Re: abort: instantiation fault in writeln_body(X, T2, eclipse)

Dear Christian,

I don't think we can help much with your problem unless we have your code,
and also the version and platform for the ECLiPSe you are using.

>"instantiation fault in writeln_body(XI, T2, eclipse)" 

This is, as you say, caused by a call to writeln/2 with the first argument
uninstantiated. So it is unlikely to be caused by the code fragment you
sent, but by something else.

>we use a timer of 100ms (set_timer(real, 0.1))

You should not be using set_timer/2 directly, unless you have a very old
(>3 years at least) version of ECLiPSe. You should use the after events
for this sort of things (event_after_every/2 should do what you want). 
*Note* that you should never use set_timer and the after events at the same
time. It is possible that something else is trying to use after events in
your program. 

Cheers,

Kish