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By consulting the specifications for the Control Supervisor object and the 
AC/DC Drive object, you can determine that the DeviceNet data type for 
Run Fwd and Fault Reset is 

BOOL

 (boolean), and the DeviceNet data type 

for Speed Reference is 

INT

 (16-bit signed integer).

Many fundamental differences exist between the encoding of a DeviceNet 
data type and its equivalent data type in LabVIEW. For example, for a 
32-bit integer, the DeviceNet 

DINT

 data type uses Intel byte ordering 

(lowest byte first), and the equivalent LabVIEW 

I32

 data type uses 

Motorola byte ordering (highest byte first).

To make it easier for you to avoid these data type issues in your 
LabVIEW application, NI-DNET provides two functions to convert 
between LabVIEW data types and DeviceNet data types: 

ncConvertForDnetWrite

 and 

ncConvertFromDnetRead

. These 

functions are used to access individual members of an I/O assembly using 
normal LabVIEW controls and indicators.

The following steps show an example of how you can use 

ncConvertForDnetWrite

 to access the Basic Speed Control Output 

Assembly described in the previous section:

1.

Use the NI-DNET palette to place 

ncConvertForDnetWrite

 into 

your diagram.

2.

Right-click on the 

DnetData in

 terminal and select Create 

Constant, then initialize the first 4 bytes of the array to zero.

3.

Right-click on the 

DnetType

 terminal and select Create Constant, 

then select 

BOOL

 from the enumeration.

Table 4-1.  Attribute Mapping for Basic Speed Control Output Assembly

Run Fwd

Control 
Supervisor

29 hex

1

Run1

3

Fault 
Reset

Control 
Supervisor

29 hex

1

FaultRst

12

Speed 
Reference

AC/DC 
Drive

2A hex

1

SpeedRef

8