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Analog to Digital Converter¶

ND 108200

flowchart LR
    subgraph Channel
        direction TB
        0 -->|
        1 -->|
        2 -->|
        3 -->|
        4 -->|
        5 -->|
        6 -->|
        7 -->|
        EXTERNAL -->|
    end
    Channel --> Input_Filter --> MUX

    MUX --> Analog_Digital_Converter
    MUX -- Address A0-2 --> Control_Logic
    Control_Logic -- Start Conversion --> Analog_Digital_Converter

    Analog_Digital_Converter -.->|12 bit Data| Standard_NORD_Bus
    Control_Logic -.->|Interrupt| Standard_NORD_Bus
    Power_Supply -.->|Read Only|

    Input_Filter[Input Filter]
    MUX[MUX]
    Analog_Digital_Converter[Analog/ Digital Converter]
    Control_Logic[Control Logic]
    Power_Supply[Power Supply]
    Standard_NORD_Bus[Standard NORD-10/NORD-12 I/O Bus]

     _______
    |       |
    |  ND   |
    |_______|

Norsk Data

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ANALOG TO DIGITAL CONVERTER¶

Introduction¶

The ND 108200 – Analog to Digital Converter – is a low-cost medium-performance data acquisition system intended for laboratory, instrumentation, and process applications. The Converter requires one standard I/O slot.

Features¶

12 bits resolution
8 bipolar inputs
Input filter
Overvoltage protection
External "Start Conversion" facility for high sampling accuracy

Product Description¶

The Analog to Digital Converter is physically located on one standard-size NORD-10/NORD-12 module. The Converter is self-contained with power such that it may be plugged directly into a standard I/O slot.

The Converter may be operated in three different programmable modes:

Sampling is program controlled.

Sampling may be started by the EXTERNAL signal. An interrupt is sent to the CPU at End of Conversion. Sampling accuracy is in this case determined by the EXTERNAL signal.

The EXTERNAL signal may be used to generate an interrupt to the CPU, and the sampling is then program controlled.

Specifications¶

Hardware¶

Specification	Value
Resolution	12 bits
Number of channels	8
Input voltage	± 10V differential
Converted data	2's complement notation
Input filter	100 ms time constant
Conversion time for A/D	25 µs
Total data acquisition time	35 µs
Input overvoltage protection	100V (continuously)

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Analog to Digital Converter¶

Software¶

SINTRAN supports up to 8 ND 108200 (64 channels).

The FORTRAN calling sequence is according to ISO (Purdue) standard:

CALL AIRD (INUM, ILDAR, IRSAR, IVAL)

INUM: Number of channels
ILDAR: Integer array containing the channel number (0-63)
IRSAR: Integer array where converted data will be stored
IVAL: Error indicator

The ND 108200 may be operated in the desired mode by initializing the A/D Converter via the monitor call IOSET.

IOX Instructions¶

Channel Selection¶

IOX <set MUX channel<
A-register bits 0-2 select channel 0-7

Control Word¶

IOX <load control word<
A-register:
Bit 0    Enable interrupt
Bit 1    Not used
Bit 2    Start conversion
Bit 3    Not used
Bit 4    Master Clear
Bit 5    Enable EXTERNAL Interrupt
Bit 6    Enable EXTERNAL start of conversion
Bit 7-15 Not used

Status Word¶

IOX <read status>
A-register:
Bit 0    Interrupt enabled
Bit 1    Not used
Bit 2    Busy
Bit 3-4  Not used
Bit 5    EXTERNAL Interrupt enabled
Bit 6    EXTERNAL start of conversion enabled
Bit 7-15 Not used

Converted Data¶

IOX <read data>
A-register:
Bit 0    LSB
Bit 1-10 2's complement
Bit 11   MSB