BECKHOFF EtherCAT Technology Section I - Manual (Page 77)

Distributed Clocks
Slave Controller – Technology I-57
The System Time Difference Filter Depth register (0x0934) and the Speed Counter Filter Depth
register (0x0935) set filter depths for mean value calculation of the received System Times and of the
calculated clock period deviations.
Registers used for Control Loop/Drift Compensation are listed in Table 29.
Table 29: Registers for Drift Compensation
Register Address Name Description
0x0900:0x090F Receive Time Port n Local time when receiving frame on Port n
0x0918:0x091F Receive Time ECAT
Processing Unit Local time when receiving frame for ECAT
Processing Unit
0x0910:0x0917 System Time Local copy of System Time (read from PDI)
(local time if System Time Offset=0)
0x0920:0x0927 System Time Offset Time difference between System Time and
local time
0x0928:0x092B System Time Delay Delay between Reference Clock and the
ESC
0x092C:0x092F System Time Difference
Mean difference between local copy of
System Time and received System Time
values
0x0930:0x0931 Speed Counter Start
Bandwidth for adjustment of local copy of
System Time
0x0932:0x0933 Speed Counter Diff
Deviation between local clock period and
Reference Clock’s clock period
0x0934
System Time Difference Filter
Depth Filter depth for averaging the received
System Time deviation
0x0935 Speed Counter Filter Depth
Filter depth for averaging the clock period
deviation