Measurement-computing PPIO-AI08 Manuale Utente Scaricare il pdf (Pagina 13)

5.3.1 A/D Data Registers

BASE + 0

A/D8A/D7A/D6A/D5A/D4A/D3A/D2A/D1

MSB

01234567

READ

On read, the most significant A/D byte is read. Note that since data is read through

the parallel port four bits at a time, two reads are required to obtain the entire byte

from this register.

The table below has coding for input voltages.

0 volts

−Full Scale

½ Full Scale0 Volts8002048

y Full Scaley Full ScaleFFF4095

UNIPOLARBIPOLARHEXDECIMAL

WRITE

Writing to this register starts a 12-bit A/D conversion.

A note of caution:

Place a program loop of at least 25

s delay between consecutive 12

bit A/D conversions to avoid over-running the A/D converter.

BASE + 1

0000A/D12

LSB

A/D11A/D10A/D9

01234567

A read/write register.

READ

On read, it contains the least significant four digits of the Analog input data.

These four bits of analog input data must be combined with the eight bits of analog

input data in

BASE + 0, forming a complete 12 bit number. The data is in the formof

0 = minus full scale. 4095 = +FS.

WRITE

Writing any data to the register causes an immediate 8-bit A/D conversion.

1 2 ... 8 9 10 11 12 13 14 15 16 17 18 19 20

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Measurement-computing PPIO-AI08 Manuale Utente Pagina 13