Industrial Standard Protocol

Modbus: The Universal Equipment Translator

When equipment needs to talk to your BMS, Modbus is often the common language. Simple, reliable, and everywhere — if you know how to speak it.

Discuss Modbus Integration

What is Modbus?

Modbus is an industrial communication protocol developed by Modicon in 1979. It's one of the oldest and most widely used protocols for connecting electronic devices.

In building automation, Modbus is the lingua franca for equipment. Chillers, boilers, VFDs, generators, electrical meters, water meters — if it has a communications port, it probably speaks Modbus.

The protocol is simple by design: read registers, write registers. No complex object models or service discovery. This simplicity is both its strength and its limitation.

Modbus RTU

Serial communication over RS-485 or RS-232. Common for field devices. Binary format for efficiency.

Modbus TCP

Modbus over Ethernet/IP. Same register model, network transport. Modern equipment preference.

Modbus ASCII

Human-readable format over serial. Less common but still encountered in legacy systems.

Common Modbus Integration Scenarios

Modbus shows up everywhere in building systems. Here's where we use it most.

Chillers & Boilers

Central plant equipment almost always has Modbus. We integrate chillers, boilers, and cooling towers with your BMS for full visibility and control.

VFDs & Motor Controllers

Variable frequency drives communicate speed, current, faults, and commands via Modbus. Essential for energy monitoring and optimization.

Electrical Meters

Power meters, submeters, and energy monitoring devices. Critical for energy management and LL97/LL84 compliance in NYC.

Generators & UPS

Backup power systems report status, runtime, fuel levels, and alarms via Modbus. Integration provides visibility into critical systems.

Water & Gas Meters

Utility submetering for tenant billing, leak detection, and consumption tracking. Modbus is the standard interface.

Specialty Equipment

Lab equipment, process systems, refrigeration, kitchen exhaust — if it has a Modbus port, we can integrate it.

The Register Map Challenge

Modbus is simple in concept but complex in practice. Every device has its own register map — the list of addresses where data lives and what format it's in.

Getting Modbus integration right requires:

  • Register map documentation from the manufacturer
  • Data type understanding (16-bit, 32-bit, float, scaled integers)
  • Byte order awareness (big-endian vs. little-endian)
  • Scaling factors for engineering units
  • Polling strategy for performance

What We Deliver

We don't just connect the wires. We deliver working integrations:

  • →
    Proper point mapping

    Every register mapped to meaningful BMS points

  • →
    Correct scaling

    Values display in proper engineering units

  • →
    Alarm mapping

    Equipment faults surface in your BMS

  • →
    Command integration

    Control equipment from your BMS when appropriate

Our Modbus Integration Process

1

Documentation Review

Obtain register maps from equipment manufacturers. Identify the points that matter for your operation.

2

Communication Setup

Configure serial or network connections. Verify device addresses and communication parameters.

3

Point Configuration

Build the integration in Niagara or your BMS. Map registers to points with proper scaling and naming.

4

Verification

Compare BMS values to equipment displays. Test commands. Verify alarm propagation.

5

Graphics & Trending

Build equipment graphics. Set up historical trending for the data that matters.

6

Documentation

Deliver complete documentation: point lists, register maps, communication settings, graphics.

Equipment That Needs Integrating?

Whether it's a new chiller, existing meters, or a building full of equipment — we can connect it to your BMS.

Discuss Your Integration