A recent application needed to send messages to an Epson DM-D110 display. The device is connected via a serial cable. My problem was I didn't have the device, or indeed even a serial port on my computer. How to test sending data to a serial port?
Turned out there's a very simple solution, use a null-modem emulator. This will, in effect, create 2 virtual serial ports and connect them. Your application can then write to one port and you can use something like PuTTY to read the output from the other:
null modem emulator
application ---> COM4 <----> COM5 --->PuTTY
I can now run my application and see the output (in PuTTY console) that would have been sent to the display.
