Obtaining a new Modbus Slave license involves purchasing a perpetual, single-user key for $129.00 from Witte Software, which removes 30-day evaluation limitations. The key is activated via the F3 connection menu, with licenses from 2023 onwards compatible with the latest software versions. Purchase a new license and find installation instructions at Modbus Tools Modbus Tools FAQ - Modbus Tools
Modbus Slave: Getting a New License Key (2026 Guide) If you are developing or testing industrial automation systems, a Modbus Slave license key is essential for moving past trial limitations and enabling long-term simulation of PLC devices. For professional use, the industry standard is Modbus Slave by Witte Software, a simulator that allows engineers to test Modbus RTU and TCP/IP equipment without needing the physical hardware present. Why You Need a New License Key
While ModbusTools offers a free 30-day evaluation period, it includes strict operational limits:
Time-Limited Sessions: Connections are automatically disconnected after 10 minutes of activity.
Trial Expiration: After 30 days, the software will no longer allow any connections until a valid registration key is entered.
Legal Compliance: Using the software for commercial purposes after the 30-day period requires a paid registration to comply with international copyright laws. Pricing and License Types (2026)
As of early 2026, licenses are typically perpetual, meaning you pay once for a specific major version and can use it indefinitely. License Quantity Price per License (USD) 1 to 2 Licenses $129.00 Individual engineers or small setups. 3 to 9 Licenses $119.00 Small teams or testing labs. 10+ Licenses $109.00 Large-scale industrial engineering departments. modbus slave license key new
Note: A single-user license allows one person to use the software on multiple computers, provided they are the only person using those installations. Where to Buy a New License Key
To ensure you receive a genuine, supported key, purchase directly through official channels or authorized regional distributors.
Official Global Site: The Witte Software Ordering Page is the primary source for global digital delivery via email.
Regional Distributors: For commercial organizations requiring local invoices or specific tax documentation, retailers like Syssoft and Softlist provide licensed keys with delivery times typically ranging from 3 to 14 business days.
Bundled Options: If you also need a Master simulator, Simply Modbus offers bundled licenses for their Master, Slave, and TCP Client programs starting around $162.00. How to Activate Your New Key
Once you have received your key via email, activation is a simple three-step process: Obtaining a new Modbus Slave license involves purchasing
Download the Latest Version: Ensure you have the newest installer from the ModbusTools Download section.
Open Registration: Launch Modbus Slave and press the F3 key on your keyboard.
Enter Details: Input the registration name and the new license key exactly as they appear in your purchase email. Transferring Your License
If you upgrade to a new workstation, you can move your license: Uninstall the software from the old machine. Install it on the new computer.
Re-enter your original key (keys purchased from 2023 onwards are compatible with current versions). Master software features? Witte Software ordering information - Modbus Tools
Price in USD: * 1 to 2 license: $ 129.00. * 3 to 9 licenses: $ 119.00 per license. * 10+ licenses: $ 109.00 per license. Modbus Tools FAQ - Modbus Tools Error C: "License Expired" on a Perpetual New
Cause: You installed a time-limited trial key by mistake, or the system clock was incorrectly set. Fix: Sync your system time with time.windows.com or pool.ntp.org. If the error persists, contact the vendor to confirm they issued a perpetual (non-expiring) key.
If your slave device is on a secure network without internet access, you will need an Offline Activation:
request.bin file.response.bin file.If you are building a product that acts as a Modbus slave (e.g., sensor, meter, gateway), you may need an OEM license key from a stack provider (like Embedded Solutions, MBSOFT, or EmServer).
In that case:
💡 Tip: For prototypes, use a free stack (libmodbus, FreeMODBUS) to avoid license costs. Move to commercial keys only for production.