Measurement Computing CIO-DAS16/M1 - Manual (Page 17)

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Table 4-2. Bit Weights
BIT POSITION DECIMAL VALUE HEX VALUE
0 1 1
1 2 2
2 4 4
3 8 8
4 16 10
5 32 20
6 64 40
7 128 8
To write control or data to a register, the individual bits must be set to 0 or 1 then combined to form a
byte. Data read from registers must be analyzed to determine which bits are on or off.
The method of programming required to set/read bits from bytes is beyond the scope of this manual. It is
covered in most Introduction To Programming books, available from a book store.
Board registers and their functions are listed in Table 4-3. Each register has eight bits which can
constitute a byte of data or can be eight individual write/read functions.
Table 4-3. Register Summary
ADDRESS READ FUNCTION-ALL MODES WRITE FUNCTION
BASE + 0 A/D Data Read as Word Start A/D Conversion
BASE + 1 Do not use None
BASE + 2 Control & Status Bits Control Bits
BASE + 3 Digital 4 Bits Input Digital 4 Bit Output
BASE + 4 None Clear Interrupt Status
BASE + 5 Interrupt Control-Pacer Source Set Interrupt & Pacer Source
BASE + 6 Channel Gain Queue Address Set Channel Gain Queue Address
BASE + 7 Channel Gain Queue Data Write Channel Gain Queue Data
BASE + 8 Total Counter Upper Half Total Counter Upper
BASE + 9 Total Counter Lower Half Total Counter Lower
BASE + A Pre-trigger Index Pre-trigger Index Start Value
BASE + B None-No read-back on 82C54 Total & Pre-trigger Counter Ctrl
BASE + C Counter 0 Data Counter 0 Data
BASE + D CTR 1 Data - A/D Pacer Clock CTR 1 Data - A/D Pacer Upper
BASE + E CTR 2 Data - A/D Pacer Clock CTR 2 Data - A/D Pacer Lower
BASE + F None-No read-back on 82C54 Pacer Clock Control
82C54 and 82C55 – 2
nd
Connector
BASE+400 82C55 Port A Data 82C55 Port A Data
BASE+401 82C55 Port B Data 82C55 Port B Data
BASE+402 82C55 Port C Data 82C55 Port C Data
BASE+403 None-No read-back on 82C55 82C55 Control Register
BASE+404 82C54 User Counter 0 Data 82C54 User Counter 0 Load
BASE+405 82C54 User Counter 1 Data 82C54 User Counter 1 Load
BASE+406 82C54 User Counter 2 Data 82C54 User Counter 2 Load
BASE+407 None-No read-back on 82C54 82C54 User Counter Control