Measurement Computing CIO-DAS16/M1 User Manual
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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