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.
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 than represents the functional capabilities of a device. |
Minor Revision | A number that represents behavior changes in the device. |
The following 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 the following characteristics:
|
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 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. IMPORTANT: For safety I/O devices, do not use Disable Keying. |
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. |
Carefully consider the implications of each keying option when selecting one.
IMPORTANT:
When you change Electronic Keying parameters online, it 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.
For more detailed information on Electronic Keying, see Electronic Keying in Logix 5000 Control Systems Application Technique, publication LOGIX-AT001.
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