BECKHOFF EtherCAT Registers Section II - Manual (Page 78)

Distributed Clocks (0x0900:0x09FF)
II-66 Slave Controller – Register Description
Table 108: Register Receive Time Latch Mode (0x0936)
ESC20 ET1100 ET1200 IP Core
Bit Description ECAT PDI Reset Value
0 Receive Time Latch Mode:
0:
Forwarding mode (used if frames are
entering the ESC at port 0 first):
Receive time stamps of ports 1-3 are
enabled after the write access to
0x0900, so the following frame at ports
1-3 will be time stamped (this is typically
the write frame to 0x0900 coming back
from the network behind the ESC).
1: Reverse mode (used if frames are
entering ESC at port 1-3 first):
Receive time stamps of ports 1-3 are
immediately taken over from the internal
hidden time stamp registers, so the
previous frame entering the ESC at
ports 1-3 will be time stamped when the
write frame to 0x0900 enters port 0 (the
previous frame at ports 1-3 is typically
the write frame to 0x0900 coming from
the master, which will enable time
stamping at the ESC once it enters port
0).
r/w r/- 0
7:1 Reserved r/- r/- 0
NOTE: There should not be frames traveling around the network before and after the time stamps are taken,
otherwise these frames might get time stamped, and not the write frame to 0x0900.