Appendix A
DeviceNet Overview
A-12
ni.com
Figure A-6.
Input and Output Assemblies
As a more specific example, consider a DeviceNet photoelectric sensor
(photoeye) or a limit switch. These devices contain a single instance of a
class called the Presence Sensing object. This instance has attributes for the
Output Signal (on/off) and Diagnostic Status (good/fault). These two
attributes are often routed through a single input assembly consisting of a
single byte.
Figure A-7 shows an example of a Presence Sensing instance and its input
assembly.
Figure A-7.
Input Assembly for Photoeye or Limit Switch
Attributes
Instance
Attributes
Instance
Attributes
Instance
Output Assembly, Associated
with an Output Message
Such as a Poll Command
Input Assembly, Associated
with an Input Message
Such as a Poll Response
0
0
0
Operate Mode, BOOL
0
0
0
7
Bit
6
5
1
0
4
3
2
Diagnostic, BOOL
Off Delay, UINT
On Delay, UINT
Output, BOOL
Attributes
Presence Sensor Instance 1
One byte input assembly,
often returned as a strobe
response or COS input message.
