Appendix E
Configuring a Two-Frame System
VME-MXI-2 User Manual
E-4
© National Instruments Corporation
VMEbus BTO Unit
In each mainframe, the VME-MXI-2 must be the sole bus timer on the
VMEbus regardless of its slot location within the mainframe. Be sure to
disable the bus timers on all other modules in the mainframes for
proper operation.
Address Mapping
If you are not using a VXIbus multiframe Resource Manager, you will
have to configure the four address mapping registers on the two
VME-MXI-2 modules. For simplicity sake, you can map the lower half
of each address space (Logical Address, A16, A24, and A32) to
Frame A and the upper half to Frame B. To accomplish this, you should
write the value 6100 hex into each of the Extender window registers
(VWR0, VWR1, VWR2, and VWR3) on the VME-MXI-2 in Frame A
and the value 6180 hex into each of the Extender window registers on
the VME-MXI-2 in Frame B. You should configure all addressable
resources in Frame A to be located in the lower half of their respective
address spaces. Likewise, all addressable resources in Frame B should
be located in the upper half of their respective address space.
In addition to address space mapping, you might want to map VMEbus
utility signals (SYSRESET*, SYSFAIL*, and ACFAIL*) and interrupt
requests between frames. For information on how to do this, refer to
Chapter 4, Register Descriptions, for information about the VXIbus
Interrupt Configuration Register (VICR) and VXIbus Utility
Configuration Register (VUCR).
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