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Chapter 2
Installation and Configuration
2-14
ni.com
4.
Click the PXI system controller. The chassis (or multiple chassis, in a 
multichassis configuration) is listed below it. Identify each chassis by 
right-clicking its entry, then selecting the appropriate chassis model 
through the Identify As submenu. Further expanding the PXI System 
branch shows all devices in the system that can be recognized by 
NI-VISA. When your system controller and all your chassis are 
identified, the required 
pxisys.ini
 file is complete.
The PXI specification allows for many combinations of PXI chassis and 
system modules. To assist system integrators, the manufacturers of 
PXI chassis and system modules must document the capabilities of their 
products. PXI Express devices must provide a driver and 
.ini
 file for 
identification. These files are provided as part of the PXI Platform Services 
software included with your system controller. The minimum 
documentation requirements for PXI-1 are contained in 
.ini
 files, which 
consist of ASCII text. System integrators, configuration utilities, and 
device drivers can use these 
.ini
 files.
The capability documentation for a PXI-1 chassis is contained in a 
chassis.ini
 file provided by the chassis manufacturer. The information 
in this file is combined with information about the system controller to 
create a single PXI-1 system initialization file called 
pxisys.ini
 
(PXI System Initialization). The NI system controller uses MAX to 
generate the 
pxisys.ini
 file from the 
chassis.ini
 file.
Device drivers and other utility software read the 
pxiesys.ini
 and 
pxisys.ini
 file to obtain system information. For detailed information 
about initialization files, refer to the PXI specification at 
www.pxisa.org
.
Trigger Configuration in MAX
Each chassis has one or more trigger buses, each with eight lines 
numbered 0 through 7 that can be reserved and routed statically or 
dynamically. Static reservation pre-allocates a trigger line to prevent its 
configuration by a user program. Dynamic reservation/routing/deallocation 
is on the fly within a user program based upon National Instruments APIs 
such as NI-DAQmx. Static reservation of trigger lines can be implemented 
by the user in MAX through the Triggers tab. Reserved trigger lines will 
not be used by PXI modules dynamically configured by programs such as 
NI-DAQmx. This prevents the instruments from double-driving the trigger 
lines, possibly damaging devices in the chassis. In the default 
configuration, trigger lines on each bus are independent. For example, 
if trigger line 3 is asserted on trigger bus 0, by default it will not be 
automatically asserted on any other trigger bus.