Programs: Serial Port

How to set it up:

In order to use a serial port (see fig. 1) to interface with the counter program you're going to need the following items:

The counter program increments when ever the ring indicator (pin 9 of the serial port) detects a change in signal. The signal is supplied from the DTR (data terminal ready - pin number 4). A normally off switch is used to keep the signal interrupted. In the case of a reed switch, as a magnet moves past the reed, a connection between pins 4 and 9 is made, and a DTR signal is sent to the ring indicator.

Using the components listed above, connect the cable to the serial port as shown in picture of the inside of the serial port plug (fig. 4). On the other end of the cable connect the switching device.

fig. 1 - This is a serial port! Labeled is Pin 4 and 9.
fig. 1 - This is a serial port! Labeled is Pin 4 and 9.

fig. 2 - This is a plug... Labeled (again) is Pin 4 and 9.
fig. 2 - This is a plug... Labeled (again) is Pin 4 and 9.

fig. 3 - This is my reed switch and the magnet it came with.
fig. 3 - This is my reed switch and the magnet it came with.

fig. 4 - This is inside the Radio Shack plug.
fig. 4 - This is inside the Radio Shack plug.