Edge Server Data Processors

The ControlCom Edge Server provides three powerful features for processing and automating data at the edge: Value Transforms, Virtual Variables, and Triggers. These features allow you to modify, compute, and act on device data before it reaches the platform.

Prerequisites

This guide requires the ControlCom Edge Server to be onboarded and configured with at least one device. See our Onboarding Guide for the Edge Server and Reading Modbus Data guides to get started.

Value Transforms

Value Transforms modify the read value from a device item before it is sent to the platform. They allow you to apply calculations, conversions, or transformations to raw device data.

Key Features

• Multiple transforms can be chained on a single item (executed in rank order 1-999)
• Each transform receives the output of the previous transform as its input
• Uses a special {{READ_VALUE}} variable that references the current value in the chain
• Supports complex expressions including unit conversions, thresholds, and formulas

Navigation

Path: Configuration > Devices > [Select Device] > SDK Tab > [Select Modbus Client] > [Select Modbus Item] > Transforms Tab

Creating a Value Transform

1. Navigate to a Modbus Item's Transforms tab
2. Click "+ Add Transform"
3. Fill in the required fields:

Example Expressions

// Unit conversion (pounds to kilograms)
{{READ_VALUE}} * 0.453592

// Threshold to boolean
{{READ_VALUE}} > 100 ? 1 : 0

// Using device variables
{{READ_VALUE}} * {{calibration_factor}} / 100

Real-World Use Cases

Temperature Sensor Calibration Raw sensor reads 23.5°C but needs +0.8°C offset:

{{READ_VALUE}} + 0.8

Pressure Unit Conversion (PSI to Bar) Device reports in PSI, platform needs Bar:

{{READ_VALUE}} * 0.0689476

Flow Rate Scaling Raw value is 0-4095 (12-bit ADC), actual flow is 0-500 GPM:

{{READ_VALUE}} / 4095 * 500

Boolean Status from Analog Value Motor running if current > 2 amps:

{{READ_VALUE}} > 2 ? 1 : 0

Multi-Step Transform Chain

• Rank 1: Apply calibration offset: {{READ_VALUE}} + 1.5
• Rank 2: Convert units: {{READ_VALUE}} * 0.0689476
• Rank 3: Round to 2 decimals: Math.round({{READ_VALUE}} * 100) / 100

Virtual Variables

Virtual Variables are computed values created from device variables using expressions. They enable Edge Servers to create NEW custom data points that are published to a specified topic property path. Unlike Value Transforms (which modify existing values), Virtual Variables create entirely new computed values.

Key Features

• Create complex expressions using multiple device variables
• Support multiple data types (NUMBER, BOOLEAN, STRING)
• Published to a new topic property path (creates new data points)
• Can be enabled/disabled without deletion
• Independent of specific Modbus items (uses any device variables)

Navigation

Path: Configuration > Devices > [Select Device] > SDK Tab > Virtual Variables Tab (green Calculator icon)

Creating a Virtual Variable

1. Navigate to the device's SDK tab
2. Click the Virtual Variables tab
3. Click "Add Virtual Variable" or the "+" card
4. Fill in the required fields:

Variable Syntax

Reference device variables using double braces: {{variableName}}

Example Expressions

// Average of two temperature sensors
({{temperature_sensor_1}} + {{temperature_sensor_2}}) / 2

// Power calculation
{{voltage}} * {{current}}

// Conditional logic
({{temperature}} > 25) ? {{fan_control}} : 0

Real-World Use Cases

Average Temperature Calculation Combine multiple temperature sensors into one reading:

• Topic Property Path: temperature/average
• Expression: ({{zone1_temp}} + {{zone2_temp}} + {{zone3_temp}}) / 3

Power Consumption (kW) Calculate real power from voltage and current:

• Topic Property Path: power/consumption_kw
• Expression: {{voltage}} * {{current}} / 1000

Efficiency Percentage Calculate equipment efficiency from input/output:

• Topic Property Path: efficiency/percentage
• Expression: ({{output_power}} / {{input_power}}) * 100

Delta Temperature Calculate temperature difference between supply and return:

• Topic Property Path: temperature/delta
• Expression: {{supply_temp}} - {{return_temp}}

Runtime Hours Estimation Convert seconds counter to hours:

• Topic Property Path: runtime/hours
• Expression: {{runtime_seconds}} / 3600

Conditional Fan Control Enable fan output based on temperature threshold:

• Topic Property Path: controls/fan_enable
• Expression: ({{temperature}} > 30) ? 1 : 0

Triggers

Triggers are automation features that evaluate a boolean expression and execute a command when a specific condition transitions from FALSE to TRUE. They enable edge server automation based on device variable states.

Key Features

• Edge-triggered: Execute when condition changes from FALSE to TRUE (not continuously)
• Command execution: Write a configurable value to a specified command/write variable
• Optional re-execution: Can repeatedly execute at specified intervals while condition remains TRUE
• Two-state actions: Can write different values when condition becomes TRUE vs FALSE

Navigation

Path: Administration > Devices > [Select Device] > Edge Server tab > Triggers tab

Creating a Trigger

1. Navigate to a device's Edge Server tab
2. Click the Triggers tab
3. Click "Add Trigger"
4. Fill in the required fields:

Example Trigger Configuration

• Name: "High Temperature Alert"
• Condition: {{temperature}} > 100
• Write Variable: alarm_output
• Value on True: 1
• Value on False: 0
• Re-execute Interval: (empty for single execution)

Real-World Use Cases

High Temperature Alarm Activate alarm when temperature exceeds safe limit:

• Condition: {{temperature}} > 85
• Write Variable: alarm_relay
• Value on True: 1 | Value on False: 0

Low Tank Level Alert Start fill pump when tank drops below 20%:

• Condition: {{tank_level}} < 20
• Write Variable: fill_pump_start
• Value on True: 1 | Value on False: 0

Equipment Fault Response Stop equipment when fault is detected:

• Condition: {{fault_code}} != 0
• Write Variable: emergency_stop
• Value on True: 1

Periodic Heartbeat Send keepalive signal every 5 seconds while system is running:

• Condition: {{system_running}} == 1
• Write Variable: heartbeat_output
• Value on True: 1
• Re-execute Interval: 5000 (5 seconds)

Pressure Safety Shutdown Emergency shutdown if pressure exceeds critical threshold:

• Condition: {{pressure}} > 150 || {{pressure}} < 10
• Write Variable: safety_shutdown
• Value on True: 1

Motor Overload Protection Stop motor if current draw exceeds rating:

• Condition: {{motor_current}} > {{motor_rated_current}} * 1.2
• Write Variable: motor_stop_command
• Value on True: 1 | Value on False: 0

Summary

Feature Comparison

Key Differences

Access Requirements

All three features are accessible within the device SDK configuration tab after the Edge Server has been onboarded and configured.