COM Port Model

The COM port model allows a VSM simulation access to the one of the real, physical COM ports (e.g. COM1, COM2, etc.) of the PC it is running on so allowing the simulation to interact with real hardware. Incoming serial data is buffered and presented to the circuit as a digital signal, whilst serial digital data generated by a CPU or UART model appears at the PC's physical COM port. The COM port model can perform baud rate translation and as well as hardware or software handshaking on both the physical and virtual sides of the device.
The main features of the model are as follows:
  Full buffering of incoming/outgoing data with rate baud rate and protocol translation - you can have different settings for baud rate, stop bits, parity, etc. on the physical and virtual sides.
  Buffers incoming serial data, even when the simulation is paused, allowing you to single step a CPU's code and see exactly what happens as the data is processed.
 

Supports any Windows COM port.
 

Supports baud rates of 50 baud to 57,600 baud and higher on both physical and virtual interfaces.
 

Supports 7 or 8 data bits on both physical and virtual interfaces.
 

Supports one or no stop bits on both physical and virtual interfaces.
 

Supports XON/XOFF (with configurable characters) and RTS/CTS handshaking on both physical and virtual interfaces.

  Can be used for simple digital I/O as the model also provides access to the CTS, DSR, DCD and RI inputs and the RTS/DTR outputs of the physical serial port.
 
COM Pin Schematic

ISIS simulation with a virtual terminal connected, via a COM port model, to a debug session on a remote computer. In this instance, the COM port model is interfacing directly to the PC's real (physical) COM1 port which has been connected, via a serial lead, to a laptop computer.