The interface

If you have an old portable computer you can use it to keep a log of the date and the time of each lightning strike detected.
The configuration of this computer is not very important (I used an i386SX with 2 Mb of RAM and an hard disk of 20 Mb), but it must be battery powered with external AC adapter, because during storms the main voltage often drops and a normal PC could reboot loosing all the data. A battery powered computer can still work for a while (depending on battery age, but some minutes are usually enough, so even old laptops work fine).

I've written a small program (using Borland Pascal 7.0) that runs under DOS and polls a specified serial port. It's sensible on the falling edge of the counter pulse (high to low) that must be connected to the DCD line. On the RTS line and of the TXD line of the same port a positive and negative voltage is supplied for powering the pulse switch interface.

Here are the command usage and the command line arguments:

Use:      LIGHTNIN COMx [/P]
 or:      LIGHTNIN COUNTER=x

COMx is the COM port where the C.I.G.R.E. lightning flash
counter is connected. Valid COM ports are 1..4.
If the /P switch is specified a copy of the log is also sent to
the printer (on LPT1).

The COUNTER option is used to set the counter to "x".

• Download lightnin.pas (17,137 bytes): the full pascal source.
• Download lightnin.exe (13,280 bytes): the compiled program.

Please remark that this program is intended to run only under MS-DOS and it may not work in command prompt windows of modern operating systems.

Please read my disclaimer.

The structure of the log file (lightnin.log) can be easily imported with commercial software such as Excel that can be very useful to do statistics. This is an example of the log file:

Wed Jun 16 22:19:11 1999 -- 1455 -- Log session started.
Sat Jun 19 18:18:37 1999 -- 1456 -- Lightning strike detected.

Mon Jun 21 12:22:40 1999 -- 1457 -- Lightning strike detected.
Mon Jun 21 12:25:23 1999 -- 1458 -- Lightning strike detected.
Mon Jun 21 12:27:04 1999 -- 1459 -- Lightning strike detected.

Wed Jun 23 18:05:26 1999 -- 1459 -- Log session stopped.

Remark: One hour after the last detected strike a blank line is insered to separate different storms.

With Excel you can just import the log file as a text file and manually specify the size of each column: one for the date and one for the time; the other columns are not very important and can be deleted, but keep only the records that were marked with a " -- Lightning strike detected.". The "FREQUENCY(xx:xx;yy:yy)" function allows counting the events and separate them in classes.

This is an example.