Measurement Computing USB-2527 - Manual (Page 56)

USB-2527 User's Guide Specifications
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Input sequencer
Analog, digital, and counter inputs can be scanned based on either an internal programmable timer or an
external clock source.
Table 7. Input sequencer specifications
Scan clock sources: two (see Note 4) Internal:
 Analog channels from 1 µs to 1 sec in 20.83 ns steps.
 Digital channels and counters from 250 ns to 1 sec in 20.83 ns steps.
External. TTL level input (XAPCR):
 Analog channels down to 1 µs minimum
 Digital channels and counters down to 250 ns minimum
Programmable parameters per scan: Programmable channels (random order), programmable gain
Depth 512 locations
Onboard channel to channel scan rate Analog: 1 MHz maximum
Digital: 4 MHz if no analog channels are enabled, 1 MHz with analog
channels enabled
External input scan clock (XAPCR)
maximum rate Analog: 1.0 MHz
Digital: 4 MHz if no analog channels are enabled, 1 MHz with analog
channels enabled
Clock signal range: Logical zero: 0 V to 0.8 V
Logical one: 2.4 V to 5.0 V
Minimum pulse width 50 ns high, 50 ns low
Note 4: The maximum scan clock rate is the inverse of the minimum scan period. The minimum scan
period is equal to 1 µs times the number of analog channels. If a scan contains only digital
channels, then the minimum scan period is 250 ns.
Some platforms can sustain scan rates up to 83.33 ns for digital-only scans.