We have using LOGO without display LOGO V8.3 (6ED1052-2MD08-0BA1) PLC with FW Version 1.83.02 with TDE display (6ED1055-4MHO8-0BA1) of FW Version in TDEdisplay1.83.01. In this we have worked on Function Block. for message text switching we have used M27 for showing the message difference still now in V8.3 all are working good and acknowledging the message without any error on Both M27 in OFF or ON state.  

But, Now the new version is LOGO V8.4 (6ED1052-2MD08-0BA2) PLC with FW Version 1.84.02 is we can’t acknowledge the alarms in TDE display with the FW Version in TDE display1.83.01. When the M27 is in ON state. We were able to acknowledging all messages in M27 is in OFF state but we can’t acknowledge in M27 in ON state.

As we checked the PLC (6ED1052-2MD08-0BA2)  and TDE display (6ED1055-4MHO8-0BA1), in simulation all functions acknowledging without any error. And once download in PLC and TDE the above mentioned error occurs. We have Enabled all the BM setting in both TDE and PLC.

And I have attached the mention error with an Program.

Input 1 used for M27 bit enable and disable.

Input 2 used for Message Enabled.

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Split from LOGO! Message Texts - How to sequence them?.

Topic closed because the question has been posted twice. The active topic can be found here:

M27 FB Bit Issues in V8.4

Kind regards, Moderator_Lan