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National Instruments Corporation
19
NI 9144 User Guide and Specifications
Appendix A
Vendor Extensions to the Object Dictionary
Most object dictionary entries are defined by the relevant EtherCAT and
CANOpen specification for modular slave devices. Both the NI 9144
device and the C Series modules have vendor extensions to the standard.
These extensions are described here.
Note
Most object dictionary entries are set to usable defaults during the NI 9144’s
transition from INIT to PREOP. NI recommends writing down the object dictionary default
values, in case you need to revert to them, before you begin to overwrite them with new
values prior to the transition to SAFEOP.
Note
The following lists the most common C Series module vendor extensions. Each
module has its own extensions which may vary from the information listed here, and any
given object dictionary index may have a different meaning depending on which module is
inserted. For more information, refer to your C Series module documentation.
Table 3 lists common module vendor extensions.
Table 3.
Module Vendor Extensions
Index
Sub
Type
R/W
Description
NI 9144 Vendor Extension
0x3001
0
ARR:U32
—
Timing Overrides: provides additional control over the
timing of the NI 9144
—
1
—
R/W
Minimum free-run cycle time in nanoseconds. Set to 0
to operate at the minimum cycle. Set to 1,000,000 for
a 1 mS cycle (1 kHz).
—
2
—
R/W
Disables multiple scans. Setting the field to 1 disables
multiple-scan ability. Even when a module has enough
time during the cycle to acquire more than one set of
data, only one acquisition occurs. This is useful when
analyzing the module acquisition timing.
0x5FFF
0
U32
R/W
Slot address override. To address CoE requests to a
given module’s object dictionary, write the module’s
slot number here. Write a 0 here to cancel the slot
address override.
