21
Dat
e of
I
s
sue
04/
22/
2008
Par
t No.
194341
Optical data coupler LS611
Special notes on the use of several masters
second optical data coupler, the slot time parameter of the Class2-Master should be in-
creased by 100 bit.
Illustration 8.1
Two optical data couplers
8.1
Problem after light beam interruption in multi-master systems
Illustration 8.2
Light beam interruption in multi-master systems
After the light beam has been interrupted, a data collision may occur in multi-master sys-
tems, during the master of the control system retires for a short period of time. Depending
on the length of this condition, the entire bus does not operate correctly, which also af-
fects aisles (bus segments which operate downstream from an optical data coupler)
where the light beams have not been interrupted. This behavior is caused exclusively by
the Class2-Master of the opposite side. Light paths with exclusively passive stations on
the opposite side do not demonstrate such a behavior.
The bus segment which is directly connected up to the Class1-Master, is referred to as
being "stationary" here; bus segments which are located on the opposite side, "behind"
the optical data coupler, are referred to as "mobile" segments. At the same time the sta-
tionary side is to be the segment, from which several segments branch off to optical data
couplers (cf. illustration 8.3).
