Electronic Keying

Electronic Keying reduces the possibility of using the wrong device in a control system. It compares the device defined in your project to the installed device. If keying fails, a fault occurs.
For more detailed information on Electronic Keying, see Electronic Keying in
Logix5000
 Control Systems Application Technique, publication LOGIX-AT001.
Electronic Keying compares these attributes:
Attribute
Description
Vendor
The device manufacturer.
Device Type
The general type of the device, for example, digital I/O device.
Product Code
The specific type of device. 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.
These Electronic Keying options are available:
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 these 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.
WARNING:
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.
Consider the implications of each keying option when selecting one.
IMPORTANT:
Changing Electronic Keying parameters online interrupts connections to the device and any devices connected through the device. It also breaks connections from other controllers.
Interrupting an I/O connection to a device might result in a loss of data.
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