Allen-Bradley 1756-L63XT, User Manual

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84 Rockwell Automation Publication 1756-UM001O-EN-P - October 2014
Chapter 4 ControlLogix System and Controllers
Electronic Keying
Electronic Keying reduces the possibility that you use the wrong device in a
control system. It compares the device that is defined in your project to the
installed device. If keying fails, a fault occurs. These attributes are compared.
The following Electronic Keying options are available.
Carefully consider the implications of each keying option when selecting one.
More Information
For more detailed information on Electronic Keying, see Electronic Keying in
Logix5000 Control Systems Application Technique, publication
LOGIX-
AT001 .
Attribute Description
Vendor The device manufacturer.
Device Type The general type of the product, for example, digital I/O module.
Product Code The specific type of the product. The Product Code maps to a catalog number.
Major Revision A number that represents the functional capabilities of a device.
Minor Revision A number that represents behavior changes in the device.
Keying Option Description
Compatible
Module Lets the installed device accept the key of the device that is defined in the project when the
installed device can emulate the defined device. With Compatible Module, you can typically
replace a device with another device that has the following characteristics:
• Same catalog number
• Same or higher Major Revision
• Minor Revision as follows:
– If the Major Revision is the same, the Minor Revision must be the same or higher.
– If the Major Revision is higher, the Minor Revision can be any number.
Disable Keying Indicates that the keying attributes are not considered when attempting to communicate with a
device. With Disable Keying, communication can occur with a device other than the type specified
in the project.
ATTENTION : Be extremely cautious when using Disable Keying; if used incorrectly, this option can
lead to personal injury or death, property damage, or economic loss.
We
strongly recommend that you do not use Disable Keying.
If you use Disable Keying, you must take full responsibility for understanding whether the device
being used can fulfill the functional requirements of the application.
Exact Match Indicates that all keying attributes must match to establish communication. If any attribute does
not match precisely, communication with the device does not occur.
IMPORTANT
Changing Electronic Keying parameters online interrupts connections to the device and
any devices that are connected through the device. Connections from other controllers
can also be broken.
If an I/O connection to a device is interrupted, the result can be a loss of data.