The Base Address
A16 Address Space
Outside the Command
Module
A16 Address Space Inside the Command Module or Mainframe
When reading or writing to a switch 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
Figure B-1 shows the register address location within A16 as it might be mapped by an embedded controller. Figure B-2 shows the location of A16 address space in the E1406 Command Module.
When the E1406 Command Module is not part of your VXIbus system (see Figure B-1), the digitizer’s base address is computed as:
C00016 + (LADDR * 64)16 or 49,152 + (LADDR * 64)
where C00016 (49,152) is the starting location of the register addresses, LADDR is the digitizer’s logical address, and 64 is the number of address bytes per VXI device. For example, the digitizer’s factory-set logical address is 40 (2816). If this address is not changed, the digitizer will have a base address of:
C00016 + (40 * 64)16 = C00016 + A0016 = CA0016
or (decimal)
49,152 + (40 * 64) = 49,152 + 2560 = 51,712
When the A16 address space is inside the E1406 Command Module (see Figure
1FC00016 + (LADDR * 64)16 | or | 2,080,768 + (LADDR * 64) |
where 1FC00016 (2,080,768) is the starting location of the VXI A16 addresses, LADDR is the digitizer’s logical address, and 64 is the number of address bytes per
1FC00016 + (40 * 64)16 = 1FC00016 + A0016 = 1FCA0016
or (decimal)
2,080,768 + (40 * 64) = 2,080,768 + 2560 = 2,083,328
122 | Appendix B |
