MV_SPLIT (Split Range Controller) Logic Block Documentation

Overview

The MV_SPLIT block is an essential control module in process automation systems designed to implement split-range control. It allows a single manipulated variable (MV)—typically from a PID or control logic—to be distributed across two separate actuators (e.g., control valves or dampers) based on predefined ranges.

This logic is commonly used in: - Temperature control (heating/cooling valves) - Flow control (dual parallel valves) - Pressure control systems

By managing how each actuator responds to different ranges of the MV, the block ensures: - Smooth transitions - Optimized actuator usage - Improved loop stability

---

Logic Block Illustration

The MV_SPLIT logic block is used to control and monitor a split-range control valve, typically used in analog control loops. It divides the input signal to operate two actuators or two ranges of a single actuator, allowing fine-grained control over a wider operational range.

A visual representation of the MV_SPLIT block, showing its function in distributing a single control signal into two separate actuator signals, depending on the configured range.

The above pictures show how the inputs and outputs are connected in the MV_SPLIT block.

This illustration shows the correct signal mapping and usage of the MV_SPLIT block within a process automation program, including control signal ranges and output behavior for dual-valve control.

---

Functional Description

• In Auto Mode, the block uses the Input MV signal and calculates the outputs based on:
• Defined limits (MinLimit1, MaxLimit1, etc.)

• Ratios and biases (Ratio1, Bias1, etc.)

• In Manual Mode, users can directly set outputs using:

• ManOutput1 and ManOutput2

This allows for both automated split control and manual override during commissioning or testing.

---

Input and Output Parameters

Signal	Type	Description
Input	REAL	Main manipulated variable (MV) typically from PID
AutoMode	BOOL	Mode selection: TRUE = Auto, FALSE = Manual
ManOutput1	REAL	Manual override value for Output1
ManOutput2	REAL	Manual override value for Output2
Ratio1	REAL	Scaling ratio for Output1
Ratio2	REAL	Scaling ratio for Output2
Bias1	REAL	Bias (offset) for Output1
Bias2	REAL	Bias (offset) for Output2
MinLimit1	REAL	Minimum clamp for Output1
MaxLimit1	REAL	Maximum clamp for Output1
MinLimit2	REAL	Minimum clamp for Output2
MaxLimit2	REAL	Maximum clamp for Output2
Output1	REAL	Final calculated Output1 value
Output2	REAL	Final calculated Output2 value

---

Operational Logic

🔄 Auto Mode (AutoMode = TRUE)

• Output values are automatically calculated based on the live Input, adjusted by Ratio and Bias, and bounded within defined Min and Max limits.

🔧 Manual Mode (AutoMode = FALSE)

• Allows the operator to directly assign values to ManOutput1 and ManOutput2.
• Useful in the following cases:
  • 🔧 Plant commissioning and tuning
  • 🚨 Manual override during fault or abnormal conditions
  • 🔄 Temporary bypass of automation logic
• Outputs are still clamped between the configured limits to ensure safety and consistency.

---

Training Demo Video

Demonstration video is available , How to use the MOV_INCHING Logic Block through Library:

MV-Split Block Demo - TPW Logic Setup

---

Use Case Scenario

💡 Example 1: Valve Split Control

• Valve 1: operates from 0%–50% MV
• Valve 2: operates from 50%–100% MV

```text Ratio1 = 1.0, Bias1 = 0, MinLimit1 = 0, MaxLimit1 = 50
Ratio2 = 1.0, Bias2 = -50, MinLimit2 = 0, MaxLimit2 = 50