Serial tunneling may not work with all vendor’s serial-connected Windows applications. Also, serial tunneling is not supported for BACnet MS/TP usage—however, BACnet router functionality provided by a station running a BacnetNetwork with multiple network ports (e.g. IpPort, MstpPort) provides IP access to MS/TP connected devices.

When initiating a connection through the serial tunnel, client-side usage is transparent except for the “virtual COMn” port used, and if “Interactive” is left enabled (typical) the resulting serial tunnel configuration dialog right before the connection is attempted. Figure 152 shows an example serial connection being initiated from the Windows Hyperterminal application. Tunneling client messages may appear if the connection fails.

Figure 152. Example Windows XP serial application (Hyperterminal) initiating tunnel connection

Speed of the tunnel connection may be slower that a direct serial connection, due to the overhead of wrapping and unwrapping messages in Niagara Fox and TCP/IP protocols.

Tunneling client messages

When using a tunnel client, the specified user must be “authenticated” by the station before a connection is granted (established). If the user is not found, or if the entered password is incorrect, a popup message may appear on the client PC (Figure 153). Note the User Name and Password are both case-sensitive.

Figure 153. Authentication issue

As previously cautioned, note that “basic authentication” is used in any client connection to the station’s TunnelService, with possible security consequences. See Best security practices for tunneling.

Currently, only one tunnel connection is allowed per SerialTunnel. If another client application attempts a connection to that tunnel, a popup message may appear on that PC (Figure 154).

Figure 154. Tunnel busy