Inovance Function Blocks for HVAC Control: Complete Programming Guide

Learning to implement Function Blocks for HVAC Control using Inovance's InoProShop / AutoShop is an essential skill for PLC programmers working in Building Automation. This comprehensive guide walks you through the fundamentals, providing clear explanations and practical examples that you can apply immediately to real-world projects.

Inovance has established itself as High in China across textiles, packaging, lithium battery, EV manufacturing, elevators, robotics; growing in SE Asia and MEA, making it a strategic choice for HVAC Control applications. With ~2% global, top-3 in China global market share and 7 popular PLC families including the AM600 and AM610, Inovance provides the robust platform needed for intermediate complexity projects like HVAC Control.

The Function Blocks approach is particularly well-suited for HVAC Control because process control, continuous operations, modular programming, and signal flow visualization. This combination allows you to leverage visual representation of signal flow while managing the typical challenges of HVAC Control, including energy optimization and zone control coordination.

Throughout this guide, you'll discover step-by-step implementation strategies, working code examples tested on InoProShop / AutoShop, and industry best practices specific to Building Automation. Whether you're programming your first HVAC Control system or transitioning from another PLC platform, this guide provides the practical knowledge you need to succeed with Inovance Function Blocks programming.

Inovance InoProShop / AutoShop for HVAC Control

Inovance ships InoProShop as its primary programming IDE for the AM600 / AM610 / H5U medium-PLC families and AutoShop for the Easy-series compact PLCs. InoProShop is built on the CODESYS 3.5 platform, which means engineers transferring from Beckhoff TwinCAT, WAGO e!Cockpit, or Schneider EcoStruxure Machine Expert will recognise the project tree, IEC 61131-3 editors, and visualisation tools immediately. AutoShop is a more traditional ladder-and-IL editor closer to compact-PLC tradition. Inovance'...

Platform Strengths for HVAC Control:

CODESYS-based InoProShop for IEC 61131-3 compliance

Tight integration with Inovance servo drives and inverters

Strong motion, robotics, and elevator-control product lines

EtherCAT support across mid-tier and high-end CPUs

Unique ${brand.software} Features:

InoProShop built on CODESYS 3.5 — full IEC 61131-3 compliance

Native EtherCAT motion across mid-tier and high-end CPUs

Tight integration with Inovance servo drives, inverters, and HMIs

AutoShop for compact AC800 / Easy-series CPUs (lighter IDE)

Key Capabilities:

The InoProShop / AutoShop environment excels at HVAC Control applications through its codesys-based inoproshop for iec 61131-3 compliance. This is particularly valuable when working with the 5 sensor types typically found in HVAC Control systems, including Temperature sensors (RTD, Thermocouple), Humidity sensors, Pressure sensors.

Control Equipment for HVAC Control:

Air handling units (AHUs) with supply and return fans

Variable air volume (VAV) boxes with reheat

Chillers and cooling towers for central cooling

Boilers and heat exchangers for heating

Inovance's controller families for HVAC Control include:

AM600: Suitable for intermediate HVAC Control applications

AM610: Suitable for intermediate HVAC Control applications

H5U: Suitable for intermediate HVAC Control applications

AC800: Suitable for intermediate HVAC Control applications

Hardware Selection Guidance:

Inovance CPU choice ranges from Easy320 / Easy510 (compact, AutoShop-programmed, FX-style memory model) through AC800 (mid-range compact) to AM600 / AM610 / H5U (medium PLC with EtherCAT, OPC UA, redundant networking on H5U). AM600 is the volume product for OEM machinery; H5U is the choice for higher-axis-count motion applications and lithium-battery / EV manufacturing lines where EtherCAT and tig...

Industry Recognition:

High in China across textiles, packaging, lithium battery, EV manufacturing, elevators, robotics; growing in SE Asia and MEA. High in Chinese EV manufacturing — Inovance is a major automation supplier to BYD, NIO, and Tier 2/3 EV-component plants. AM600 + H5U with EtherCAT motion controls battery-cell assembly, module welding, pack assembly, and end-of-line test stations. Less common in Western Tier 1 automotive but appear...

Investment Considerations:

With $$ pricing, Inovance positions itself in the mid-range segment. For HVAC Control projects requiring intermediate skill levels and 2-4 weeks development time, the total investment includes hardware, software licensing, training, and ongoing support.

Understanding Function Blocks for HVAC Control

Function Block Diagram (FBD) is a graphical programming language where functions and function blocks are represented as boxes connected by signal lines. Data flows from left to right through the network.

Execution Model:

Blocks execute based on data dependencies - a block executes only when all its inputs are available. Networks execute top to bottom when dependencies allow.

Core Advantages for HVAC Control:

Visual representation of signal flow: Critical for HVAC Control when handling intermediate control logic

Good for modular programming: Critical for HVAC Control when handling intermediate control logic

Reusable components: Critical for HVAC Control when handling intermediate control logic

Excellent for process control: Critical for HVAC Control when handling intermediate control logic

Good for continuous operations: Critical for HVAC Control when handling intermediate control logic

Why Function Blocks Fits HVAC Control:

HVAC Control systems in Building Automation typically involve:

Sensors: Temperature sensors (RTD, thermistors, thermocouples) for zone and supply/return monitoring, Humidity sensors (capacitive or resistive) for moisture control, CO2 sensors for demand-controlled ventilation

Actuators: Variable frequency drives (VFDs) for fan and pump speed control, Modulating control valves (2-way and 3-way) for heating/cooling coils, Damper actuators (0-10V or 4-20mA) for air flow control

Complexity: Intermediate with challenges including Tuning PID loops for slow thermal processes without causing oscillation

Control Strategies for HVAC Control:

zoneTemperature: Cascaded PID control where zone temperature error calculates supply air temperature setpoint, which then modulates cooling/heating valves or VAV damper position

supplyAirTemperature: PID control of cooling coil valve, heating coil valve, or economizer dampers to maintain supply air temperature setpoint

staticPressure: PID control of supply fan VFD speed to maintain duct static pressure setpoint for proper VAV box operation

Programming Fundamentals in Function Blocks:

StandardBlocks:
- logic: AND, OR, XOR, NOT - Boolean logic operations
- comparison: EQ, NE, LT, GT, LE, GE - Compare values
- math: ADD, SUB, MUL, DIV, MOD - Arithmetic operations

TimersCounters:
- ton: Timer On-Delay - Output turns ON after preset time
- tof: Timer Off-Delay - Output turns OFF after preset time
- tp: Pulse Timer - Output pulses for preset time

Connections:
- wires: Connect output pins to input pins to pass data
- branches: One output can connect to multiple inputs
- feedback: Outputs can feed back to inputs for state machines

Best Practices for Function Blocks:

Arrange blocks for clear left-to-right data flow

Use consistent spacing and alignment for readability

Label all inputs and outputs with meaningful names

Create custom FBs for frequently repeated logic patterns

Minimize wire crossings by careful block placement

Common Mistakes to Avoid:

Creating feedback loops without proper initialization

Connecting incompatible data types

Not considering execution order dependencies

Overcrowding networks making them hard to read

Typical Applications:

1. HVAC control: Directly applicable to HVAC Control
2. Temperature control: Related control patterns
3. Flow control: Related control patterns
4. Batch processing: Related control patterns

Understanding these fundamentals prepares you to implement effective Function Blocks solutions for HVAC Control using Inovance InoProShop / AutoShop.

Implementing HVAC Control with Function Blocks

HVAC (Heating, Ventilation, and Air Conditioning) control systems use PLCs to regulate temperature, humidity, and air quality in buildings and industrial facilities. These systems balance comfort, energy efficiency, and equipment longevity through sophisticated control algorithms.

This walkthrough demonstrates practical implementation using Inovance InoProShop / AutoShop and Function Blocks programming.

System Requirements:

A typical HVAC Control implementation includes:

Input Devices (Sensors):
1. Temperature sensors (RTD, thermistors, thermocouples) for zone and supply/return monitoring: Critical for monitoring system state
2. Humidity sensors (capacitive or resistive) for moisture control: Critical for monitoring system state
3. CO2 sensors for demand-controlled ventilation: Critical for monitoring system state
4. Pressure sensors for duct static pressure and building pressurization: Critical for monitoring system state
5. Occupancy sensors (PIR, ultrasonic) for demand-based operation: Critical for monitoring system state

Output Devices (Actuators):
1. Variable frequency drives (VFDs) for fan and pump speed control: Primary control output
2. Modulating control valves (2-way and 3-way) for heating/cooling coils: Supporting control function
3. Damper actuators (0-10V or 4-20mA) for air flow control: Supporting control function
4. Compressor contactors and staging relays: Supporting control function
5. Humidifier and dehumidifier control outputs: Supporting control function

Control Equipment:

Air handling units (AHUs) with supply and return fans

Variable air volume (VAV) boxes with reheat

Chillers and cooling towers for central cooling

Boilers and heat exchangers for heating

Control Strategies for HVAC Control:

zoneTemperature: Cascaded PID control where zone temperature error calculates supply air temperature setpoint, which then modulates cooling/heating valves or VAV damper position

supplyAirTemperature: PID control of cooling coil valve, heating coil valve, or economizer dampers to maintain supply air temperature setpoint

staticPressure: PID control of supply fan VFD speed to maintain duct static pressure setpoint for proper VAV box operation

Implementation Steps:

Step 1: Document all zones with temperature requirements and occupancy schedules

In InoProShop / AutoShop, document all zones with temperature requirements and occupancy schedules.

Step 2: Create I/O list with all sensors, actuators, and their signal types

In InoProShop / AutoShop, create i/o list with all sensors, actuators, and their signal types.

Step 3: Define setpoints, operating limits, and alarm thresholds

In InoProShop / AutoShop, define setpoints, operating limits, and alarm thresholds.

Step 4: Implement zone temperature control loops with anti-windup

In InoProShop / AutoShop, implement zone temperature control loops with anti-windup.

Step 5: Program equipment sequencing with proper lead-lag rotation

In InoProShop / AutoShop, program equipment sequencing with proper lead-lag rotation.

Step 6: Add economizer logic with lockouts for high humidity conditions

In InoProShop / AutoShop, add economizer logic with lockouts for high humidity conditions.

Inovance Function Design:

InoProShop strongly favours function-block reuse via the Library Manager — Inovance ships standard libraries for motion, drives, HMI, OPC UA, and industry-specific applications (lithium-battery, EV, elevator). AutoShop reuse is open-coded via P-label subroutines. OEM machine-builders increasingly default to InoProShop / AM600 to access the FB libraries.

Common Challenges and Solutions:

1. Tuning PID loops for slow thermal processes without causing oscillation

Solution: Function Blocks addresses this through Visual representation of signal flow.

2. Preventing simultaneous heating and cooling which wastes energy

Solution: Function Blocks addresses this through Good for modular programming.

3. Managing zone interactions in open-plan spaces

Solution: Function Blocks addresses this through Reusable components.

4. Balancing fresh air requirements with energy efficiency

Solution: Function Blocks addresses this through Excellent for process control.

Safety Considerations:

Freeze protection for coils with low-limit thermostats and valve positioning

High-limit safety shutoffs for heating equipment

Smoke detector integration for fan shutdown and damper closure

Fire/smoke damper monitoring and control

Emergency ventilation modes for hazardous conditions

Performance Metrics:

Scan Time: Optimize for 5 inputs and 5 outputs

Memory Usage: Efficient data structures for AM600 capabilities

Response Time: Meeting Building Automation requirements for HVAC Control

Inovance Diagnostic Tools:

InoProShop online mode with full POU monitoring and breakpoint debug,EtherCAT diagnostics page with topology and slave status,Trace tool for analogue / motion signal capture,OPC UA server diagnostics page,Modbus communication trace utility,AutoShop online mode for legacy AC800 / Easy series,Inovance HMI integrated diagnostics for HMI-PLC binding faults,Servo-drive panel diagnostics with InoProShop drive-monitor view,EtherCAT slave-firmware update tool,Project compare tool for change tracking

Inovance's InoProShop / AutoShop provides tools for performance monitoring and optimization, essential for achieving the 2-4 weeks development timeline while maintaining code quality.

Inovance Function Blocks Example for HVAC Control

Complete working example demonstrating Function Blocks implementation for HVAC Control using Inovance InoProShop / AutoShop. Follows Inovance naming conventions. Tested on AM600 hardware.

(* Inovance InoProShop / AutoShop - HVAC Control Control *)
(* Reusable Function Blocks Implementation *)
(* InoProShop strongly favours function-block reuse via the Lib *)

FUNCTION_BLOCK FB_HVAC_CONTROL_Controller

VAR_INPUT
    bEnable : BOOL;                  (* Enable control *)
    bReset : BOOL;                   (* Fault reset *)
    rProcessValue : REAL;            (* Temperature sensors (RTD, thermistors, thermocouples) for zone and supply/return monitoring *)
    rSetpoint : REAL := 100.0;  (* Target value *)
    bEmergencyStop : BOOL;           (* Safety input *)
END_VAR

VAR_OUTPUT
    rControlOutput : REAL;           (* Variable frequency drives (VFDs) for fan and pump speed control *)
    bRunning : BOOL;                 (* Process active *)
    bComplete : BOOL;                (* Cycle complete *)
    bFault : BOOL;                   (* Fault status *)
    nFaultCode : INT;                (* Diagnostic code *)
END_VAR

VAR
    (* Internal Function Blocks *)
    fbSafety : FB_SafetyMonitor;     (* Safety logic *)
    fbRamp : FB_RampGenerator;       (* Soft start/stop *)
    fbPID : FB_PIDController;        (* Process control *)
    fbDiag : FB_Diagnostics;         (* InoProShop alarms are typically defined in the visualisation alarm-configuration page with severity, latching, and acknowledgement behaviour configured per alarm. The runtime maintains active and historical alarm lists. AutoShop projects fall back to M-flag banks with HMI-side alarm logging. *)

    (* Internal State *)
    eInternalState : E_ControlState;
    tonWatchdog : TON;
END_VAR

(* Safety Monitor - Freeze protection for coils with low-limit thermostats and valve positioning *)
fbSafety(
    Enable := bEnable,
    EmergencyStop := bEmergencyStop,
    ProcessValue := rProcessValue,
    HighLimit := rSetpoint * 1.2,
    LowLimit := rSetpoint * 0.1
);

(* Main Control Logic *)
IF fbSafety.SafeToRun THEN
    (* Ramp Generator - Prevents startup surge *)
    fbRamp(
        Enable := bEnable,
        TargetValue := rSetpoint,
        RampRate := 20.0,  (* Building Automation rate *)
        CurrentValue => rSetpoint
    );

    (* PID Controller - [object Object] *)
    fbPID(
        Enable := fbRamp.InPosition,
        ProcessValue := rProcessValue,
        Setpoint := fbRamp.CurrentValue,
        Kp := 1.0,
        Ki := 0.1,
        Kd := 0.05,
        OutputMin := 0.0,
        OutputMax := 100.0
    );

    rControlOutput := fbPID.Output;
    bRunning := TRUE;
    bFault := FALSE;
    nFaultCode := 0;

ELSE
    (* Safe State - High-limit safety shutoffs for heating equipment *)
    rControlOutput := 0.0;
    bRunning := FALSE;
    bFault := NOT bEnable;  (* Only fault if not intentional stop *)
    nFaultCode := fbSafety.FaultCode;
END_IF;

(* Diagnostics - InoProShop on AM600 / H5U supports SD-card logging via library FBs, plus OPC UA streaming for cloud / on-premises historians. Inovance HMIs add CSV logging at HMI tier. AutoShop projects rely on HMI-tier logging exclusively. *)
fbDiag(
    ProcessRunning := bRunning,
    FaultActive := bFault,
    ProcessValue := rProcessValue,
    ControlOutput := rControlOutput
);

(* Watchdog - Detects frozen control *)
tonWatchdog(IN := bRunning AND NOT fbPID.OutputChanging, PT := T#10S);
IF tonWatchdog.Q THEN
    bFault := TRUE;
    nFaultCode := 99;  (* Watchdog fault *)
END_IF;

(* Reset Logic *)
IF bReset AND NOT bEmergencyStop THEN
    bFault := FALSE;
    nFaultCode := 0;
    fbDiag.ClearAlarms();
END_IF;

END_FUNCTION_BLOCK

Code Explanation:

1.Encapsulated function block follows InoProShop strongly favours function-blo - reusable across Building Automation projects
2.FB_SafetyMonitor provides Freeze protection for coils with low-limit thermostats and valve positioning including high/low limits
3.FB_RampGenerator prevents startup issues common in HVAC Control systems
4.FB_PIDController tuned for Building Automation: Kp=1.0, Ki=0.1
5.Watchdog timer detects frozen control - critical for intermediate HVAC Control reliability
6.Diagnostic function block enables InoProShop on AM600 / H5U supports SD-card logging via library FBs, plus OPC UA streaming for cloud / on-premises historians. Inovance HMIs add CSV logging at HMI tier. AutoShop projects rely on HMI-tier logging exclusively. and InoProShop alarms are typically defined in the visualisation alarm-configuration page with severity, latching, and acknowledgement behaviour configured per alarm. The runtime maintains active and historical alarm lists. AutoShop projects fall back to M-flag banks with HMI-side alarm logging.

Best Practices

✓Follow Inovance naming conventions: On InoProShop projects, conventions follow CODESYS / IEC norms — PascalCase for
✓Inovance function design: InoProShop strongly favours function-block reuse via the Library Manager — Inova
✓Data organization: InoProShop uses GVLs and persistent variables for shared data. AutoShop uses D /
✓Function Blocks: Arrange blocks for clear left-to-right data flow
✓Function Blocks: Use consistent spacing and alignment for readability
✓Function Blocks: Label all inputs and outputs with meaningful names
✓HVAC Control: Use slow integral action for temperature loops to prevent hunting
✓HVAC Control: Implement anti-windup to prevent integral buildup during saturation
✓HVAC Control: Add rate limiting to outputs to prevent actuator wear
✓Debug with InoProShop / AutoShop: Use InoProShop's online mode to set breakpoints in POUs and step throu
✓Safety: Freeze protection for coils with low-limit thermostats and valve positioning
✓Use InoProShop / AutoShop simulation tools to test HVAC Control logic before deployment

Common Pitfalls to Avoid

⚠Function Blocks: Creating feedback loops without proper initialization
⚠Function Blocks: Connecting incompatible data types
⚠Function Blocks: Not considering execution order dependencies
⚠Inovance common error: EtherCAT slave order mismatch after physical re-cabling — slave addressing break
⚠HVAC Control: Tuning PID loops for slow thermal processes without causing oscillation
⚠HVAC Control: Preventing simultaneous heating and cooling which wastes energy
⚠Neglecting to validate Temperature sensors (RTD, thermistors, thermocouples) for zone and supply/return monitoring leads to control errors
⚠Insufficient comments make Function Blocks programs unmaintainable over time

Related Certifications

🏆Inovance Certified Engineer

🏆InoProShop / AutoShop training certificates

🏆EV / Lithium Battery automation specialist tracks

🏆Advanced Inovance Programming Certification

Mastering Function Blocks for HVAC Control applications using Inovance InoProShop / AutoShop requires understanding both the platform's capabilities and the specific demands of Building Automation. This guide has provided comprehensive coverage of implementation strategies, working code examples, best practices, and common pitfalls to help you succeed with intermediate HVAC Control projects.

Inovance's ~2% global, top-3 in China market share and high in china across textiles, packaging, lithium battery, ev manufacturing, elevators, robotics; growing in se asia and mea demonstrate the platform's capability for demanding applications. The platform excels in Building Automation applications where HVAC Control reliability is critical.

By following the practices outlined in this guide—from proper program structure and Function Blocks best practices to Inovance-specific optimizations—you can deliver reliable HVAC Control systems that meet Building Automation requirements.

Next Steps for Professional Development:

1. Certification: Pursue Inovance Certified Engineer to validate your Inovance expertise
2. Advanced Training: Consider InoProShop / AutoShop training certificates for specialized Building Automation applications
3. Hands-on Practice: Build HVAC Control projects using AM600 hardware
4. Stay Current: Follow InoProShop / AutoShop updates and new Function Blocks features

Function Blocks Foundation:

Function Block Diagram (FBD) is a graphical programming language where functions and function blocks are represented as boxes connected by signal line...

The 2-4 weeks typical timeline for HVAC Control projects will decrease as you gain experience with these patterns and techniques. Remember: Use slow integral action for temperature loops to prevent hunting

For further learning, explore related topics including Temperature control, Hospital environmental systems, and Inovance platform-specific features for HVAC Control optimization.