| Error Message | Likely Cause | Solution | | :--- | :--- | :--- | | "Invalid License File" | The file was generated for a different Machine ID. | You may have changed hardware (RAM, HDD, Network card). Contact support to reset your license. | | "License Expired" | You purchased a time-limited subscription (rare) or system date is incorrect. | Check your PC's system date and time. Ensure it is accurate. | | "Failed to load key" | File permissions issue. | Right-click Simply Modbus Master > "Run as Administrator," then re-attempt registration. | | "Machine ID Mismatch" | You reinstalled Windows or replaced the motherboard. | You need a license transfer. Email your old and new Machine ID to the vendor. |
: You will receive a second email from info@simplymodbus.ca containing your license key code. Note that this is a manual process and may take up to an hour during MST office hours or overnight. Activation : simply modbus master license key
Obtaining a license key is a manual process managed by the software developer. | Error Message | Likely Cause | Solution
The demonstration startup window and "unlicensed" popups disappear entirely, taking you straight to the main Read window. | | "License Expired" | You purchased a
"I purchased the license key for Simply Modbus Master to replace the expensive simulation software we were using for field testing. If you are an automation engineer or a technician who just needs a straightforward tool to read registers and test slave devices without the bloat of a full SCADA system, this is it.