Electronic Keying

Electronic Keying reduces the possibility of using the wrong device in a control system. Electronic Keying compares the device defined in the project to the installed device. If keying fails, a fault occurs.
These attributes are compared:
Attributes used in Electronic Keying validation
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:
Electronic Keying options
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. Typically, use Compatible Module to replace a device with another device that has these characteristics:
  • Same catalog number
  • Same or higher major revision
  • Minor revision:
    • 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.
CAUTION:
Use extreme caution when using Disable Keying. If used incorrectly, this option can lead to personal injury or death, property damage, or economic loss.
We strongly recommend not using Disable Keying.
If using Disable Keying, 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.
  • A loss of data may occur if an I/O connection to a device is interrupted.
For detailed information on Electronic Keying, see Electronic Keying in Logix5000 Control Systems Application Technique, publication LOGIX-AT001.
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