Process Analog HART (PAH)

The Process Analog HART (PAH) instruction is used to provide HART digital data for an intelligent analog device alongside the analog input (PAI) or analog output (PAO) instruction for that device. It provides:

Available Languages

Ladder Diagram

Function Block Diagram

Structured Text

PAH(PAH_tag, Ref_HARTData, Ref_DiagTable, Ref_UnitsTable)

Configuration Operands

The PAX_HART_DEVICE:I:0 data type is associated with the Add-On Profile for Highly Integrated HART modules such as the 5094-IF8IH.

P_ANALOG_HART Structure

Public members are standard, visible tag members that are programmatically accessible. Private, hidden members are used in HMI faceplates and are not programmatically accessible. Private members are listed in separate tables after public members.

PAX_HART_DEVICE:I:O Structure

The PAX_HART_DEVICE:I:O structure is the input assembly subtype used by Highly-Integrated HART I/O modules to provide all the HART data required for this instruction:

P_HART_CODE_DESC_STATUS Structure

The P_HART_CODE_DESC_STATUS structure is used to look up the diagnostic text and device status associated with a particular Command 48 diagnostic bit. The device provides a 200-bit (25 byte) array of data, where each bit set indicates a particular diagnostic condition. An array of members of this type is used to allow the instruction to display a text description and status for a given bit.

This parameter links the instruction to an external tag that contains necessary data for the instruction to operate. The external tag must be of the data type shown, or may be NULL. If NULL, the diagnostic bit lookup function is not performed.

RAC_CODE_DESCRIPTION[x] Structure

The RAC_CODE_DESCRIPTION[x] structure is an array of engineering unit code numbers and corresponding engineering units text pairs, used as a lookup table. The instruction searches the table for the engineering units code received from the device and displays the corresponding engineering unit text for the variable. This parameter links the instruction to an external tag that contains necessary data for the instruction to operate. The external tag must be of the data type shown, or may be NULL. If NULL, the unit code lookup function is not performed.

Operation

This diagram illustrates functionality of the PAH instruction:

Virtualization

Use virtualization for instruction testing and operator training. Command virtual operation using program command PCmd_Virtual or maintenance command MCmd_Virtual. After finishing virtual operation, use program command PCmd_Physical or maintenance command MCmd_Physical to return to normal physical device operation.

When Virtualization is active, the output dynamic variable (PV, SV, TV, QV) values of the PAH instruction are set using Virtual value settings (Set_VirtualPV, etc.) and I/O faults are ignored. Manipulate the instruction to operate as if a working HART process device were present.

Initialization

The instruction is normally initialized in the instruction first run. Request re-initialization by setting Inp_InitializeReq = 1. For proper initialization, when adding the instruction while performing an online edit of the code, make sure that Inp_InitializeReq = 1, the default value.

Configuration of Strings for HMI

Configure strings for HMI faceplates (FT View) and for the Logix Designer configuration dialog box. The strings are set to extended properties of tag items.

Monitor the PAH Instruction

Use the operator faceplate from the PlantPAx library of Process objects for monitoring.

Affects Math Status Flags

No.

Major/Minor Faults

None specific to this instruction. See Index Through Arrays for array-indexing faults.

Execution

Ladder Diagram

Function Block Diagram

Structured Text

In Structured Text, EnableIn is always true during normal scan. Therefore, if the instruction is in the control path activated by the logic it will execute.

Example

In the following example, the PAH instruction is used alongside a PAI (Process Analog Input) instruction. The PAI provides processing for the analog (4 to 20 mA DC) signal from the HART analog input module, and the PAH instruction provides processing for the digital HART data overlaid upon the analog signal, received from the same field device. As a result, an analog real-time signal is provided for closed-loop control (not shown), and four digital dynamic variables are provided for additional process monitoring.

Ladder Diagram

Function Block Diagram

Structured Text

PAH(TI_301_Dvc, ProMag400_I:I.PAxDevice, HART_DiagTable_Flow, HART_EUTable_Generic);

TI_301.Cfg_InpRawMin:=TI_301_Dvc.Val_InpRawMinFromHART;

TI_301.Cfg_InpRawMax:=TI_301_Dvc.Val_InpRawMaxFromHART;

TI_301.Cfg_PVEUMin:=TI_301_Dvc.Val_PVEUMinFromHART;

TI_301.Cfg_PVEUMax:=TI_301_Dvc.Val_PVEUMaxFromHART;

TI_301.Inp_PVData:=TI_301_Inp_PVData;

TI_301.Inp_ModFault:=TI_301_Inp_ModFault;

TI_301.Inp_ChanFault:=TI_301_Inp_ChanFault;

TI_301.Inp_PVUncertain:=TI_301_Inp_PVUncertain;

PAI(TI_301, 0);