PlantPAx 4.x Library of Process Objects: Complete AOI Reference Guide
The PlantPAx Library of Process Objects is the foundation of every PlantPAx DCS project. It provides a standardized set of Add-On Instructions (AOIs) for I/O conditioning, regulatory control, motor management, valve control, interlocks, permissives, and alarm handling — all built to ISA-18.2 alarm standards with matching FactoryTalk View SE/ME faceplates. This guide catalogs every AOI in the PlantPAx 4.x library (v4.10.06), organized by category, so you can quickly identify which objects your project needs. Whether you are specifying a new PlantPAx system, evaluating the platform against other DCS solutions, or onboarding engineers to an existing installation, this reference gives you a complete picture of the library’s capabilities.
Contents
1. What Is the PlantPAx Library of Process Objects?
The PlantPAx Library of Process Objects is a downloadable collection of pre-built Add-On Instructions (AOIs), HMI faceplates, global objects, and documentation that ships with every PlantPAx DCS project. It is available from the Rockwell Automation Product Compatibility and Download Center (PCDC) and installs directly into Studio 5000 Logix Designer.
The current version is 4.10.06 (April 2023), part of the PlantPAx 4.x platform. The library contains approximately 45+ process objects spanning five categories: I/O processing, regulatory and procedural control, motors, valves, and cross-functional objects. Each object includes controller logic (AOI), one or more HMI faceplates (Faceplate, Help, Quick View), and global object symbols for FactoryTalk View.
What the Library Includes
| Component | Description |
|---|---|
| Add-On Instructions (AOIs) | Pre-built controller logic blocks for each process object — drag into your Logix project |
| HMI Faceplates | FactoryTalk View SE/ME display screens for each object (Faceplate, Help, Quick View) |
| Global Objects | Reusable HMI graphic symbols for P&ID-style process displays |
| Online Configuration Tool | Spreadsheet-based tool for bulk online parameter changes across all objects |
| Documentation | Three companion manuals covering configuration, logic reference, and HMI reference |
Companion Documentation
| Publication | Title | Covers |
|---|---|---|
| PROCES-RM002 | Library of Process Objects: Configuration and Usage | Installation, command source model, alarm model, simulation, HMI faceplates, online configuration |
| PROCES-RM013 | Library of Process Objects: Logic Instructions | Detailed AOI reference — every parameter, every InOut tag, every status bit for all 45+ objects |
| PROCES-RM014 | Library of Process Objects: HMI Elements | Faceplate configuration, global object setup, display navigation, alarm summary |
Download from PCDC
The PlantPAx Library of Process Objects is a free download from the Rockwell Automation Product Compatibility and Download Center (PCDC). Search for “PlantPAx Library” and select the version matching your Studio 5000 release. The library requires Studio 5000 Logix Designer v32 or later.
2. I/O Processing Objects
I/O processing objects handle the interface between physical field instruments and the control strategy. They provide scaling, alarm detection, signal conditioning, simulation, and channel-level diagnostics. Every analog or discrete signal entering or leaving the controller passes through one of these objects.
| AOI | Name | Description | When to Use |
|---|---|---|---|
| P_AIn | Analog Input | Basic analog input with scaling, Hi/Lo/HiHi/LoLo alarms, and substitute PV | Temperature, flow, pressure, or level from a single field instrument |
| P_AIChan | Analog Input Channel | Maps raw I/O module channel data to a P_AIn object | When you want channel-level configuration separate from the analog input object |
| P_AInAdv | Advanced Analog Input | Adds square root extraction, rate-of-change alarming, and deviation alarming from a reference value | Orifice plate flowmeters or signals needing advanced conditioning |
| P_AInDual | Dual Sensor Analog Input | Two sensors for one process variable — select primary, secondary, or average | Redundant pH probes, dual temperature sensors |
| P_AInMulti | Multiple Analog Input | More than two sensors with average or median selection | Triple-redundant or voting sensor configurations |
| P_AInHART | HART Analog Input | Analog input with HART diagnostic passthrough | HART-enabled transmitters on 1756-IF4IH modules |
| P_DIn | Discrete Input | Single discrete (digital) input with on/off delay timers and alarm capability | Limit switches, pressure switches, level switches |
| P_DInAdv | Discrete Input Advanced | Adds additional alarm points and diagnostic features beyond P_DIn | Discrete inputs requiring extended alarm or diagnostic coverage |
| P_AOut | Analog Output | Single analog output with scaling, tracking, and alarm | Control valve positioners, VFD speed references via analog signal |
| P_AOutHART | HART Analog Output | Analog output with HART diagnostic passthrough | HART-enabled positioners or actuators |
| P_DOut | Discrete Output | Single discrete output with command source, alarm, and simulation | Solenoids, indicator lights, simple on/off devices |
| P_PTComp | Pressure/Temperature Compensated Flow | Calculates compensated flow from raw flow, pressure, and temperature inputs | Gas flow measurement requiring P/T compensation |
| P_StrapTbl | Tank Strapping Table | Converts level measurement to volume using a linearization table | Irregularly shaped tanks where level ≠ volume |
Start with P_AIn and P_DIn
For most projects, P_AIn and P_DIn are the workhorses. Use the advanced variants only when you need specific features like dual-sensor voting (P_AInDual), square root extraction (P_AInAdv), or HART diagnostics (P_AInHART). Over-specifying I/O objects adds unnecessary controller memory consumption.
3. Regulatory and Procedural Control Objects
Regulatory control objects implement closed-loop and procedural control strategies. The centerpiece is P_PIDE — a full-featured PID controller with autotune, cascade, and feedforward capability. The remaining objects in this category handle output splitting, signal selection, on/off deadband control, sequencing, dosing, and motor group management.
| AOI | Name | Description | When to Use |
|---|---|---|---|
| P_PIDE | PID Enhanced | Full-featured PID with autotune, anti-windup, feedforward, cascade, output tracking, and bumpless transfer | Every PID loop — the primary regulatory control object in the library |
| P_Fanout | Analog Fanout | Splits one analog output to drive multiple downstream objects | Split-range valve control (e.g., one controller drives heating and cooling valves) |
| P_HiLoSel | High or Low Selector | Selects the highest or lowest of multiple analog inputs | Override control (e.g., select highest of 3 temperatures for safety trip) |
| P_DBC | Deadband Controller | On/off controller with configurable deadband | Simple level control (fill when low, stop when high) or temperature control without PID |
| P_Seq | Sequencer | Step sequence with transitions, timers, actions, and operator prompts | Simple sequential operations — startup sequences, CIP wash cycles |
| P_Dose | Dosing | Controls a dosing/batching operation — open valve, measure quantity, close when target reached | Ingredient addition in batch processes |
| P_LLS | Lead/Lag/Standby Motor Group | Manages a group of motors in lead/lag/standby rotation with automatic failover | Pump stations, cooling tower fan groups, redundant compressors |
P_PIDE Is the Workhorse
The P_PIDE object is the single most important AOI in the PlantPAx library. It handles 90%+ of regulatory control needs. Its autotune feature uses internal model control (IMC) tuning to calculate P, I, and D gains automatically — connect it to a P_AIn for PV and a P_AOut or P_ValveC for CV, and run autotune.
4. Motor Control Objects
Motor control objects cover everything from basic across-the-line starters to network-connected variable frequency drives. The library includes dedicated AOIs for specific Allen-Bradley drive families (PowerFlex, SMC) as well as a generic VSD object for hardwired drives. Supporting objects track runtime hours, start counts, and restart inhibit timers for maintenance scheduling.
Basic Motor Objects
| AOI | Name | Description | When to Use |
|---|---|---|---|
| P_Motor | Single-speed Motor | Start/stop with interlocks, permissives, runtime tracking, and alarm | Standard across-the-line motor starters — the default motor object |
| P_Motor2Spd | Two-speed Motor | Motor with high/low speed selection | Two-winding motors with discrete speed steps |
| P_MotorRev | Reversing Motor | Motor with forward/reverse capability | Conveyors, mixers, or devices requiring directional control |
| P_MotorHO | Hand-operated Motor | Manually operated motor (local panel only, no PLC control) with run feedback monitoring | Motors controlled from a local panel — monitoring and alarm/runtime tracking only |
PowerFlex Drive Objects
| AOI | Name | Description | When to Use |
|---|---|---|---|
| P_PF52x | PowerFlex 523/525 | Dedicated AOI for PF523/525 VFDs via EtherNet/IP with speed reference, start/stop, fault diagnostics, and InOut structure mapping | PowerFlex 523 or 525 drives connected over EtherNet/IP |
| P_PF753 | PowerFlex 753 | Dedicated AOI for PowerFlex 753 VFDs | PowerFlex 753 drives on EtherNet/IP |
| P_PF755 | PowerFlex 755/755TL/TR | Dedicated AOI for the PowerFlex 755 family | PowerFlex 755, 755TL, or 755TR drives on EtherNet/IP |
| P_PF6000 | PowerFlex 6000 | Medium-voltage drive control object | PowerFlex 6000 medium-voltage drives |
| P_PF7000 | PowerFlex 7000 | Medium-voltage drive control object | PowerFlex 7000 medium-voltage drives |
Soft Starters and Generic VSD
| AOI | Name | Description | When to Use |
|---|---|---|---|
| P_SMC50 | SMC-50 Smart Motor Controller | Soft starter control with EtherNet/IP integration | SMC-50 soft starters on EtherNet/IP |
| P_SMCFlex | SMC Flex Smart Motor Controller | Soft starter control for SMC Flex devices | SMC Flex soft starters on EtherNet/IP |
| P_VSD | Variable-speed Drive (Generic) | Generic VFD object for hardwired drives (analog output + discrete I/O) | Any VFD controlled via 4–20 mA speed reference rather than network integration |
Overload Relays and Utilities
| AOI | Name | Description | When to Use |
|---|---|---|---|
| P_E1PlusE | E1 Plus Overload Relay | Monitors E1 Plus electronic overload relay status | E1 Plus overload relays |
| P_E3Ovld | E3/E3Plus Overload Relay | Monitors E3 series overload relay via EtherNet/IP | E3 or E3 Plus overload relays on EtherNet/IP |
| P_E300Ovld | E300 Overload Relay | Monitors E300 electronic overload relay via EtherNet/IP | E300 overload relays on EtherNet/IP |
| P_RunTime | Runtime and Start Counter | Tracks cumulative runtime hours and start count for maintenance scheduling | Any motor or rotating device requiring maintenance tracking |
| P_ResInh | Restart Inhibit | Prevents rapid restart of large motors (thermal protection) with configurable inhibit time | Large motors requiring cool-down time between restarts |
5. Valve Control Objects
Valve objects cover the full spectrum of process valves — from simple solenoid on/off valves to modulating control valves and hygienic mix-proof valves for food/beverage and pharmaceutical applications. Each valve object includes position feedback monitoring, alarm capability, command source management, and simulation mode.
| AOI | Name | Description | When to Use |
|---|---|---|---|
| P_ValveSO | Solenoid-operated Valve | Simple on/off solenoid valve with open/close feedback, alarm, and command source | The most common valve object — solenoid valves, pneumatic on/off valves |
| P_ValveC | Analog/Pulsed Control Valve | Modulating control valve with analog position output | Globe valves, butterfly valves controlled by 4–20 mA positioners |
| P_ValveMO | Motor-operated Valve | Valve driven by an electric motor actuator (open/close commands) | Gate valves, ball valves with MOV actuators |
| P_ValveHO | Hand-operated Valve | Manually operated valve — no PLC control, monitors position feedback | Manual valves where position status and alarm/tracking are needed |
| P_ValveMP | Mix-proof Valve | Hygienic mix-proof (double-seat) valve with two independent valve seats and leak detection | Food & beverage, pharmaceutical — hygienic piping with product separation |
| P_ValveMPAdv | Advanced Mix-proof Valve | Extended mix-proof valve with additional diagnostics and seat lift features | Complex hygienic applications requiring advanced seat lift and diagnostic capability |
| P_ValveStats | 2-state Valve Statistics | Tracks valve cycle count and cumulative open time for maintenance | Any on/off valve requiring cycle counting for predictive maintenance |
| P_nPos | n-Position Device | Device with n discrete positions (2, 3, or more) | Multi-port valves, diverters, selector switches, any multi-position actuator |
P_ValveSO for Most On/Off Valves
P_ValveSO is the default choice for any on/off valve — solenoid, pneumatic, or air-operated. Use P_ValveC only for modulating (throttling) valves with analog positioners. Use P_ValveMO only for motor-operated valves with discrete open/close actuator commands.
6. Cross Functional Objects
Cross-functional objects provide the “glue” that ties a PlantPAx system together — interlocks, permissives, alarms, command source management, operator prompts, and generic multi-state devices. The most widely used objects in this category are P_Intlk (interlocks), P_Perm (permissives), P_Alarm (standalone alarms), and P_CmdSrc (command source management).
| AOI | Name | Description | When to Use |
|---|---|---|---|
| P_Intlk | Interlocks with First Out and Bypass | Up to 16 interlock inputs with first-out indication and individual bypass capability | The standard interlock object — trip conditions that shut down equipment |
| P_IntlkAdv | Advanced Interlocks | Extended version with additional interlock inputs and advanced features | Applications requiring more than 16 interlock inputs per device |
| P_Perm | Permissives with Bypass | Up to 16 permissive inputs, each individually bypassable | Startup permissive checks — conditions that must be true before equipment can start |
| P_Gate | Condition Gate Delay | Configurable on-delay and off-delay for any Boolean condition | Debouncing signals, time-delayed interlocks, conditional timers |
| P_D4SD | Discrete 2/3/4-state Device | Generic device with 2, 3, or 4 discrete states | Multi-position devices not covered by specific valve or motor objects |
| P_Alarm | Common Alarm Block | Standalone alarm with ISA-18.2 alarm state model (Active/Acknowledged/Suppressed/Shelved) | Custom alarms not tied to a specific device object |
| P_CmdSrc | Command Source | Manages command source priority: Program, Operator, External, Override, Maintenance | Standalone use — also embedded in every motor and valve object |
| P_Reset | Central Reset | Resets all alarms and faults across multiple objects with a single command | Area-wide or unit-wide reset buttons on operator displays |
| P_Prompt | Operator Prompt | Displays a prompt on the HMI requesting operator action or confirmation | Manual steps within sequences — “confirm valve is open” type interactions |
| P_Logic | Boolean Logic with Snapshot | Captures and displays Boolean logic state for troubleshooting | Making complex interlock logic visible to operators for diagnostics |
Interlocks vs Permissives
Interlocks (P_Intlk) are trip conditions — they shut down running equipment when a dangerous condition occurs. Permissives (P_Perm) are start conditions — they prevent equipment from starting until all prerequisites are met. Both support individual input bypass for maintenance, but they serve fundamentally different roles in the safety and control strategy.
7. Common Features Across All Objects
Every process object in the PlantPAx library shares a common set of features that provide consistency across the entire DCS. These features are documented in detail in PROCES-RM002 (Configuration and Usage).
Command Source Model
Every device object (motor, valve, drive) supports five command sources with configurable priority:
| Source | Priority | Typical Use |
|---|---|---|
| Override | Highest | Safety or emergency actions that take precedence over everything |
| Maintenance | High | Maintenance technicians testing or servicing equipment |
| External | Medium | Higher-level control (batch sequencer, MES, optimization layer) |
| Program | Normal | Continuous control logic running in the controller |
| Operator | Normal | Manual operator commands from the HMI faceplate |
ISA-18.2 Alarm State Model
All alarm-capable objects follow the ISA-18.2 standard alarm state model. Each alarm point can be in one of four states:
| State | Description |
|---|---|
| Active / Unacknowledged | Alarm condition is present and has not been acknowledged by an operator |
| Active / Acknowledged | Alarm condition is present and has been acknowledged |
| Clear / Unacknowledged | Alarm condition has cleared but the operator has not yet acknowledged it (return-to-normal) |
| Suppressed | Alarm is temporarily hidden from the operator (e.g., during maintenance or startup) |
| Shelved | Alarm is removed from active display for a defined time period (ISA-18.2 shelving) |
| Out of Service | Alarm is disabled — will not annunciate regardless of process condition |
Additional Common Features
| Feature | Description |
|---|---|
| Simulation Mode | Every I/O object supports simulation for testing without physical I/O connected — substitute values can be set from the HMI faceplate |
| HMI Faceplates | Each object has matching FactoryTalk View SE/ME faceplates: Faceplate (full control), Help (documentation), Quick View (status at a glance) |
| Global Objects | Reusable HMI graphic symbols for each object type — drag onto P&ID-style process displays |
| Online Configuration | Parameters can be changed online via the PlantPAx Online Configuration Tool — a spreadsheet-based utility that reads/writes object parameters in bulk |
| Consistent Naming | All objects use the P_ prefix (P_AIn, P_Motor, P_ValveSO) for easy identification in the Studio 5000 project tree |
8. Related Guides
These PLC Exchange guides cover specific hardware and applications referenced throughout this process objects overview:
| Guide | Description |
|---|---|
| 1756-L85E ControlLogix 5580 for PlantPAx | Controller selection, PlantPAx architecture planning, system sizing, and redundancy configuration for the top-of-line ControlLogix 5580 |
| 1756-L83E ControlLogix 5580 Guide | Installation, wiring, configuration, and programming for the mid-range ControlLogix 5580 controller |
| CompactLogix 5069 E-Stop Safety Circuit | Safety-rated E-Stop circuit design using GuardLogix safety controllers and POINT I/O safety modules |
Building a PlantPAx System?
If you are specifying ControlLogix hardware for a PlantPAx project, start with our 1756-L85E PlantPAx guide for controller sizing and architecture guidance, then use this process objects reference to plan your AOI library.
Reference Documentation
The following Rockwell Automation publications were used as references for this guide. These are the official manufacturer documents for the hardware covered in this article.
| Publication | Description | Download |
|---|---|---|
| PROCES-RM013 | Library of Process Objects: Logic Instructions (v4.10) | |
| PROCES-RM002 | Library of Process Objects: Configuration and Usage (v4.0) | |
| PROCES-RM001 | PlantPAx Distributed Control System Reference Manual |
Need ControlLogix Hardware for Your PlantPAx System?
PLC Exchange stocks ControlLogix 5580 controllers, chassis, power supplies, communication modules, and I/O for PlantPAx systems. 2.5-year warranty and same-day shipping.