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Appendix C
Register-Based Programming
Appendix Contents
The Agilent E1446A Summing Amplifier/DAC (amplifier) is a
register-based device which does not support the VXIbus word serial
protocol. When a SCPI command is sent to the amplifier, the amplifier
driver in the Agilent E1445A Arbitrary Function Generator (AFG) or
in the Agilent E1405/06 Command Module parses the command and
writes the information to the amplifier registers.
Register-based programming is a series of reads and writes directly to
the amplifier registers. This increases throughput speed since command
parsing is eliminated and the registers can be accessed from the VXI
backplane (with an embedded controller or Instrument BASIC).
This appendix contains the information you need for register-based
programming. The contents include:
• Register Addressing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1
• Computer Configurations. . . . . . . . . . . . . . . . . . . . . . . . . . . C-4
• Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-6
• Programming the Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . C-12
• Example Programs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-17
Register Addressing
Register addresses for register-based devices are located in the upper
25% of VXI A16 address space. Every VXI device (up to 256 devices) is
allocated a 32 word (64 byte) block of addresses. The amplifier uses six
of the 32 (word) addresses allocated.
Figure C-1A shows the register address location within A16. Figure
C-1B shows the location of A16 address space in the Agilent E1405/06
Command Module.
The Base Address When you are reading or writing to an amplifier register, a hexadecimal
or decimal register address is specified. This address consists of a A16
base address plus a register offset or register number.
Register Addressing Register-Based Programming C-1