ttl signal always the same length in biopac

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

If you try to send the signal (e.g., "1" ) from port 888 for 5 vs 500ms in the TTL I/O test utility, do you find you get the same results? As far as the onset delay, no, I don't think there is a built in way to do that in MediaLab--especially with that degree of accuracy. DirectRT, I think could be rigged to do that depending on the design of your study. ML could approximate it by duplicating the item--fixing it for 200ms and then repeating it with an immediate TTL at the onset of the repeat. Does that make sense? Not a very elegant workaround though.

Thank you for your response.
In fact, in the test utility it works just fine. The signal length in Biopac when the signal is automatically send within the experiment however is almost random.