Measurement-computing USB-1608HS Instrukcja Użytkownika Pobierz pdf (Strona 19)

USB-1608HS User's Guide Functional Details

SYNC terminals (SYNC_IN and SYNC_OUT)

You can use the SYNC_IN connection to externally pace the A/D conversions. The SYNC_IN terminal supports

TTL-level input signals of up to 250 kHz.

Use the SYNC_OUT connection to output the clock used for A/D conversions.

One example of the use of these two pins would be to synchronize with a second USB-1608HS and acquire

synchronized data from 16 channels. You can connect the SYNC_OUT pin of one USB-1608HS to the

SYNC_IN pin of another USB-1608HS to acquire data synchronously from 16 channels.

Figure 10. Configuring for synchronous data acquisition

Trigger terminal (TRIG_IN)

The TRIG_IN connection is an external analog/digital trigger input.

With the analog trigger function, you can start and control acquisitions with an analog signal. The analog trigger

threshold is from -10 V to +10 V on the TRIG_IN pin. A 12-bit DAC sets the level for the threshold. The

threshold resolution in this mode is 4.88 mV.

The USB-1608HS has three trigger options that you must set.

 Trigger above or trigger below

 Level-sensitive or edge-sensitive

 Retrigger on or retrigger off

Each trigger operation mode is explained next. In each case, a ±2 V triangle waveform is used as the TRIG_IN

input source. The high threshold is set to 1.0 V, and the low threshold signal is set to -1.0 V.

In the following analog trigger signal diagrams, the bold portion of the waveform indicates the data acquired for

the given analog trigger mode.

SYNC_IN pin

SYNC_OUT pin

1 2 ... 14 15 16 17 18 19 20 21 22 23 24 ... 30 31

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Measurement-computing USB-1608HS Instrukcja Użytkownika Strona 19