Because Spy mode operates at the system level, it requires specific drivers that are not always included in the basic installation. Installation Drivers typically need to be installed with Administrator privileges
Click the Spy button on the Port tab. The status should change to indicate it is monitoring.
\\.\USB0 (or USB1 , USB2 etc. – check your device instance path) realterm spy drivers
Ensure no application is currently using the port you want to monitor.
Before we discuss "spy drivers," we need to understand the software itself. Realterm is an open-source terminal application specifically designed for debugging, testing, and analyzing serial communication (RS232), ethernet (TCP/IP), and character-oriented data streams. Because Spy mode operates at the system level,
RealTerm handles both scenarios, but the "driver" requirement lies in the hardware, not the software.
The SPY feature in Realterm loads a filter driver. Instead of standard data, here are the most useful commands and parameters to enter: Instead of standard data
Monitoring Serial Traffic with RealTerm "Spy" Mode Debugging serial communications often feels like trying to solve a puzzle while half the pieces are hidden. While standard terminals like TeraTerm or PuTTY are great for basic interaction, they can't show you what another application is doing with a COM port. This is where —and its specialized drivers—become essential tools for any embedded engineer. What is RealTerm Spy Mode?
If you have trouble with RealTerm's drivers, these tools offer similar "sniffing" capabilities: SerialTool