ttl signal always the same length in biopac

[miriam2010]

I have issues with the ttl signal send from medialab to biopac.
For some reason the (digital) signal detected by biopac always has the same length, irrespective of how I define it (e.g. <1:888:5> and<1:888:500> - no difference), it is usually always 2 sec long, with some exceptions in which the signal is very short though it should have the same length the others have.
What can I do?

A related question I have is: Can I "ask" the signal to be send a couple seconds after the item-onset? How?

Thank you very much!
Best,
Miriam