![Com port emulator Com port emulator](/uploads/1/2/4/3/124393461/393351724.png)
If you are a software engineer or a developer looking to create/debug/test applications that use serial ports, then such virtual emulators can come helpful. VSPE(for 32-bit windows) is a free virtual serial ports emulator which is able to create various virtual devices to transmit and receive data. It has more capabilities such as opening the.
Screen-shot of the Termite utilityTermite is an easy to use and easy to configure RS232 terminal. Port=DeviceProlificSerial2If using the device name of a serial port is not an option, for example, becauseyour hardware has a real serial port instead of a virtual one, you canalternatively use the 'port scanning' protocol. To activate this protocol, set' Port=0' below the ' Settings' section. Port scanningchooses the first port for which the two following conditions hold:.the port is not already open (in use);.after setting the DTR line, the remote device pullsDSR up.Port scanning cannot be selected from the Settings dialog, youhave to edit the INI file to activate it.The tests for port scanning are primitive. They do not check what device or programis hooked at the other end.
The only thing that you know after a port scan is thatsomething is connected to the port and that no other program is currentlyusing that particular port.In the old days, it had become common practice to connect the DTRand DSR pins in the connectors of the cable (sometimes even atboth ends). This is bad practice, because with such cables you cannot evendiagnose cable connection problems. Yet, such cables still exist, and the portscan may be fooled by it.The DRT/DSR handshake usually works with USB-to-RS232 converter cables too.Non-standard Baud ratesThe MIDI protocol is essentially the RS232 protocol over a current-loop physicallayer and with a Baud rate of 31250 bps —for details, see the article'.Likewise, DMX512 is essentially the RS232 protocol over an RS485 physical layerand with a Baud rate of 250,000 bps.Termite presents you with a list of standard Baud rates, but it allows you toenter different values.
The key issue is that the RS232 hardware must supportthe Baud rate that you select. All RS232 hardware and all USB-to-RS232 converterplugs support the standard Baud rates, but only few support non-standard Baudrates. We have tested non-standard Baud rates successfully with USB-to-RS232converters based on the.Forwarding data between two RS232 (virtual) portsYou can use Termite to put a PC (or laptop) between two systems and monitor theirRS232 communication. The PC or laptop that Termite runs on must have two RS232ports. Instead of connecting both systems together, you connect both with thePC that runs Termite. Then, you have to choose one port as the primary port andthe other as the 'forward' port, see thedialog of Termite.With forwarding set up, all data received on the primary port is transmittedthrough the forward port.
All data received on the forward port is transmittedthrough the primary port. The 'sent/received colouring' of Termite is also stillin effect: data received on the primary port is in green and data received on thesecondary port is in blue.In this configuration, Termite would typically only be used to monitor thecommunication between two devices. If you type in text on the edit line andtransmit it, this text is only sent through the primary port.In the above diagram, Termite runs on a computer that sits between two othersystems/devices. If one of these systems is also a computer (running MicrosoftWindows), the set-up may be simplified by running Termite on that system. Thedual RS232 port needed for Termite may be replaced by a virtual COM port pair,such as the.A virtual null-modem creates two ports that exist only in software. Any datapresented to one port of this pair is retransmitted at the other port —the sameas how port forwarding works in Termite. If you connect an application to oneport of the pair and Termite to the other port, the application now talks toTermite.