Rockwell-automation 1769-ASCII Compact I/O ASCII Module Manuel d'utilisateur télécharger pdf (Page 109)

Rockwell Automation Publication 1769-UM012B-EN-P - January 2014 109

Using Electronic Keying Appendix E

Disabled Keying

Disabled Keying indicates the keying attributes are not considered when

attempting to communicate with a module. Other attributes, such as data size

and format, are considered and must be acceptable before I/O communication is

established. With Disabled Keying, I/O communication may occur with a

module other than the type specified in the I/O Configuration tree with

unpredictable results. We generally do not recommend using Disabled Keying.

EXAMPLE

In the following scenario, Compatible Keying allows I/O communication:

The module configuration is for a 1756-IB16D module with module revision

2.1. The physical module is a 1756-IB16D module with module revision 3.2. In

this case, communication is allowed because the major revision of the physical

module is higher than expected and the module determines that it is

compatible with the prior major revision.

IMPORTANT

Changing electronic keying selections online may cause the I/O

communication connection to the module to be disrupted and may result in

a loss of data.

Module Configuration

Vendor = Allen-Bradley

Product Type = Digital Input Module

Catalog Number = 1756-IB16D

Major Revision = 2

Minor Revision = 1

Physical Module

Vendor = Allen-Bradley

Product Type = Digital Input Module

Catalog Number = 1756-IB16D

Major Revision = 3

Minor Revision = 2

Communication is allowed.

ATTENTION: Be extremely cautious when using Disabled Keying; if used

incorrectly, this option can lead to personal injury or death, property

damage, or economic loss.

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Rockwell-automation 1769-ASCII Compact I/O ASCII Module Manuel d'utilisateur Page 109