Measurement Computing ZonicBook 618E rev.3.4 - Manual (Page 121)

Data Acquisition 987995 Glossary G-3
Start of Scan In relation to ZonicBook/618E, “start of scan” is a signal that is internal to the unit. It signals
the start of a scan group and therefore pulses once every scan period. It can be used to clear
the counters and latch the counter value into the acquisition stream.
Trigger An event to start a scan or mark an instant during an acquisition. The event can be defined in
various ways; e.g., a TTL signal, a specified voltage level in a monitored channel, a button
manually or mechanically engaged, a software command, etc. Some applications may use
pre- and post-triggers to gather data around an instant or based on signal counts.
TTL Transistor-Transistor Logic (TTL) is a circuit in which a multiple-emitter transistor has replaced
the multiple diode cluster (of the diode-transistor logic circuit); typically used to communicate
logic signals at 5 V.
Unipolar A range of analog signals that is always zero or positive (e.g., 0 to 10 V). Evaluating a signal in
the right range (unipolar or bipolar) allows greater resolution by using the full-range of the
corresponding digital value. See bipolar.