Today I was working on building a graphic for all simulation alarms. By default, the PCSD AI class has a Simulation alarm that is tied to the block error with the correct mask. The only bit that is enabled to alarm on is the Simulate Active everything else is unchecked. What I keep running into is that some/probably majority of modules linked to this class (maybe in the 1000s). Are coming up with an Active alarm of simulation. It's like it no picking up the mask from the class. I exported the module and reviewed the FHX and for the class-based module the mask was 4096 meaning 12 bit is on. So, everything is configured correctly. I downloaded the module did nothing. What I found is that even though the class is only looking for bit 12 (simulate active) the class base module has everything checked. For example, the module I was working was showing that the bad input flag was causing block error and then was driving my simulation alarm to active. The next test I did was make the module classless and see what the mask would go to. When I did that the Alarm mask showed that all bits would trigger the alarm. So, then I unchecked everything but simulation active and relinked it to the AI class and it fixed it. My question has anyone dealt with this I know my work around, but I would have to do this for ALOT of modules not feasible. The other work around still a lot of work would make a CND block that only looks at the Simulation Active bit and connect to a parameter name "simulated" and drive the alarm based on simulate.