HP E1418A - Manual (Page 118)

The Base Address
When reading or writing to a module register, a hexadecimal or decimal
register address must be 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.
A16 Address Space
Outside the Command
Module
When the HP E1405/E1406 Command Module is not part of your VXIbus
system (Figure B-1), the HP E1418A’s base address is computed as:
Base Address = C000
16
+ (LADDR
16
* 40
16
)
or (decimal)
49,152 + (LADDR * 64)
where C000
16
(49,152) is the starting location of the register addresses,
LADDR is the module’s logical address (set either by the switches or using
dynamic addressing), and 64 is the number of address bytes per VXI device.
For example, the HP E1418A’s factory set logical address is 72 (48
16
),
therefore it will have a base address of:
C000
16
+ (48
16
* 40
16
) = C000
16
+ 1200
16
= D200
16
or (decimal)
49,152 + (72 * 64) = 49,152 + 4608 = 53760
A16 Address Space
Inside the Command
Module or Mainframe
When the A16 address space is inside the HP E1405/E1406 Command
Module (Figure B-2), the module’s base address is computed as:
Base Address = 1FC000
16
+ (LADDR * 40)
16
or
2,080,768 + (LADDR * 64)
where 1FC000
16
(2,080,768) is the starting location of the VXI A16
addresses, LADDR is the module’s logical address (set either by the
switches or using dynamic addressing), and 64 is the number of address
bytes per register-based device. The HP E1418A’s factory set logical
address is 72. If this address is not changed, the module will have a base
address of:
1FC000
16
+ (48
16
* 40
16
) = 1FC000
16
+ 1200
16
= 1FD200
16
or
2,080,768 + (72 * 64) = 2,080,768 + 4608 = 2,085,376
Appendix B HP E1418A Register-Based Programming 117
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com