Rockwell Automation Allen-Bradley 1769-ASCII, Руководство пользователя

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Rockwell Automation Publication 1769-UM012B-EN-P - January 2014 105
Appendix
E
Using Electronic Keying
Electronic Keying The electronic keying feature automatically compares the expected module, as
shown in the Logix Designer I/O Configuration tree, to the physical module
before I/O communication begins. You can use electronic keying to help prevent
communication to a module that does not match the type and revision expected.
For each module in the I/O Configuration tree, the user-selected keying option
determines if, and how, an electronic keying check is performed. Typically, three
keying option are available:
•
Exact Match
•
Compatible Keying
•
Disable Keying
You must carefully consider the benefits and implications of each keying option
when selecting between them. For some specific module types, fewer options are
available.
Electronic keying is based on a set of attributes unique to each product revision.
When a Logix5000 controller begins communicating with a module, this set of
keying attributes is considered.
Topic Page
Electronic Keying 105
Exact Match 106
Compatible Keying 107
Disabled Keying 109
Table 15 - Keying Attributes
Attribute Description
Vendor The manufacturer of the module, for example, Rockwell Automation/Allen-Bradley.
Product Type The general type of the module, for example, communication adapter, AC drive, or digital I/O.
Product Code The specific type of module, generally represented by its catalog number, for example, 1756-IB16I.
Major Revision A number that represents the functional capabilities and data exchange formats of the module.
Typically, although not always, a later, that is higher, Major Revision supports at least all of the data
formats supported by an earlier, that is lower, Major Revision of the same catalog number and,
possibly, additional ones.
Minor Revision A number that indicates the module’s specific firmware revision. Minor Revisions typically do not
impact data compatibility but may indicate performance or behavior improvement.