Measurement-computing CIO-DAS160x/1x Instrukcja Użytkownika Pobierz pdf (Strona 9)

3.8 BURST MODE GENERATOR

The burst mode generator is a clock signal that paces the A/D at the maximum multi-channel sample rate,

then periodically, performs additional maximum rate scans. In this way, the channel to channel skew

(time between successive samples in a scan) is minimized without taking a large number of undesired

samples (Figure 3-8).

Figure

3-8

. Burst Mode Timing

The CIO-DAS1600 burst mode generator takes advantage of the fast A/D. The burst mode skew is 4 µs

between channels for the CIO-DAS160#/12. It is 13.3 µs for the CIO-DAS1602/16.

3.9 DT-CONNECT

There is no hardware configuration or installation required for DT-Connect. Software enables/disables

DT-Connect, and of course, you must have a DT-Connect equipped accessory board, (Measurement

Computing’s MEGA-FIFO, for example) before using the DT-Connect.

DT-CONNECT IN MASTER MODE ONLY

The CIO-DAS1600 implements DT-Connect MASTER MODE only. DT-Connect is always enabled and

is never busy. The ENABLED and BUSY signal levels are fixed in hardware. Since DT-Connect is

always enabled, any A/D conversions are always transferred out through the DT-Connect port regardless

of the bus transfer method specified. The CIO-DAS1600 can only operate in DT-Connect schemes where

it is the sole master.

To assure that DT-Connect is properly initialized prior to any A/D transfer, the DT-Connect DT-Request

handshake line is reset each time the programmable gain (Base + 11 decimal) register is written to.

Therefore, it is not possible to use the DT-Connect for A/D sets which involve setting the gain between

samples. This is not really a problem because any such scheme would be low speed and therefore store

data to disk, obviating the need to use DT-Connect to store data on the MEGA-FIFO.

Please see the data sheet on the MEGA-FIFO, a 128 million-sample buffer board as an example of a

DT-Connect accessory.

Ch0 Ch1 Ch2 Ch3

4uS

Delay

Burst mode pacer fixed at

4 uS - CIO-DAS1600/12

13.3 uS - CIO-DAS1600/16

The length of the delay between

bursts is set by one of the internal

counters or may be controlled via

external trigger.

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