L-DALI User Manual 99 LOYTEC
Version 5.2 LOYTEC electronics GmbH
While status reflects the current state the device is in, the lost tokens counter is more
indicative for communication problems on the MS/TP network. If it increases, there are
cabling, ground, or termination issues.
Note, that the RX Port column monitors all packets seen on bus, not only those addressed
to the device. Statistics related to received packets that are addressed to the device are
tracked in the MS/TP State/RX column.
Figure 98: BACnet MS/TP Device Statistics.
The MS/TP Bus History (see Figure 99) presents information related to the MS/TP bus as a whole
over the last minute, split into 10 second time slices.
The convenient health indicator, a percentage in the range 0 – 100%, gives an overall
impression of the communication quality on the bus: The higher the percentage, the better
the MS/TP communication between devices on the bus. Reasons for health to be low are:
Superfluous PollForMaster requests (because MS/TP node addresses in use contain
gaps or Max_Master of the node with the largest node address is not set to the same
value as the node’s address),
token losses,
reply timeouts,
slow token passing.
The load percentage simply displays how much of the available bandwidth is used for data.
Note, however, that actual application data is only a subset of the amount of data taken into
account here.
Statistics reflecting the average ability of devices to initiate communication are roundtrip
and token/dev/sec. They give an impression on how long the token requires to circulate
once (in milliseconds), and how often a device on the bus receives the token per second.
Other counters of interest are: tk passes (the number of times the token was passed),
tk misses (the number of times the receiver of a token did not continue passing the token),
tk retry (the number of times passing of token was retried), postponed (the number of
ReplyPostPostponed packets seen), pfm (the number of PollForMaster packets seen),
data pkt, data pkt rx, data pkt tx (the number of data packets seen, the number of data
packets received and transmitted by the device), data, data rx, data tx (the amount of data
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