The short answer is . ModRSsim and ModRSsim2 are released as open-source software under the GNU Affero General Public License.
To ensure you have the most secure and feature-rich version without worrying about registration prompts, download from official repositories: modrssim/src/mod_RSsim/About.cpp at master - GitHub
Because no registration is required, you can immediately access the following professional-grade simulation features: modrssim registration key new
Edit and display all four Modbus data types (Coils, Discrete Inputs, Input Registers, and Holding Registers) in various formats like Hex and Decimal.
Simulate up to 255 Modbus IDs simultaneously, which is ideal for testing complex SCADA setups without needing hundreds of physical PLCs. The short answer is
Includes a diagnostics screen that shows real-time traffic for Modbus commands and responses.
You do not need to purchase or find a "new" registration key to use the full features of the software for development or testing. Simulate up to 255 Modbus IDs simultaneously, which
Full support for Modbus RTU (RS-232) and Modbus TCP/IP connections.