCALE The target block output value (setpoint). SP_HI_LIM EU of PV_SCALE The highest setpoint value allowed. SP_LO_LIM EU of PV_SCALE The lowest setpoint value allowed.
Analog Output (AO) Function Block Figure 3-1. Analog Output Function Block Schematic RCAS_OUT RCAS_IN SP_RATE_DN SP_RATE_UP Operator Setpoint CAS_IN SP HI/LO Limit BKCAL_OUT READ_BACK PV Convert and Status Calculation SP Rate Limit OUT SP_WRK SP_LO_LIM SP_HI_LIM PV_SCALE IO_OPTS MODE SIMULATE Access Analog Output Access Analog Input Position Feedback fieldbus-fbus_07a Shed Mode CHANNEL Analog Output Figure 3-2.
FOUNDATIONTM Fieldbus Blocks Manual Setpoint Selection and Limiting To select the source of the SP value use the MODE attribute. In Automatic (Auto) mode, the local, manually-entered SP is used. In Cascade (Cas) mode, the SP comes from another block through the CAS_IN input connector. In RemoteCascade (RCas) mode, the SP comes from a host computer that writes to RCAS_IN. The range and units of the SP are defined by the PV_SCALE attribute.
Analog Output (AO) Function Block Action On Fault Detection To define the state to which you wish the valve to enter when the CAS_IN input detects a bad status and the block is in CAS mode, configure the following parameters: FSTATE_TIME: The length of time that the AO block will wait to position the OUT value to the FSTATE_VAL value upon the detection of a fault condition.
FOUNDATIONTM Fieldbus Blocks Manual Status Handling Output or readback fault detection are reflected in the status of PV, OUT, and BKCAL_OUT. A limited SP condition is reflected in the BKCAL_OUT status. When simulation is enabled through the SIMULATE attribute, you can set the value and status for PV and READBACK. When the block is in Cas mode and the CAS_IN input goes bad, the block sheds mode to the next permitted mode.
Section 4 Arithmetic Function Block IN IN_LO OUT ARTHM IN_1 IN_2 IN_3 The Arithmetic function block provides the ability to configure a range extension function for a primary input and applies the nine (9) different arithmetic types as compensation to or augmentation of the range extended input. All operations are selected by parameter and input connection.
FOUNDATIONTM Fieldbus Function Blocks TABLE 4-1.
Arithmetic Function Block Figure 4-2.
FOUNDATIONTM Fieldbus Function Blocks Modes The ARTHM block supports the following modes: Manual (Man)—. Automatic (Auto)—. Out of Service (OOS)—. The target mode of a block bay be restricted to one or more of the supported modes. Status Handling IN_x Use Bad IN_x Use Uncertain IN_LO Use Uncertain IN Use Uncertain For complete descriptions of supported input options, refer to the Option Bitstring Parameters topic.
Section Discrete Input (DI) Function Block DI OUT_D OUT_D fieldbus-fbus_33a 5 = The discrete output value and status The Discrete Input (DI) function block processes a single discrete input from a field device and makes it available to other function blocks. You can configure inversion and alarm detection on the input value. The Discrete Input function block supports mode control, signal status propagation, and simulation.
FOUNDATIONTM Fieldbus Blocks Manual Parameters FIGURE 5-2. Discrete Input Function Block Schematic Units Description MODE None The mode record of the block. Contains the actual, target, permitted, and normal modes. See System Support OUT_D None The discrete output value and status. PV_D None The discrete process variable used in block execution. SIMULATE_D None Enables simulation and allows you to enter an input value and status when SIMULATE_IN_D is not connected.
Discrete Input (DI) Function Block Field Value Processing You can configure the Invert I/O option (IO_OPTS) to process FIELD_VAL_D. The invert option indicates whether or not the discrete input is logically inverted before it is stored in the process variable (PV_D). The output of the Invert processor is PV_D. This value goes to the mode switch where it becomes OUT_D when the mode is Auto. OUT_D is also tested for an alarm state.
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Section Discrete Output (DO) Function Block BKCAL_OUT_D fieldbus-fbus_32a 6 CAS_IN_D DO OUT_D CAS_IN_D = The remote setpoint value from another function block. BKCAL_OUT_D = The output value and status required by BKCAL_IN_D input of another block for output tracking. OUT_D = The discrete output value and status The Discrete Output (DO) function block processes a discrete setpoint and saves it to a specified channel to produce an output signal.
FOUNDATIONTM Fieldbus Blocks Manual TABLE 6-1. Discrete Output Function Block System Parameters Parameters Units Description BKCAL_OUT_D None The value and status required by the BKCAL_IN_D input of another block for output tracking. BLOCK_ERR None The summary of active error conditions associated with the block. The supported block errors in the Discrete Output function block are Simulate active, Input failure/process variable has Bad status, Output failure, readback failed, and Out of service.
Discrete Output (DO) Function Block Setting the Output To set the output for the DO block, you must first set the mode to define the manner in which the block determines its setpoint. In Cascade mode, the setpoint equals the input value (CAS_IN_D). In Automatic or Manual mode, the setpoint must be entered manually by the user. In Remote Cascade mode, the setpoint is determined by a host computer that is writing to the RCAS_IN_D parameter.
FOUNDATIONTM Fieldbus Blocks Manual Block Errors The following conditions are reported in the BLOCK_ERR attribute: Simulate active – SIMULATE_D is enabled; therefore, PV_D is not real. Input failure/process variable has Bad status – The readback value is bad. Output failure – The output hardware or the configured channel is invalid. Readback failed – The hardware providing readback is bad. Out of service – The block is not being processed.
Section Integrator (INT) Function Block IN_1 OUT IN_2 INT REV_FLOW1 REV_FLOW2 OUT_PTRIP OUT_TRIP N_RESET RESET_IN IN_1 IN_2 REV_FLOW1 REV_FLOW2 RESET_IN OUT OUT_PTRIP OUT_TRIP N_RESET = The first input value and status. = The second input value and status. = The discrete input that specifies whether IN_1 is positive or negative. = The discrete input that specifies whether IN_1 is positive or negative. = The discrete input that resets the integrator and holds reset until released.
FOUNDATIONTM Fieldbus Blocks Manual Figure 7-1. Integrator Function Block Schematic –1 REV_FLOW1 Reverse IN_1 Convert Rate Forward INTEG_OPTS N_RESET Integrate Add OUT INTEG_TYPE RESET_IN Compare UNIT_CONV OUT_TRIP Forward Compare OUT_PTRIP Reverse PRE_TRIP SP REV_FLOW2 –1 TABLE 7-1. Integrator Function Block System Parameters Index 7-2 Parameters Definition 1 ST_REV 2 TAG_DESC 3 STRATEGY 4 ALERT_KEY The revision level of the static data associated with the function block.
Integrator (INT) Function Block TABLE 7-1.
FOUNDATIONTM Fieldbus Blocks Manual Block Execution The INT function block integrates a variable over time. The integrated or accumulated value (OUT) is compared to pre-trip and trip limits. When the limits are reached, discrete output signals are generated (OUT_PTRIP and OUT_TRIP). You can choose one of six integrator types that determine whether the integrated value increases from zero or decreases from the trip value. The block has two inputs and can integrate positive, negative, or net flow.
Integrator (INT) Function Block Specifying Rate Time Base The time unit parameters (TIME_UNIT1 and TIME_UNIT2) specify the rate time base of the inputs (IN_1 and IN_2, respectively).
FOUNDATIONTM Fieldbus Blocks Manual 0 to ? - demand reset – Counts upward and is reset when RESET_IN or OP_CMD_INT transitions to True. 0 to ? - periodic & demand reset – Counts upward and is reset periodically or by RESET_IN. Trip and Pre-trip Action When the integration value reaches SP – PRE_TRIP (or 0 – PRE_TRIP, depending on the INTEG_TYPE), OUT_PTRIP is set. When the integration value reaches the trip target value (SP or 0), OUT_TRIP is set. OUT_PTRIP remains set until SP or 0 is reached.
Integrator (INT) Function Block Status Handling The output status calculation is based on the accumulation of input statuses. The calculation includes the accumulations for both input channels when IN_2 is enabled. The input statuses are accumulated in Good and Bad groups. An input status of Uncertain is interpreted as a Bad status for the output status calculation. Each time the function block executes, the input status is incremented in the appropriate group.
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Section 8 Input Selector (ISEL) Function Block IN_1 IN_2 OUT IN_3 IN_4 DISABLE_1 DISABLE_2 ISEL SELECTED fieldbus-fbus_40a DISABLE_3 DISABLE_4 OP_SELECT IN (1-4) DISABLE (1-4) OP_SELECT TRK_VAL SELECTED OUT = Input used in the selection algorithm. = Discrete input used to enable or disable the associated input channel. = Input used to override algorithm. = The value after scaling applied to OUT in Local Override mode. = The selected channel number. = The block output and status.
FOUNDATIONTM Fieldbus Blocks Manual TABLE 8-1. Input Selector Function Block System Parameters Parameter Index Number BLOCK_ERR 06 OUT OUT_RANGE 07 08 GRANT_DENY 09 STATUS_OPTIONS 10 IN_1 IN_2 IN_3 IN_4 DISABLE_1 DISABLE_2 DISABLE_3 DISABLE_4 SELECT_TYPE MIN_GOOD 11 12 13 14 15 16 17 18 19 20 SELECTED OP_SELECT UPDATE_EVT BLOCK_ALM 21 22 23 24 Description This parameter reflects the error status associated with the hardware or software components associated with a block.
Input Selector (ISEL) Function Block Block Errors Table 8-2 lists conditions reported in the BLOCK_ERR parameter. Conditions in italics are inactive for the ISEL block and are given here only for your reference. TABLE 8-2. BLOCK_ERR Conditions Condition Number 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Modes Condition Name and Description Other: The output has a quality of uncertain. Block Configuration Error Link Configuration Error Simulate Active Local Override: The actual mode is LO.
FOUNDATIONTM Fieldbus Blocks Manual Block Execution The ISEL function block reads the values and statuses of as many as four inputs. To specify which of the six available methods (algorithms) is used to select the output, configure the selector type parameter (SEL_TYPE) as follows: • max selects the maximum value of the inputs. • min selects the minimum value of the inputs. • avg calculates the average value of the inputs.
Input Selector (ISEL) Function Block Troubleshooting Refer to Table 8-3 to troubleshoot any problems that you encounter. TABLE 8-3. Troubleshooting Symptom Mode will not leave OOS Possible Causes Target mode not set. Configuration error Resource block Schedule Status of output is BAD Inputs OP selected Min good Block alarms will not work. Features Notification Status Options Corrective Action Set target mode to something other than OOS. BLOCK_ERR will show the configuration error bit set.
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Section 9 Proportional/Integral/Derivative (PID) Function Block BKCAL_IN BKCAL_OUT FF_VAL PID IN FIELDBUS-FBUS_34A CAS_IN OUT TRK_IN_D TRK_VAL BKCAL_IN CAS_IN FF_VAL IN = The analog input value and status from another block’s BKCAL_OUT output that is used for backward output tracking for bumpless transfer and to pass limit status. = The remote setpoint value from another function block. = The feedforward control input value and status.
FOUNDATIONTM Fieldbus Blocks Manual To further customize the block for use in your application, you can configure filtering, feedforward inputs, tracking inputs, setpoint and output limiting, PID equation structures, and block output action. Table 9-1 lists the PID block parameters and their descriptions, units of measure, and index numbers, and Figure 9-1 on page 9-5 illustrates the internal components of the PID function block. TABLE 9-1. PID Function Block System Parameters.
Proportional/Integral/Derivative (PID) Function Block TABLE 9-1. PID Function Block System Parameters.
FOUNDATIONTM Fieldbus Blocks Manual TABLE 9-1. PID Function Block System Parameters. Index Number Units Description STRATEGY 03 None ST_REV 01 None STRUCTURE. CONFIG TAG_DESC TRK_IN_D TRK_SCALE 75 None The strategy field can be used to identify grouping of blocks. This data is not checked or processed by the block. The revision level of the static data associated with the function block. The revision value will be incremented each time a static parameter value in the block is changed.
Proportional/Integral/Derivative (PID) Function Block Figure 9-1.
FOUNDATIONTM Fieldbus Blocks Manual Operator Setpoint Auto Man Cas SP_HI_LIM SP_LO_LIM SP_RATE_UP SP_RATE_DN Setpoint Limiting Rate Limiting Auto Man Cas FIELDBUS-FBUS_01A Figure 9-2. PID Function Block Setpoint Selection Filtering The filtering feature changes the response time of the device to smooth variations in output readings caused by rapid changes in input.
Proportional/Integral/Derivative (PID) Function Block Bumpless Transfer and Setpoint Tracking You can configure the method for tracking the setpoint by configuring the following control options (CONTROL_OPTS): SP-PV Track in Man — Permits the SP to track the PV when the target mode of the block is Man. SP-PV Track in LO or IMan — Permits the SP to track the PV when the actual mode of the block is Local Override (LO) or Initialization Manual (IMan).
FOUNDATIONTM Fieldbus Blocks Manual Reset Limiting The PID function block provides a modified version of feedback reset limiting that prevents windup when output or input limits are encountered, and provides the proper behavior in selector applications. Block Errors Table 9-3 lists conditions reported in the BLOCK_ERR parameter. Conditions in italics are inactive for the PID block and are given here only for your reference. TABLE 9-3.
Proportional/Integral/Derivative (PID) Function Block Alarm Detection A block alarm will be generated whenever the BLOCK_ERR has an error bit set. The types of block error for the AI block are defined above. Process alarm detection is based on the PV value.
FOUNDATIONTM Fieldbus Blocks Manual Troubleshooting Refer to Table 9-4 to troubleshoot any problems that you encounter. TABLE 9-4. Troubleshooting Symptom Mode will not leave OOS Possible Causes Target mode not set. Configuration error Resource block Schedule Mode will not leave IMAN Back Calculation Mode will not change to AUTO Target mode not set. Input Mode will not change to CAS Target mode not set.
Proportional/Integral/Derivative (PID) Function Block TABLE 9-4. Troubleshooting Symptom Mode sheds from ROUT to MAN Possible Causes Remote output value Shed timer Process and/or block alarms will not work. Features Notification Status Options Corrective Action Host system is not writing ROUT_IN with a quality and status of “good cascade” within shed time (see 2 below). The mode shed timer, SHED_RCAS, in the resource block is set too low. Increase the value. FEATURES_SEL does not have Alerts enabled.
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Section Signal Characterizer (SGCR) Function Block IN_1 IN_2 fieldbus-fbus_36a 10 OUT_1 SGCR IN_1 and IN_2 OUT_1 OUT_2 OUT_2 = The input values to the block. = The output associated with IN_1. = The output associated with IN_2. The Signal Characterizer (SGCR) function block characterizes or approximates any function that defines an input/output relationship. The function is defined by configuring as many as twenty X,Y coordinates.
FOUNDATIONTM Fieldbus Blocks Manual TABLE 10-1. Signal Characterizer Function Block System Parameters Index Parameter Number Description 1 ST_REV 2 3 TAF_DESC STRATEGY 4 ALERT_KEY 5 MODE_BLK 6 BLOCK_ER R 7 8 9 OUT1 OUT2 X_SCALE 10 Y_SCALE 11 GRANT_DE NY 12 13 14 IN1 IN2 SWAP_2 15 CURVE_X 16 CURVE_Y 17 UPDATE_EV T BLOCK _ALM 18 The revision level of the static data associated with the function block.
Signal Characterizer (SGCR) Function Block Block Execution For any given input value, the SGCR block determines where the input lies in CURVE_X and calculates the slope of that segment using the point-slope method: y = mx + b Where: m: b: slope of the line y-intercept of the line Using this formula, the block derives an output value that corresponds to the input. When the input lies beyond the range configured in CURVE_X, the output is clamped to the corresponding limit in the CURVE_Y array.
FOUNDATIONTM Fieldbus Blocks Manual SWAP_2 Attribute The SWAP_2 attribute swaps the X and Y axes used for OUT_2. When the SWAP_2 attribute is True, IN_2 references the CURVE_Y values and OUT_2 references the CURVE_X values. In addition, the IN_2 units change to Y_UNITS and the OUT_2 units change to X_UNITS. The block sets a configuration error when SWAP_2 is True and the CURVE_Y elements are not configured in an increasing manner.
Section 11 Diagnostics (ADB) Transducer Block The diagnostics block (ADB) is a transducer block that contains two different algorithms, Plugged Impulse Line Detection and Statistical Process Monitoring. Learning, detection and configuration are the three different phases to the Plugged Impulse Line and Statistical Process Monitoring. TABLE 11-1.
FOUNDATIONTM Fieldbus Blocks Manual Learning Phase In the learning phase of Statistical Process Monitoring, the algorithm establishes a baseline of the mean and dynamics of a Statistical Process Monitoring variable. The baseline data is compared to current data for calculating any changes in mean or dynamics of the Statistical Process Monitoring variables. Monitoring Phase The monitoring phase starts after a “Training Complete” message is posted for the variable.
Diagnostics (ADB) Transducer Block Parameter Index Units Description SPM2_PARAM_INDEX 835 NA OD Parameter index for the Block tag that is entered SPM2_STATUS 836 NA Status of the SPM2 Statistical Process Monitoring SPM2_TIMESTAMP 837 time Timestamp of last SPM2 Statistical Process Monitoring status change SPM2_USER_COMMAND 838 NA User control for the Statistical Process Monitoring session SPM2_MEAN 839 NA Last mean of SPM2 SPM2_MEAN_CHANGE 840 % Percent change in SPM2 mean with re
FOUNDATIONTM Fieldbus Blocks Manual PLUGGED IMPULSE LINE DETECTION Parameter Index Units Description SPM4_USER_COMMAND 868 NA User control for the Statistical Process Monitoring session SPM4_MEAN 869 NA Last mean of SPM4 SPM4_MEAN_CHANGE 870 % Percent change in SPM4 mean with respect to baseline mean SPM4_STDEV 871 NA Last Stdev of SPM4 SPM4_STDEV_CHANGE 872 % Change in SPM4 Stdev with respect to baseline Stdev SPM4_BASELINE_MEAN 873 NA Baseline mean for SPM4 SPM4_BASELINE_STDE
Diagnostics (ADB) Transducer Block TABLE 11-3.
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Appendix A ANALOG INPUT (AI) FUNCTION BLOCK Applications The configuration of the AI function block and its associated output channels depends on the specific application. A typical configuration for the AI block involves the following parameters: CHANNEL If the device supports more than one measurement, verify that the selected channel contains the appropriate measurement or derived value. L_TYPE Select Direct when the measurement is already in the engineering units that you want for the block output.
FOUNDATIONTM Fieldbus Blocks Manual Application Example: Pressure Transmitter used to Measure Level in an Open Tank Situation #1 The level of an open tank is to be measured using a pressure tap at the bottom of the tank. The level measurement will be used to control the level of liquid in the tank. The maximum level at the tank is 16 ft. The liquid in the tank has a density that makes the level correspond to a pressure of 7.0 psi at the pressure tap (see Figure A-2). Figure A-2.
Applications Situation #2 The transmitter in situation #1 is installed below the tank in a position where the liquid column in the impulse line, when the tank is empty, is equivalent to 2.0 psi (see Figure A-4). Figure A-4. Situation #2 Diagram 16 ft FIELDBUS-3244MV-3244A_02A Empty Tank 0 ft 2.0 psi measured at the transmitter Solution Section : Analog Input Function Block Configuration for a Pressure Transmitter used in Level Measurement (Situation #2) lists the appropriate configuration settings.
FOUNDATIONTM Fieldbus Blocks Manual Figure A-5. Function Block Diagram for a Differential Pressure Transmitter Used in a Flow Measurement Analog Measurement AI Function Block BKCAL_IN OUT_D OUT ANALOG OUTPUT (AO) FUNCTION BLOCK BKCAL_OUT PID Function Block AO Function Block IN The configuration of an AO function block and its associated output channels depends on the specific application.
Applications Figure A-6. Analog Output Function Block Diagram Example BKCAL_IN PID Function Block AI Function Block OUT OUT AO Function Block CAS_IN OUT CAS_IN Output ARITHMETIC (ARTH) FUNCTION BLOCK fieldbus-fbus_09a BKCAL_OUT The Arithmetic function block can be used to calculate tank level changes based on greatly changing temperature conditions in devices that depend on the physical properties of the fluid.
FOUNDATIONTM Fieldbus Blocks Manual The calculation is done by applying the level signal to the IN connector, the liquid temperature to the IN_1 connector, and the ambient air temperature to the IN_2 connector. Select the Arithmetic type (ARITH_TYPE) of Flow Compensation - Linear. This allows a ratio to be set up that increases the level indication at block output for an increase in the tank temperature relative to ambient temperature. Figure A-7.
Applications If there is a divide by zero and the numerator is positive, f is set to COMP_HI; if the numerator is negative, then f is set to COMP_LO. The square root of a negative value will equal the negative of the square root of the absolute value. Imaginary roots are not supported.
FOUNDATIONTM Fieldbus Blocks Manual Compensation inputs which are not configured are not used in the calculation. PV is always used. • Fourth-Order Polynomial func = PV + t(1) 2 + t(2) 3 + t(3) 4 • Simple HTG Compensate Level PV – t(1) func = ----------------------PV – t(2) If there is a divide by zero and the numerator is positive, function will be limited to COMP_HI; if the numerator is negative, function will be limited to COMP_LO.
Applications DISCRETE OUTPUT (DO) FUNCTION BLOCK More information to come. INPUT SELECTOR (ISEL) FUNCTION BLOCK You can use the ISEL function block to select the maximum temperature input from four inputs and send it to a PID function block to control a process water chiller (see Figure A-8) or you can use the block to calculate the average temperature of the four inputs (see Figure A-9). Figure A-8.
FOUNDATIONTM Fieldbus Blocks Manual INTEGRATOR (INT) FUNCTION BLOCK The Integrator function block is useful for calculating total flow, total mass, or volume over time. You can also use it to calculate total power, given the total energy. Application Example: Flow Integration To totalize flow over a one-hour period, configure INTEG_TYPE = 0 to ? - periodic reset and configure CLOCK_PER to 3600. Figure A-11 illustrates the correct function block configuration.
Applications The MODE parameter is a switch that indicates the target and actual mode of operation. Mode selection has a large impact on the operation of the PID block: • Manual mode allows the operator to set the value of the loop output signal directly. • Automatic mode allows the operator to select a setpoint for automatic correction of error using the GAIN, RESET, and RATE tuning values. • Cascade and Remote Cascade modes use a setpoint from another block in a cascaded configuration.
FOUNDATIONTM Fieldbus Blocks Manual The PID loop uses TT101 as an input and provides a signal to the analog output TCV101. The BKCAL_OUT of the AO block and the BKCAL_IN of the PID block communicate the status and quality of information being passed between the blocks. The status indication shows that communications is functioning and the I/O is working properly. Figure A-13 illustrates the correct function block configuration.
Applications Figure A-15. Function Block Diagram for Feedforward Control Outlet Temperature Input AI Function Block BKCAL_IN IN OUT FF_VAL BKCAL_OUT PID Function Block OUT CAS_IN TC101 TT101 AO Function Block OUT TCV101 AI Function Block FIELDBUS-FBUS_17A Inlet Temperature Input OUT TT100 A slave loop is added to a basic PID control configuration to measure and control steam flow to the steam heater. Variations in the steam pressure cause the temperature in the heat exchanger to change.
FOUNDATIONTM Fieldbus Blocks Manual If the flow is controlled, steam pressure variations will be compensated before they significantly affect the heat exchanger temperature. The output from the master temperature loop is used as the setpoint for the slave steam flow loop. The BKCAL_IN and BKCAL_OUT connections on the PID blocks are used to prevent controller windup on the master loop when the slave loop is in Manual or Automatic mode, or it has reached an output constraint.
Applications You can use the PID function block with other function blocks for complex control strategies. Figure A-18 illustrates the function block diagram for cascade control with override. Application Example: Cascade Control with Override When configured for cascade control with override, if one of the PID function blocks connected to the selector inputs is deselected, that PID block filters the integral value to the selected value (the value at its BKCAL_IN).
FOUNDATIONTM Fieldbus Blocks Manual SIGNAL CHARACTERIZER (SGCR) FUNCTION BLOCK A-16 You can use the SGCR function block as a curve fitting function. For example, you can scale a 4 to 20 mA input signal to a 0 to 100% output value using the block. You can also use the block to convert measurements from a split-range or other nonlinear device or from a dual-temperature control device used for both heating and cooling.
1 A Address . . . . . . . . . . . . . . . . . . 1-5 temporary . . . . . . . . . . . . 1-5 AI block parameters ALARM_TYPE . . . . . 2-8 BLOCK_ERR . . . . . . 2-6 CHANNEL . . . . . . . . A-1 IO_OPTS . . . . . . . . . . 2-6 L_TYPE . . . . . . . 2-6, A-1 LOW_CUT . . . . . . . . . 2-6 OUT_D . . . . . . . . . . . 2-8 OUT_SCALE . . . 2-6, A-1 PV_FTIME . . . . . . . . 2-5 SCALING . . . . . . . . . A-1 VAR_INDEX . . . . . . . 2-8 VAR_SCAN . . . . . . . . 2-8 XD_SCALE . . . . 2-6, A-1 status . . . . . . . . . . . . .
Foundation Fieldbus Blocks Manual definition . . . . . . . . . . . . . Live List definition . . . . . . . . . . . . . LO PID block . . . . . . . . . . . . . LO_LIM PID block . . . . . . . . . . . . . LO_LO_LIM PID block . . . . . . . . . . . . . LO_LO_PRI PID block . . . . . . . . . . . . . LO_PRI PID block . . . . . . . . . . . . . Local Override mode PID block . . . . . . . . . . . . . LOW_CUT AI block . . . . . . . . . . . . . . 9-7 OUT_SCALE AI block . . . . . . . . . . 2-6, A-1 PID block . . . . . .
Index SP_HI_LIM PID block . . . . . . . . . . . . . SP_LO_LIM PID block . . . . . . . . . . . . . SP_RATE_DN PID block . . . . . . . . . . . . . SP_RATE_UP PID block . . . . . . . . . . . . . SP_WRK PID block . . . . . . . . . . . . . Status AI block . . . . . . . . . . . . . . Status handling PID block . . . . . . . . . . . . . STATUS_OPTS ISEL block . . . . . . . . . . . . STRUCTURE PID block . . . . . . . . . . . . . Subscriber (S) . . . . . . . . . . . . . System management . . . . . . .
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