Справочник Пользователя для National Instruments NI 781xR

You can add additional I/O channels and signal conditioning using the 
CompactRIO R Series Expansion Chassis and CompactRIO I/O modules.

Refer to Appendix A, 

, for detailed NI 781xR specifications.

Using PXI-compatible products with standard CompactPCI products is an 
important feature provided by PXI Hardware Specification Revision 2.1 
and PXI Software Specification Revision 2.1. If you use a PXI-compatible 
plug-in card in a standard CompactPCI chassis, you cannot use 
PXI-specific functions, but you still can use the basic plug-in card 
functions. For example, the RTSI bus on the R Series device is available in 
a PXI chassis, but not in a CompactPCI chassis.

The CompactPCI specification permits vendors to develop sub-buses that 
coexist with the basic PCI interface on the CompactPCI bus. Compatible 
operation is not guaranteed between CompactPCI devices with different 
sub-buses nor between CompactPCI devices with sub-buses and PXI. 
The standard implementation for CompactPCI does not include these 
sub-buses. The R Series device works in any standard CompactPCI chassis 
adhering to the PICMG CompactPCI 2.0 R3.0 core specification.

PXI-specific features are implemented on the J2 connector of the 
CompactPCI bus. Table 1-1 lists the J2 pins used by the NI PXI-781xR. 
The NI PXI-781xR is compatible with any CompactPCI chassis with a 
sub-bus that does not drive these lines. Even if the sub-bus is capable of 
driving these lines, the R Series device is still compatible as long as those 
pins on the sub-bus are disabled by default and are never enabled.

Damage can result if the J2 lines are driven by the sub-bus.