Siemens SIMATIC TIWAY 1 - Manual (Page 151)

HOST COMMAND SET REFERENCE
UNILINK HOST ADAPTER 5–66
USER MANUAL
eeee The number of TIWAY I HDLC errors, including command
rejects (FRMR), invalid HDLC responses, and sequence errors.
This number may reflect errors logged because a BROADCAST
NETWORK DATA TRANSFER command was issued. These
errors are logged because the POLL command is not available to
clear the outstanding frame.
ffff The total number of times the Network Manager changed to
another channel due to errors. This parameter will be zero if
redundant media is not available.