Generating an Instruction Signature
The instruction signature consists of an ID number, and date/timestamp that identifies the contents of the Add-On Instruction at a given point in time. Once generated, the instruction signature seals the Add-On Instruction, preventing it from being edited. This includes rung comments, tag descriptions, and any instruction documentation that was created. When an instruction is sealed, you can only copy the instruction signature, create a signature history entry, download the instruction, print or remove the instruction signature.
The instruction signature is checked at each download to verify that the Add-On Instruction parameters, local tags, and logic are unchanged. When the instruction signature has been generated, the Logix Designer application displays the instruction with a blue seal icon, as shown here:
In addition, when a safety Add-On Instruction has been sealed with an instruction signature, a safety instruction signature ID is automatically generated when the safety Add-On Instruction is downloaded for the first time (and verified each subsequent download).
For information about certifying a safety Add-On Instruction, see the GuardLogix 5580 and Compact GuardLogix 5380 Controller Systems Safety Reference, publication 1756-RM012.
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If you want to allow language switching on an Add-On Instruction that will be sealed, you must enter the localized documentation information into your Add-On Instruction before generating the signature. The signature history is created after the signature is generated, so the signature history is not translatable in the Logix Designer application. If the translated information already exists in the sealed Add-On Instruction, you can switch the language with the seal (signature) intact. This is because the switch does not alter the Add-On Instruction; it only changes the displayed language.
Follow these steps to generate an instruction signature:
- Note the following.
- You must be offline to perform this procedure. The button is enabled only when offline.
- If this is a safety Add-On Instruction, the project cannot be safety-locked or have a safety task signature.
- Signatures only apply to a top-level Add-On Instruction. Any referenced Add-On Instructions must be sealed separately.
- An instruction can be sealed whether it is verified or not. It does not depend on the verify status of the Add-On Instruction.
- To generate an Add-On Instruction signature, click the Generate button on the Signature tab.
- Answer Yes to the prompt "Generate instruction signature?" Note the following:
- Selecting Yes seals the instruction, generates its signature, updates the Last Edit Date, and places the instruction in a read-only state to prevent edits.
- If unsaved edits exist on other tabs of the Add-On Instruction dialog box, the prompt reads as follows: "Unapplied edits exist in the add-on instruction. Do you want to apply edits and generate signature?" Answering Yes saves those edits and generates a signature.
- Selecting No cancels the operation with no action taken.
- Click the Add to History button if you want to add an entry to the signature history table.
- Click OK and save the project.IMPORTANT: The Generate signature action is lost (with all unsaved edits) if the project is not saved.
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