Opcom Free !free!4all Portable

Right-click the device > Properties > Port Settings > Advanced. Change the COM port number to COM 3, 4, or 5 (Opcom 1.39 prefers low numbers). Also set Latency Timer to "1" (very important for stable data).

: It is often modified to work on various Windows versions (XP, 7, 10, and 11) by including pre-configured drivers, bypassing the common "driver signature" headaches found in older versions. opcom free4all portable