Allan Gould contacted me with a software request yesterday, and I got around to having a play with it tonight. The attached program is the second version.
Its a 2 stage timer and counter. The request was for something that can count the number of subs taken in parallel with a program such as CCDSoft. The idea is to set up your exposure time in the stage 1 timer and the dwell time between captures in the stage 2 timer. Start the timer counter when you start a programmed imaging run, and it will count the number of times through the cycle.
If the stage 1 timer (exposure) is set to zero, the program will not start. The stage 2 timer (dwell timer) can be set to zero. Negative numbers are ignored and treated as zeros. I have deliberately avoided being too tricky and forcing strict time format for input so you can specify a 600s exposure rather than 10min if you want to.

Not sure yet if this is a good idea... but if you want to put a mixture of minutes and large numbers of seconds as well, then you'll get what you ask for!

The timer will sound the system's exclamation sound each time it changes from exposure to dwell and vice versa unless you check the Mute checkbox (aren't I kind?

).
The display has 2 groups of Exposure and dwell times. The small ones at the top are where you set the exposure and dwell times you want. The larger ones are the countdown timers. The cycle counter displays the current exposure number (or previous completed exposure during the dwell period).
Feel free to try it, and offer any feedback.
Al.