Autosequencer

From Memory Alpha, the free Star Trek reference

Autosequencers are a part of Federation transporters.

When Ambassador T'Pel was beamed to a Romulan warbird, her signal started to degrade so additional power was diverted to the autosequencers. It was too late, and T'Pel was apparently lost. Nonetheless, a subsequent transporter diagnosis proved that the autosequencers were functioning normally. It was later discovered that T'Pel had been beamed away by the Romulans. (TNG: "Data's Day")