About Passively Monitoring Serial Ports

VCS interfaces directly with the hardware UART by means of a modified serial port driver. The drivers are adaptations of the standard Microsoft Windows serial driver for each supported operating system. This provides both 100% compatibility so that your Internet connections and other serial communications software not only works but performance is unchanged.

Passive monitoring means that VCS is read-only, meaning it taps into both transmit and receive data and also looks at the modem control and status signals without attempting to change anything. Contrast this with the Source modes of VCS Async and Async Plus, in which VCS can also transmit.

Note that passive monitoring comes in several flavours with VCS:

Viewer and Async Plus (in Viewer mode) look at a selected port on a PC while communications software runs on the port.

VCS Async and Async Plus connect by a supplied cable set to one or two external devices (which can include a different serial port on the same PC that runs VCS).
 

Dual Port Monitor

 Monitor two connected devices using two ports on the PC running VCS

Passively monitor data and signals between attached DTE and DCE devices while the two devices are communicating. Use this configuration when you have two serial ports on the PC running VCS Async or VCS Async Plus. This mode is not available with VCS Viewer.

Single Port Monitor DTE

 Tap into a DTE/DCE link to monitor the DTE device

Passively monitor data and signals from the DTE while the DTE and DCE devices are communicating. Use this configuration when you have one serial ports on the PC running VCS Async or VCS Async Plus. This mode is not available with VCS Viewer.

Single Port Monitor DCE

 Tap into a DTE/DCE link to monitor the DCE device

Passively monitor data and signals from the DCE while the DTE and DCE devices are communicating. Use this configuration when you have one serial ports on the PC running VCS Async or VCS Async Plus. This mode is not available with VCS Viewer.

Viewer Mode

VCS Viewer, which is also available with VCS Async Plus, effectively spies on an internal serial port. You can choose any serial port that uses a physical UART and is available to Windows. The idea is to see the data being sent and received, along with whatever signals are being used by the connection.

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