Features

Dual Protocol Support

ModbusBB supports both major Modbus protocols, giving you complete flexibility for any industrial application.

Modbus TCP/IP - Connect to devices over Ethernet networks with configurable IP address and port
Modbus RTU - Serial communication with full configuration for baud rate, parity, data bits, and stop bits
Auto-reconnect - Automatic reconnection on connection loss
Multiple connections - Connect to multiple devices simultaneously

TCP Settings

IP: 192.168.1.100

Port: 502

RTU Settings

COM3 @ 9600 baud

8N1 (8 data, No parity, 1 stop)

Complete Function Code Support

Access all standard Modbus function codes for reading and writing data to your devices.

FC 01 Read Coils

FC 02 Read Discrete Inputs

FC 03 Read Holding Registers

FC 04 Read Input Registers

FC 05 Write Single Coil

FC 06 Write Single Register

FC 15 Write Multiple Coils

FC 16 Write Multiple Registers

Multiple Data Formats

View and edit register data in the format that makes sense for your application. Set format per-address for mixed data types.

Binary - Perfect for coil and discrete input visualization
Unsigned Integer - Standard 16-bit unsigned values (0-65535)
Signed Integer - 16-bit signed values (-32768 to 32767)
Hexadecimal - Raw hex values for protocol debugging
Float32 (IEEE 754) - 32-bit floating point using 2 registers
Int32 / UInt32 - 32-bit signed/unsigned integer values using 2 registers
Per-Address Format - Set different formats for each register independently

Binary: 1010 0011 0111 1001

Decimal: 41849

Hex: 0xA379

Float32: 123.456

Flexible Byte Order

Handle 32-bit values from any device with full byte order support for multi-register data types.

ABCD (Big Endian) - Most significant byte first, standard for many PLCs
DCBA (Little Endian) - Least significant byte first
BADC (Byte Swap) - Big endian with bytes swapped within words
CDAB (Word Swap) - Words swapped, common in Siemens devices
Per-Address Setting - Set byte order independently for each register

ABCD: 0x12345678

DCBA: 0x78563412

BADC: 0x34127856

CDAB: 0x56781234

Auto Polling

Monitor your Modbus devices in real-time with configurable automatic polling.

Configurable intervals - From 100ms to 10 seconds
Start/Stop control - Easy polling control with single click
Real-time updates - Watch values change as they happen
Error handling - Automatic retry on communication failures

Communication Logging

Full visibility into all Modbus communication for debugging and analysis.

Request/Response logging - See every message sent and received
Timestamp tracking - Know exactly when each transaction occurred
Response time display - See TX/RX timing in milliseconds
Error logging - Capture and diagnose communication errors
Export to file - Save logs for later analysis or reporting
Clear/Filter - Manage log entries easily

[10:23:45] TX: 01 03 00 00 00 0A

[10:23:45] RX: 01 03 14 00 64... (12ms)

[10:23:46] TX: 01 03 00 00 00 0A

[10:23:47] ERR: Timeout

Register Aliases & Configuration

Organize your workspace with human-readable names and save your setup for later.

Register Aliases - Name registers like "Temperature Sensor 1" instead of just address numbers
Import/Export Config - Save connection settings, aliases, and formats to file
Hex Address Support - Enter addresses in hex (0x0190) for OEM documentation compatibility
Response Time Display - See TX/RX timing in milliseconds for performance analysis

0x0000: Temperature Sensor 1

0x0001: Pressure Gauge

0x0002: Flow Rate

0x0003: Motor Status

GUI & CLI Applications

Choose the interface that fits your workflow.

Modern GUI - Intuitive graphical interface for interactive testing
Powerful CLI - Command-line tool for scripting and automation
Same core engine - Consistent behavior across both interfaces
Batch operations - CLI supports scripted read/write sequences

Device Discovery & Diagnostics

Powerful tools to find and diagnose Modbus devices on your network.

Slave Scanner - Automatically scan for responsive Modbus slave IDs (1-247)
Register Scanner - Discover valid register ranges on any device
Connection Statistics - Real-time response time monitoring (avg, min, max)
Connection Quality - Packet loss detection and connection health status
Auto-reconnect - Automatic reconnection on connection loss with configurable retries

Scanning slaves 1-247...

Found: Slave ID 1

Found: Slave ID 5

Found: Slave ID 10

Scan complete: 3 devices found

Flexible Licensing

One license, multiple devices - manage your installations easily.

3 Device Activations - Use your license on up to 3 computers
Self-Service Portal - Manage your devices online at any time
Easy Deactivation - Free up a slot by deactivating old devices
Hardware Tolerance - Minor hardware changes won't affect your license
Offline Support - Works offline with 30-day grace period

Device 1: Work PC ✓

Device 2: Laptop ✓

Device 3: Available

Data Logging to CSV

Export your polling data for analysis in Excel, databases, or any data tool.

Automatic timestamps - Every reading logged with precise timestamp
Continuous logging - Log during polling for trend analysis
One-click export - Export collected data to CSV anytime
Excel compatible - Opens directly in Excel for charts and analysis
Custom filenames - Auto-generate with date/time or choose your own

Timestamp,Addr_0,Addr_1,Addr_2

2026-02-04 10:23:45,1234,5678,9012

2026-02-04 10:23:46,1235,5679,9013

2026-02-04 10:23:47,1236,5680,9014

Connection Profiles

Save your device configurations and switch between them instantly.

Save presets - Store connection settings, aliases, and formats
Quick switching - Change between devices with one click
Import/Export - Share profiles with colleagues
Default polling - Save your preferred polling configuration per device
Portable - Profiles stored as JSON, easy to backup

Profile 1: PLC Floor 1

Profile 2: Inverter #3

Profile 3: SCADA Gateway

Profile 4: Test Bench

Watchdog Alerts

Get notified when values change or exceed your defined thresholds.

Change detection - Alert when any monitored value changes
High/Low alarms - Trigger when value exceeds or drops below limits
Range monitoring - Alert when value goes outside defined range
Cooldown period - Prevent alert flooding with configurable cooldown
Multiple rules - Set different conditions for different registers

⚠️ Temperature > 80°C (Current: 85)

⚠️ Pressure changed: 4.2 → 5.1 bar

✓ Motor Status: Running

Monitoring 5 rules...

Hex Input & Register Maps

Work with data in any format and import device documentation directly.

Hex input - Write values as 0xFF, FFh, or plain decimal
Binary input - Enter values as 0b1010 for bit manipulation
Register map import - Import CSV with address names, formats, and scaling
Scale factors - Automatic conversion (e.g., raw × 0.1 = actual)
Units display - Show values with units (°C, bar, rpm)
Min/Max validation - Define expected ranges for each register

Write: 0xFF or 255 or FFh

Binary: 0b11111111

Scaled: 1234 × 0.1 = 123.4°C