I did not try to test FC17 function ( other FC in 840D PL tested most of them). for 840D SL may be the same as 840D PL. I check 840D Function description .  Apparently you read the Siemens manual of this section. But I am not sure --did you find the last words --see attached picture. do you think that si meaning --you need use PLC program to make enable/disable by yourself? 

AutoGen_476886

Dear all,

840DSL system, version 4.7, I want to commissioning Star-Delta change using FC17, but when I give the change condition, the output can't change. The attachment picture shows one step is the internal pulses shut down automatically, but in my commissioning it can't. And then I manually switch off enable and switch on, the FC17 output changes, from Star to Delta. So I want to know where is the setting that can let system shut down the pulses internally not as I manually. Thanks!

I did not (as I said) make deep search for FC17, but I know it is possible even Siemens documentation some missing message or mistakes. I think you have ability to add PLC program to make the missing function. if it works, welcome to share 

PS: I have made some modification to FC19 ( add more parameters) for 840D PL in 1999. and shared in Siemens China. Actually I tried to test all FC's FB's in 840D PL, except FC17.