The Null-modem emulator can be used to provide serial interface for device emulators.In this case the device emulation program uses one port of the pair andthe other port can be used by Windows or DOS application thatrequires a COM port to communicate with the device.For example, to send/receive faxes over IP you can connect WindowsFax application to t38modem (T38FAX Pseudo Modem,part of the t38modem project ) via virtual COM port pair.
These samples focus on communicating with a Windows-based application via serial ports. Just change the device name of “COM1” to the correct port and the name of the device you’d like to receive data from.
The software-implemented modem is called null-modem because it has no “modem” that sends any data down the serial port. The modem only receives data. An RS232 or RS422 phone line should be attached to the modem port to send and receive data.
A virtual serial port allows data from multiple simulated serial ports to be sent to and from a single computer. This is useful when data from multiple serial ports on a host computer is required.
Most serial ports are not standardised; each vendor has their own options. Often there are additional options for what speed the port can run at. A common limitation is that a port can only be set to run at one speed. There are a number of devices which have multiple serial ports, but these rarely provide standardisation of the ports. Multiple serial ports can be of the same speed (8, 9600, etc.), or a mix of speeds (one at 9600, one at 4800, etc.)
The following steps will set up a dual port serial card on a computer running Linux. It is important that the serial port driver has the option of running at different speeds, as this port will be used for different speeds on different network devices.
VSPE is a general-purpose serial port emulator that runs on Windows, Linux or Mac OS. It was developed for educational, training and developper's purpose, because it does not require any hardware components. The only requirement is a PC with a serial port connected to a modem or a computer on which VSPE is to run. The serial port need not be connected to a real machine. The PC can be running on a laptop or a desktop or in a virtual machine. 827ec27edc