Virtual Null Modem
Null-modem cable is basically used for communication of two RS-232 DTE devices with each other. To create null-modem connection between the devices you need to use two computers or two serial ports of a single computer connected with null-modem cable. ... Virtual null-modem allows user emulate virtual null modem connection and run the two applications simultaneously on the same computer. ... The most reliable way to create null-modem connection is using of virtual serial ports emulated by virtual serial port driver and null-modem cable.
http://www.virtual-null-modem.com/download/vnullmod20.exe - 1Mb - Download - Screenshot

Virtual Serial Port Kit
Virtual Serial Port Kit creates pairs of virtual serial ports in your system which are virtually connected to each other. Physical null modem cables are not required. You can connect any number of virtual port pairs. Virtual serial port pairs will look and work exactly like real hardware serial... - virtual communication is more fast (up to 250 Kb/s) and reliable than via real null modem cable. ... Virtual Serial Port Kit is useful also for users which work with Windows applications using serial COM ports joined by null modem cable especially if those applications require more than one...
http://www.virtual-serial-port.com/virtual-serial-port-kit.zip - 796Kb - Download - Screenshot

Virtual Serial Port Driver XP4.5
Virtual Serial Ports Driver XP creates two pure virtual serial ports in your system which are virtually connected to each other. For other Windows applications, virtual ports will be seen exactly as two real serial ports connected via null-modem cable. ... Virtual link between virtual serial ports is much faster then real null-modem cable connection and depends on your processor speed. ... With user-friendly GUI and on-the-fly help of Virtual Serial Port Driver XP it's very easy to configure a virtual serial ports pair.
http://www.mks.zp.ua/vspdxpd.exe - 1Mb - Download - Screenshot

Advanced Virtual COM Port
Advanced Virtual COM Port is the first software of its kind which includes both local and network virtual COM port functions. It can share your real COM ports or it can create virtual COM ports and connect them with a virtual null-modem cable locally or through a TCP/IP network or the Internet. ... Virtual serial ports created by the program look and work the same way as real ones look and work. ... You can connect to a shared port and use it just like it is on your machine.
http://www.advancedvirtualcomport.com/files/AdvancedVirtualComPort.zip - 1Mb - Download - Screenshot

Virtual Serial Port SDK
Using Virtual Serial Port SDK you can create a "new" serial port on your computer. This serial port is completely controlled by your application. Other 3rd party applications can connect to this serial port and believe it is a normal physical port. In this way you can emulate all kinds of... Virtual Serial Port SDK is available for . ... NET and VisualBasic 6. ... 0 are included. ... Samples in C#, VB. ... NET and ActiveX, on all Windows platforms Windows Mobile/Pocket PC, Windows XP/2k/NT and Windows ME/98.
http://franson.com/serialtools/SerialToolsSDK.zip - 2Mb - Download

Virtual Serial Ports Driver CE
Virtual Serial Ports Driver CE creates up to 20 pure virtual serial ports in your mobile system, this results in up to 10 virtual serial ports pairs. Each pair has 2 ports that are virtually connected to each other. For other applications, virtual serial ports will be seen exactly as two real... In this case all data sent by other applications to virtual serial port COM5 (VSP0) will arrive at virtual serial port COM6 (VSP9), and all data sent to virtual serial port COM6 will arrive at virtual serial port COM5 (VSP0).
http://www.eltima.com/download/vspdce.exe - 432Kb - Download - Screenshot

Virtual Serial Ports Driver XP
Virtual Serial Ports Driver (VSPD) creates two pure virtual serial ports in your system which are virtually connected to each other. For other Windows applications, virtual ports will be seen exactly as two real serial ports connected via null-modem cable. ... With VSPD you can connect one application to another using virtual serial ports pair. ... For example, you can create virtual pair COM5-COM6. ... You can select any port numbers for virtual pair. ... Applications will be able to exchange data.
http://www.eltima.com/download/vspdxp.exe - 1Mb - Download - Screenshot

Virtual Serial Port Driver XP4
Virtual Serial Port Driver XP4 creates two pure virtual serial ports in your system which are virtually connected to each other. For other Windows applications, virtual ports will be seen exactly as two real serial ports connected via null-modem cable. ... 0 you can connect one application to another using virtual serial ports pair. ... For example, you can create virtual pair COM5-COM6. ... You can select any port numbers for virtual pair. ... With Virtual Serial Port Driver XP 4. ... This solution can be used, for example, for GPS simulation programs.
http://www.virtualserialport.com/download/vspdxp.exe - 1Mb - Download - Screenshot

AlarIT Virtual Serial Driver (AVSD)
AlarIT Virtual Serial Driver is appointed for emulation of one, two or more (up to 200) serial streams. Hardware devices are not necessary. This product is based on Windows XP DDK and doesn't require using devices of other manufacturers. The whole product is created with the help of Microsoft... AlarIT Virtual Serial Driver realizes full emulation of Serial Port functions, connected with each other with the help of NULL-MODEM or full cable, including DTR, CTS, DSR, RTS. ... 0 with null-modem cable showed that they are practically identical.
http://www.alarit.com/downloads/products/avsd.zip - 448Kb - Download

Virtual Serial Ports Driver
Virtual Serial Port Driver by Virtual Serial Port Software, department of Eltima, is a sophisticated software solution aimed to create two pure virtual serial ports virtually connected to each other in your system. Therefore, without additional hardware installation you may use extra serial... Deploying virtual COM ports you can do the same you do with the real one and for other windows applications they will be seen exactly as two real serial ports connected via null-modem cable. ... Unlike standard physical serial ports, virtual ports can be assigned any number and you can create as many...
http://www.virtualserialport.com/download/vspdxp.exe - 2Mb - Download - Screenshot