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Why, in the Safe part of M580 Safety PLC logic with Control Expert V15.0, does the output link of an Elementary Function (EF) remains enabled

Question:
Why in the Safe part of M580 Safety PLC logic with Control Expert V15.0, does the output link of an Elementary Function (EF) remains enabled when:
•   the EN input is disabled (EN=0)
•   the project setting “maintain output links on disabled EF (EN=0)” is not checked

Figure 1: Example of the issue impacting the logic (when project setting "maintain output links on disabled EF (EN=0)” is not checked)

Answer:

1. Issue
When the EN input of the safety EF is disabled (EN =0), its output link keeps its previous value even if it should be set to 0 as per the project settings.
This unexpected behavior only impacts the safety logic (in the SAFE task). The process logic (in the MAST or FAST task) is not impacted.

2. Product Line
M580 Safety Processors BME•58••••S programmed with Control Expert V15.0

3. Resolution
We recommend programming safety logic in a way that the safety logic does not depend on the project setting (output links of disabled EF should not be used in an enabled logic).

Temporary workaround :
-   We propose to insert a "S_SEL" function block between the output of the EF function block using EN pin and the destination logic of the link as shown in the example below (figure2) to fix the issue in the logic of the figure 1 :

Figure 2: example of workaround to avoid the logic to be impacted by the issue based on logic from figure 1

Fix
A hotfix "ControlExpert_V150_HF0380584E_B"for Control Expert V15.0 has been provided to get back to the normal behavior : https://www.se.com/ww/en/download/document/ControlExpert_V15_HF0380584E_B/

This Hotfix is also integrated in official next Control Expert release starting from Control Expert V15.0 SP1 : https://www.se.com/ww/en/download/document/EcoStruxureControlExpert_15SP1/

Once the hotfix is installed (or V15.0 SP1 release), a rebuild all of the application must be performed.
Output links will be maintained or set to 0 on a deactivated EF, as per the chosen project setting “maintain output links on disabled EF (EN=0)”.

Here is a screenshot of the flyer that will be part of the safety digital license :

Additionnal note : in case you applied Hotfix "ControlExpert_V150_HF0380584E", in case you are using M340 platform, please check FAQ000207826 : https://www.se.com/us/en/faqs/FAQ000207826/