Installation manual

Publication 1747-RM001G-EN-P - November 2008
13-16 SLC Communication Channels
General Network dead 5 Number of times the station detects no traffic on the network. This usually occurs when
the station with the token is powered down or is removed from the network. The other
stations are waiting for the token to be passed to them. Eventually a network dead
situation is declared and a claim token sequence is initiated. (See claims won for more
information.)
Claims won 6 Number of times the station has won the claim token sequence. All the stations
initiated a claim token sequence when a network goes down, is just powered up and the
stations on the network detect that no one has the token, or when a station with the
token is powered down or removed from the network. A claim token sequence is when
all the stations on a network attempt to claim the token. When multiple stations
attempt to claim the token, the lowest numbered station wins.
Claims lost 7 Number of times the station did not win the claim token sequence. See claims won for
more information.
New successor 8 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 retry 9 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.
Token failed 10 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.
Started linear scan 11 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.
Linear scan failed 12 Number of times the station solicited every station number without getting a response.
See started linear scan for more information.
Duplicate node 13 Number of times the station has detected the same station address as itself on the
network. As a result, the station goes offline.
Dropped token 14 Number of times that the station detected that a duplicate node existed on the link and
consequently dropped itself off the link.
A station determines that there is a duplicate node when it detects that the response to
a message or solicit successor is incorrect. For example, if a response is received from a
station which was not communicated with, then the sending station assumes that the
response is for a packet sent by another station with the same node number. Once the
station drops itself off the link, it waits indefinitely to be solicited back into the network.
It will only be solicited back into the network if the duplicate node is removed from the
link, because station numbers that already exist on the link are not solicited into the
network.
SDA/SDN
retransmissions
24 Total number of SDA or SDN messages that were re-transmitted. Some reasons why the
station would retry a message are:
• the ACK was lost or corrupted on an SDA message, indicating a possible noise
problem.
• the original message was NAKed.
Table 13.5 SLC 5/04 Channel 1 DH+ Channel Status (Continued)
Status field Word Displays the