[en] A multidetector gamma-ray residual radioactivity system demands the development of a specific adapter to count coincidence events efficiently. The parameters to be acquired are gamma-ray energies and detection time intervals between pairs of detectors obtained through Analogue to Digital Converters (ADC) and Time Interval to Digital Converter (TDC), respectively. The data acquisition trigger must be generated internally because no external trigger, like that provided by the beam or the reaction in on-line multidetector systems, is available. The adapter that we developed intercepts the fast NIM time analogue and logical (busy and inhibit) signals from the spectroscopy amplifier and, after appropriate processing, controls the ADCs gates and generates start/stop signals for the TDC (8 input). The module implements a multilevel trigger system, each deeper level corresponding to a refined coincidence test, driven by a simple finite-state machine. The first level trigger corresponds to the detection of gamma-rays by at least two detectors in a 200 ns time window. This trigger signal, however, is not suitable to start the TDC since it is simultaneous to the last time signal. The TDC is started by the first of the time signals delayed by 200 ns in coincidence with the first level trigger. The second-level trigger consists of a majority coincidence, n > 1, of the linear amplifier busy signals with pile-up rejection, where only the detectors that triggered the adapter are taken into account. The end of conversion of all digitizers pulls the third-level trigger, causing the data acquisition to start. The logic circuits are implemented by GALs (Generic Array Logic), and delays and time coincidence windows by fast transistors. All the circuits are placed in a single printed board, although the module occupies 4 CAMAC slots due to the large number of connectors in the front panel. The ADCs controlled by this system allow to obtain energy spectra like the usual gamma coincidence ones and, in spite of the time spectra obtained by the TDC being complex, the time difference spectra of a pair of detectors is similar to that obtained by time to pulse height converters. When tested with three large volume HPGe detectors, the energy gated time resolution was 5 ns. (author)