Update your settings

Dear experts,
I have a problem using SFC13 function which I want to use to read out diagnostic data from ET200S modules. CPU is 414-2DP and it is connected to ET200S modules (18 of them) by PROFIBUS.
In OB35 (100ms) I created request for SFC13 (request input of function) and loaded LADDR parameter as diagnostic address for specific ET200S module. My idea was to, every 100ms, send request to SFC13 (it is called in OB1) with different diagnostic address so I would, in two seconds, go through all modules to check if there were some problems in modules.
This was all working for some time - few months - but now it doesn't work anymore. I went online and saw that BUSY output of function SFC13 was newer active and on RET_VAL output two numbers were changing - W#16#7000 and W#16#80C3. What do those errors mean?
I saw somewhere that there is a limit of simultaneous SFC13 functions calls according to CPU type but I call this function only once - only one instance is active but every 100ms I call it.
I put the same software in another machine today and for now it works perfectly. Is there any other limitation for using SFC13?
Thanks in advance!