HP E1418A manual A16 Address Space Outside the Command Module

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 = C00016 + (LADDR16 * 4016)

or (decimal)

49,152 + (LADDR * 64)

where C00016 (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:

C00016 + (4816 * 4016) = C00016 + 120016 = D20016

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 = 1FC00016 + (LADDR * 40)16

or

2,080,768 + (LADDR * 64)

where 1FC00016 (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:

1FC00016 + (4816 * 4016) = 1FC00016 + 120016 = 1FD20016

or

2,080,768 + (72 * 64) = 2,080,768 + 4608 = 2,085,376

Appendix B HP E1418A Register-Based Programming 117