Measurement-computing USB-2527 Instrukcja Użytkownika Pobierz pdf (Strona 55)

USB-2527 User's Guide Specifications

Digital input/output

Table 5. Digital input/output specifications

Number of I/O

Ports

Three banks of eight.

Each port is programmable as input or output

Input scanning modes

Two programmable

 Asynchronous, under program control at any time relative to input scanning

 Synchronous with input scanning

Input characteristics

220 Ω series resistors, 20 pF to common

Logic keeper circuit

Holds the logic value to 0 or 1 when there is no external driver

Input protection

±15 kV ESD clamp diodes parallel

Input high

+2.0 V to +5.0 V

Input low

0 to 0.8 V

Output high

>2.0 V

Output low

<0.8 V

Output current

Output 1.0 mA per pin, sourcing more current may require a PS-9V1AEPS-2500

power supply option

Digital input pacing

Onboard clock, external input scan clock (XAPCR)

Digital output pacing

Four programmable sources:

 Onboard output scan clock, independent of input scan clock

 Onboard input scan clock

 External output scan clock (XDPCR), independent of external input scan clock

(XAPCR)

 External input scan clock (XAPCR)

Digital input trigger sources and

modes

See Table 8

Digital output trigger sources

Start of input scan

Sampling/update rate

4 MHz maximum (rates up to 12 MHz are sustainable on some platforms)

Pattern generation output

Two of the 8-bit ports can be configured for 16-bit pattern generation. The pattern

can also be updated synchronously with an acquisition at up to 4 MHz.

Counters

Counter inputs can be scanned based on an internal programmable timer or an external clock source.

Table 6. Counter specifications

Channels

4 independent

Resolution

32-bit

Input frequency

20 MHz maximum

Input signal range

-5 V to 10 V

Input characteristics

10 k pull-up, ±15 kV ESD protection

Trigger level

TTL

Minimum pulse width

25 ns high, 25 ns low

De-bounce times

16 selections from 500 ns to 25.5 ms, positive or negative edge sensitive, glitch

detect mode or de-bounce mode

Time-base accuracy

50 ppm (0 ° to 50 °C)

Counter read pacer

Onboard input scan clock, external input scan clock (XAPCR)

Trigger sources and modes

See Table 8

Programmable mode

Counter

Counter mode options

Totalize, clear on read, rollover, stop at all Fs, 16- or 32-bit, any other channel can

gate the counter

1 2 ... 50 51 52 53 54 55 56 57 58 59 60 ... 63 64

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