Getting Started with NI 9501 Modules and NI SoftMotion
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© National Instruments
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11
NI SoftMotion Engine to FPGA Communication
Each User-Defined Variable communicates information between the NI SoftMotion Engine and
the LabVIEW FPGA Module. These UDVs are used directly with the Drive Interface FPGA VIs
in specific loops on the block diagram. Complete the following steps to open the FPGA VI and
display the block diagram.
1.
Expand the
FPGA Target
item in the LabVIEW Project Explorer window.
2.
Double-click the
Stepper Drive (Getting Started) - FPGA.vi
item to open the VI.
3.
Select
Window»Show Block Diagram
to open the FPGA VI block diagram.
Fault Monitoring Loop
The Fault Monitoring loop sends fault information, including user-defined faults, to the
NI SoftMotion engine and sends the state machine implemented in the Control Status Loop into
a fault state. Figure 7 shows the Fault Monitoring Loop from the Stepper Drive (Getting Started)
example.
Figure 7.
Stepper Drive (Getting Started) Fault Monitoring Loop
Axis 1.Status Register
Contains information used to report status and operation
mode information from the device to the system.
Axis 1.Steps Generated
Returns the current step count of the stepper generator
taking into account the direction. This value is based on
actual steps generated, not feedback position, and may not
exactly match the feedback position.
1
Fault Code Array
2
Write Fault Drive Interface VI
Table 1.
Stepper Drive (Getting Started) UDV Descriptions (Continued)
UDV Name
Description
1
2
