Rockwell Automation 1785-Lxxx Enhanced and Ethernet PLC-5 Programmable Controllers - Manual (Page 144)

Publication 1785-UM012D-EN-P - July 2005
9-12 Communicating with Devices on a DH+ Link
Estimating DH+ Link
Performance Many factors affect the performance of your DH+ link, including:
• nodes
• size and number of messages
• message destination
• internal processing time
Linear scan failed 16 Number of times the station solicited every station number without getting a response. See
started linear scan below for more information.
Token retry 13 Number of times the station had to re-transmit a token pass. The station re-transmits a token
pass if it detects that the station it passed the token to did not receive the token. Noise can
cause this to occur.
Solicit rotations 34 Number of times a complete solicit successor of all stations not on the link is completed.
A solicit successor occurs during a token pass around the link. Here a station that is currently not
on the link is solicited to see if it has been added to the link. During each token pass, a different
station number is solicited; solicitation occurs sequentially. A station can only join the link when
it is solicited into it.
Started linear scan 15 Number of times the station has attempted to pass the token to everyone in its active node table
and no one has responded.
The station will then start a linear scan where it solicits every station number until a station
responds.
New successor 12 Number of times the station found a new successor for the token.
A new successor occurs when the station detects that a new station with a station number
between its and a the station it was passing the token to was added to the link. The station now
must past the token to the newly added station.
Token failed 14 Number of times station could not pass token to its listed successor. This usually occurs due to:
the station being removed from the network
noise or cabling problems
Status Field Word(s) Description