Rockwell Automation Publication 5069-UM002A-EN-P - January 2019 197
Develop Control Applications Chapter 8
Table 14 shows two data elements that are added to a structure for data
integrity checking. That is, Start Data and End Data are added. We
recommend that the controller validates the Start Data value and the End Data
value match before the controller acts on My_Recipe1.
If the Start Data and End Data values do not match, it is likely communications
is in the process of filling the structure. The same applies to higher-level
systems that are receiving data from the controller.
Produce and Consume
(Interlock) Data
CompactLogix 5480 controllers let you produce (transmit) and consume
(receive) controller-scoped tags.
Figure 39 - Example Produced and Consumed Tags
Table 14 - Data Elements
Structure My_Recipe1 My_Recipe2 My_Recipe3
Start Data 101 102 103
Sugar 3 4 8
Flour 4 3 9
Chocolate 2 2 4
Oil 6 7 2
End Data 101 102 103
TIP We recommend that you perform this test on a buffered copy of the data
and not the actual data element being written to by the communications
core. If you use buffered data, you prevent the risk of the communication
core changing data after you have passed the data valid test.
Controller_2
Controller_3
Controller_4
Consumed Tag
Consumed Tag
Consumed Tag
Controller_1
Produced Tag
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