S7-400 FB125 DB125 DP Diagnostics question

Hi,

I'm using the old Siemens DP diagnostic blocks FB125/DB125 in a 20 year old S7-400 and I can't fing any documentation to tell me why the counters at DB address DBB1272 onwards would count.

I have 6x Lenze 8400 drives connected on profibus and every one of them has a count value, but the _MEM (DB125.DW1256) bits are all OFF, suggesting there's been no faults.

So does anybody know why the counters DBB1272+n would count?

PS I'm using both PZD and PAR modules in the HW config.

Thanks