The Base Address - Keysight VXI Bus 75000 C Series User And Programming Manual

Keysight E1458A Register Information

The Base Address

When you are reading or writing to a module 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 Keysight E1405/E1406
Command Module.
A16 Address Space Outside the Command Module
When the Keysight E1405/E1406 Command Module is not part of your VXIbus
system (Figure B-1), the Keysight E1458A's base address is computed as:
where C00016 (49,152) is the starting location of the register addresses, LADDR
is the module's logical address, and 64 is the number of address bytes per VXI
device. For example, the E1458A's factory-set logical address is 144 (9016),
therefore it will have a base address of:
A16 Address Space Inside the Command Module or Mainframe
When the A16 address space is inside the Keysight E1405/E1406 Command
Module (Figure B-2), the module's base address is computed as:
where 1FC00016 (2,080,768) is the starting location of the VXI A16 addresses,
LADDR is the module's logical address, and 64 is the number of address bytes
per register-based device. Again, the Keysight E1458A's factory-set logical
address is 144. If this address is not changed, the module will have a base
address of:
122
C00016 + (LADDR * 40)16
or (decimal)
49,152 + (LADDR * 64)
C00016 + (9016 * 4016) = C00016 + 240016 = E40016
or
49,152 + (144 * 64) = 49,152 + 9216 = 58,368
1FC00016 + (LADDR * 40)16
or
2,080,768 + (LADDR * 64)
1FC00016 + (9016 * 6416) = 1FC00016 + 240016 = 1FE40016
or
2,080,768 + (144 * 64) = 2,080,768 + 9216 = 2,089,984
Keysight E1458A 96-Channel Digital I/O Module User Guide
Addressing the Registers