I ran your code in the simulator with no h/w config and checked the diagnostic buffer for accesses to PIW/PQW1512, this led me to FC200. Each call to FC200 is passed a DB so I removed the calls until the PIW/PQW1512 accesses were no longer reported in the diagnostic buffer, this led me to DB310. I monitored DB310 online and there were only a couple of non-zero entries, this led me to DBD8 which I changed and the diagnostic buffer entry changed as well. QED.