24 Annex
390
Bus cabling in line topology
In the line topology, the bus line must be provided with terminating resistors at
both ends wherever possible, in order to avoid transmission interference
through reflections. If JUMO ecoLine sensors are used, however, terminating re-
sistors must not be employed. You should therefore use terminating resistors
only in a JUMO digiLine bus without JUMO ecoLine sensors. M12 terminating
connectors are available from JUMO for the bus termination.
⇨ Chapter 4.4 "Accessories", page 25
Terminating resistors can be activated via DIP switch on the options board for
serial interface RS422/485.
⇨ Chapter "Optional board interfaces", page 64
Sensor type Max. length of
bus line
a
Max. length of
stub lines
b
Max. number of con-
nectable sensors
Comment
JUMO digiLine pH/
ORP/T
100 m 10 m 6 max. admissible
voltage drop be-
tween DC 5 V
supply and the
last sensor:
1.0 V
JUMO ecoLine O-DO
JUMO ecoLine NTU
100 m 10 m 6 Bus termination
not admissible;
max. admissible
voltage drop be-
tween DC 5 V
supply and the
last sensor:
0.3 V
a
The maximum length of the bus line depends on the number and type of connected sensors and on how
they are distributed along the bus line. Due to the widely varying current consumptions of the different
sensor types, it is difficult to state a generate value that will apply for all installation situations. In case of
doubt, it is advisable to carry out a voltage drop calculation during the planning phase (cf. Chapter 24.2.4
"Voltage drop calculation", page 396).
b
Stub line from a JUMO digiLine hub or Y-distributor up to a sensor with JUMO digiLine electronics
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