The Base Address
When you are reading or writing to a multiplexer register, a hexadecimal or
decimal register address is specified. This address consists of a base
address plus a register offset. The base address used in register-based
programming depends on whether the A16 address space is outside or inside
the HP E1405/E1406 Command Module or HP E1300/E1301 Mainframe.
A16 Address Space
Outside the Command
Module or Mainframe
When the Command Module or mainframe is not part of your VXIbus
system (Figure D-1), the multiplexer’s base address is computed as:
1
C000
16
+ (LADDR * 64)
16
or
49,152 + (LADDR * 64)
where C000
16
(49,152) is the starting location of the register addresses,
LADDR is the multiplexer’s logical address, and 64 is the number of
address bytes per VXIbus device. For example, the multiplexer’s factory
set logical address is 112. With this address, the multiplexer has a base
address:
C000
16
+ (112 * 64)
16
C000
16
+ 1C00
16
= DC00
16
or (decimal)
49,152 + (112 * 64)
49,152 + 7,168 = 56,320
Figure D-2. Mainframe/Command Module A16 Address Space
Appendix D
Strain Gage Register-Based Programming 121
1 The "
16
" at the end of the address indicates a hexadecimal number.
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