SIS Function Blocks - Parameters: DeltaV BOL 9.3

SIS Function Blocks - Parameters

Inside this topic

Parameter Characteristics
Parameter Data Types
Status Handling
BLOCK_ERR Parameter Bits
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Parameters are data used in SIS function blocks to perform calculations and logic. Parameters can be described by the type of information they provide to the function block:

Input parameters contain values from other function blocks.
Output parameters are the values calculated by the function block.
Contained parameters are used only within the function block for calculation, logic, and status determination functions.

Parameter Characteristics

SIS function block parameters can have one or more characteristics that determine how and when the parameter values can be written and how the values are restored after a download or power failure. The characteristics of a block are not configurable. The parameter table for each function block contains parameter characteristics information. The characteristics definitions are:

Configurable — These parameters can be given values during configuration.
Writeable — The value of these parameters can be changed during runtime.
Preserved on Download — The Logic Solver supports total downloads only. When a Logic Solver is downloaded these parameters are copied from the existing block into the newly downloaded block to provide matching, rather than initializing, behavior following a download.
Restored on Restart — The current value is stored in non-volatile memory. After a restart, the values for these parameters are restored from non-volatile memory.

Note Restart in this context is the resumption of processing after power is restored to a Logic Solver following a power loss or after the Logic Solver is reset. If the Logic Solver was removed from the carrier during the power loss or the duration of the power loss was more than approximately 24 hours, the Restored on Restart behavior does not occur.

Restored on Restart parameters are not restored if they are wired to (written to).

SIS function block parameters are similar to DeltaV function block parameters in several ways. Refer to Function Blocks - Parameters for information on the following topics:

Creating Custom Engineering Unit Descriptions
Parameter Filtering

Parameter Data Types

Outputs from one function block can be brought into another function block as parameters for calculation or logic functions and sent to other function blocks.

There are a number of data types that SIS function block parameter can have:

Option Bitstring – an unsigned 16-bit integer that contains bit-encoded information that specifies control strategy options, I/O value processing, status handling and processing, or the type of control logic used in the block.
I/O Reference – a value that assigns channel names in an I/O device.
Discrete with Status – an unsigned 8-bit integer value with a status indicator. A value of 0 (zero) means False. A value between 1 and 255 means True.
Simulate Discrete – a discrete value that enables/disables simulation and a simulated discrete value and status.
Floating Point – a number whose decimal point location is not fixed. This allows the calculation to consider significant digits information.
Scaling – a number that is used to convert a floating point value to the required engineering units.
Simulate Floating Point – a discrete value that enables/disables simulation and a simulated floating point value and status.
8-bit Unsigned integer – a whole number without a positive or negative sign associated with it.
Boolean – a True or False value
String – as many as 255 characters
32-bit Unsigned Integer – a whole number without a positive or negative sign associated with it.
Alarm – a value of 0 or 1 (inactive or active) indicating the state of an alarm.

Because data of different types can be transmitted between function blocks, there are rules that govern data compatibility and conversions. The data conversions are performed automatically by the DeltaV software.

The following table lists parameter data type compatibility information:

Function Block Parameter Compatibility

Source Data Type	Destination Data Type	Comments
8-bit Unsigned Integer	8-bit Unsigned Integer	Bit copy full parameter.
	16-bit Unsigned Integer	Current value converted; no data loss.
	32-bit Unsigned Integer	Current value converted; no data loss.
	32-bit Unsigned Integer with status	Current value converted; no data loss.
	Floating Point	Current value converted; no data loss.
	Floating Point with status	Current value converted; no data loss.
	Discrete with Status	Current value converted; no data loss.
	Boolean	Current value set to zero if source current value equals zero. Else, current value set to one.
	Boolean with status	Current value set to zero if source current value equals zero. Else, current value set to one.
	Option Bitstring	Current value converted; no data loss.
	Named Set	Current value converted; no data loss.
16-bit Unsigned Integer	8-bit Unsigned Integer	Current value converted; clamped to extremes of destination type.
	16-bit Unsigned Integer	Bit copy full parameter.
	32-bit Unsigned Integer	Current value converted; no data loss.
	32-bit Unsigned Integer with status	Current value converted; no data loss.
	Floating Point	Current value converted; no data loss.
	Floating Point with status	Current value converted; no data loss.
	Discrete with status	Current value converted; clamped to extremes of destination type.
	Boolean	Current value set to zero if source current value equals zero. Else, current value set to one.
	Boolean with status	Current value set to zero if source current value equals zero. Else, current value set to one.
	Option Bitstring	Current value converted; no data loss.
	Named Set	Current value converted; clamped to extremes of destination type.
32-bit Unsigned Integer	8-bit Unsigned Integer	Current value converted; clamped to extremes of destination type.
	16-bit Unsigned Integer	Current value converted; clamped to extremes of destination type.
	32-bit Unsigned Integer	Bit copy full parameter.
	32-bit Unsigned Integer with status	Current value converted; no data loss.
	Floating Point	Current value converted; precision loss.
	Floating Point with status	Current value converted; precision loss.
	Discrete with status	Current value converted; clamped to extremes of destination type.
	Boolean	Current value set to zero if source current value equals zero. Else, current value set to one.
	Boolean with status	Current value set to zero if source current value equals zero. Else, current value set to one.
	Option Bitstring	Current value converted; clamped to extremes of destination type.
	Named Set	Current value converted; clamped to extremes of destination type.
32-bit Unsigned Integer with status	8-bit Unsigned Integer	Current value converted; clamped to extremes of destination type.
	16-bit Unsigned Integer	Current value converted; clamped to extremes of destination type.
	32-bit Unsigned Integer	Current value converted; clamped to extremes of destination type.
	32-bit Unsigned Integer with status	Bit copy full parameter.
	Floating Point	Current value converted; precision loss.
	Floating Point with status	Current value converted; precision loss.
	Discrete with status	Current value converted; clamped to extremes of destination type.
	Boolean	Current value set to zero if source current value equals zero. Else, current value set to one.
	Boolean with status	Current value set to zero if source current value equals zero. Else, current value set to one.
	Option Bitstring	Current value converted; clamped to extremes of destination type.
	Named Set	Current value converted; clamped to extremes of destination type.
Boolean	8-bit Unsigned Integer	Current value converted; no data loss.
	16-bit Unsigned Integer	Current value converted; no data loss.
	32-bit Unsigned Integer	Current value converted; no data loss.
	32-bit Unsigned Integer with status	Current value converted; no data loss.
	Floating Point	Current value converted; no data loss.
	Floating Point with status	Current value converted; no data loss.
	Discrete with status	Current value converted; no data loss.
	Boolean	Bit copy full parameter.
	Boolean with status	Current value converted; no data loss.
	Option Bitstring	Current value converted; no data loss.
	Named Set	Current value converted; no data loss.
Boolean with status	8-bit Unsigned Integer	Current value converted; no data loss.
	16-bit Unsigned Integer	Current value converted; no data loss.
	32-bit Unsigned Integer	Current value converted; no data loss.
	32-bit Unsigned Integer with status	Current value converted; no data loss.
	Floating Point	Current value converted; no data loss.
	Floating Point with status	Current value converted; no data loss.
	Discrete with status	Current value converted; no data loss.
	Boolean	Current value converted; no data loss.
	Boolean with status	Bit copy full parameter.
	Option Bitstring	Current value converted; no data loss.
	Named Set	Current value converted; no data loss.
Floating Point	8-bit Unsigned Integer	Current value converted; clamped to extremes of destination type.
	16-bit Unsigned Integer	Current value converted; clamped to extremes of destination type.
	32-bit Unsigned Integer	Current value converted; clamped to extremes of destination type.
	32-bit Unsigned Integer with status	Current value converted; clamped to extremes of destination type.
	Floating Point	Bit copy full parameter.
	Floating Point with status	Current value converted; no data loss.
	Discrete with status	Current value converted; clamped to extremes of destination type.
	Boolean	Current value set to zero if source current value equals zero. Else, current value set to one.
	Boolean with status	Current value set to zero if source current value equals zero. Else, current value set to one.
	Option Bitstring	Current value converted; clamped to extremes of destination type.
	Named Set	Current value converted; clamped to extremes of destination type.
Floating Point with status	8-bit Unsigned Integer	Current value converted; clamped to extremes of destination type.
	16-bit Unsigned Integer	Current value converted; clamped to extremes of destination type.
	32-bit Unsigned Integer	Current value converted; clamped to extremes of destination type.
	32-bit Unsigned Integer with status	Current value converted; clamped to extremes of destination type.
	Floating Point	Current value converted; no data loss.
	Floating Point with status	Bit copy full parameter.
	Discrete with status	From 0 to 255, the current value is converted to integer. If the current value becomes greater than 255, the converted value remains at its previous value.
	Boolean	Current value set to zero if source current value equals zero. Else, current value set to one.
	Boolean with status	Current value set to zero if source current value equals zero. Else, current value set to one.
	Option Bitstring	Current value converted; clamped to extremes of destination type.
	Named Set	Current value converted; clamped to extremes of destination type.
Simulate Float	None	---
Discrete with status	8-bit Unsigned Integer	Current value converted; no data loss.
	16-bit Unsigned Integer	Current value converted; no data loss.
	32-bit Unsigned Integer	Current value converted; no data loss.
	32-bit Unsigned Integer with status	Current value converted; no data loss.
	Floating Point	Current value converted; no data loss.
	Floating Point with status	Current value converted; no data loss.
	Discrete with status	Bit copy full parameter.
	Boolean	Current value set to zero if source current value equals zero. Else, current value set to one.
	Boolean with status	Current value set to zero if source current value equals zero. Else, current value set to one.
	Option Bitstring	Current value converted; no data loss.
	Named Set	Current value converted; no data loss.
Simulate Discrete	None	---
Option Bitstring	8-bit Unsigned Integer	Current value converted; clamped to extremes of destination type.
	16-bit Unsigned Integer	Current value converted; no data loss.
	32-bit Unsigned Integer	Current value converted; no data loss.
	32-bit Unsigned Integer with status	Current value converted; no data loss.
	Floating Point	Current value converted; no data loss.
	Floating Point with status	Current value converted; no data loss.
	Discrete with status	From 0 to 255, the current value is converted to integer. If the current value becomes greater than 255, the converted value remains at its previous value.
	Boolean	Current value set to zero if source current value equals zero. Else, current value set to one.
	Boolean with status	Current value set to zero if source current value equals zero. Else, current value set to one.
	Option Bitstring	Bit copy full parameter.
	Named Set	Current value converted; clamped to extremes of destination type.
Scaling	Scaling	Bit copy full parameter.
I/O Reference	None	---
Named Set	8-bit Unsigned Integer	Current value converted; no data loss.
	16-bit Unsigned Integer	Current value converted; no data loss.
	32-bit Unsigned Integer	Current value converted; no data loss.
	32-bit Unsigned Integer with status	Current value converted; no data loss.
	Boolean	Current value set to zero if source current value equals zero. Else, current value set to one.
	Floating Point	Current value converted; no data loss.
	Floating Point with status	Current value converted; no data loss.
	Discrete with status	Current value converted; no data loss.
	Boolean with status	Current value set to zero if source current value equals zero. Else, current value set to one.
	Option Bitstring	Current value converted; no data loss.
	Named Set	Bit copy plus pointer duplication. Set strings must match.

Status Handling

The initial status of Logic Solver function block outputs after download is Bad. The way status propagates from input to output makes it possible for Bad status to latch in modules where outputs are wired back to inputs in upstream blocks. If Bad status remains in a module where there are no inputs with Bad status, you may need to re-structure the logic.

Data types that have a status associated with them are treated in one of three ways, depending on the conversion:

When a data type with a status field is converted to another data type with a status field, the status field is copied from one to the other.
When a data type with a status field is converted to a data type without a status field, the status field is lost.
When a data type without a status field is converted to one with a status field, a Good status field is created.

BLOCK_ERR Parameter Bits

Several SIS function blocks have the BLOCK_ERR parameter. The following table shows the BLOCK_ERR bits that can be set in SIS blocks (each block's BLOCK_ERR parameter contains a subset of the bits). The table also shows the bit position for each error and how to access the bits from DeltaV Operate.

Bit Value	Bit Position	Access from DeltaV Operate
Memory Failure	6	BLOCK_ERR.F_CV[7]
Output Failure	7	BLOCK_ERR.F_CV[8]
Input Failure/Bad PV	8	BLOCK_ERR.F_CV[9]
Fault State is Active	10	BLOCK_ERR.F_CV[11]
Simulate Active	12	BLOCK_ERR.F_CV[13]
Configuration Error	14	BLOCK_ERR.F_CV[15]