Bender ISOSCAN W Series - Device Communication; RS-485 Interface; Bender Sensor Bus (BS Bus)

ISOSCAN® EDS440 and EDS441
7 Device communication
7.1 RS-485 interface
The RS-485 interface is galvanically isolated from the unit electronics. It serves as a transmission medium for
various protocols. It can be used to connect ISOMETER® and compatible devices to an RS-485 network.
Specification
cable length max. 1200 m
branch line max. 1 m
cable type twisted-pair (e.g. J-Y(St)Y n × 2 × 0.8), shield single-ended connection to earth
number of devices restricted by bus master
topology linear (daisy chain)
termination first and last device via
•
terminating switch on device or
•
resistor (120 Ω, 0,25 W) between termninals A and B
Line structure
B
A
B
A
B
A
B
A
max.
1 m
max. 1200 m
120 Ω
120 Ω
1. Device 2. Device x. Device Last Device
Examples for RS-485 line structures
1
2
2
2
3
1
2
2
2
2 2 2
3
1 2 2
2
3
1 Master with termination
2 Slave without termination
3 Slave with termination
ADVICE
An RS-485 network that is not terminated may become unstable and generate malfunctions. Only the
first and last device in the line may be terminated.
Branch lines must not be terminated. Their length is limited to max. 1 m.
7.2 Bender Sensor bus (BS bus)
The BS bus serves to add further Bender measuring devices (e.g. ISOMETER®). It is an RS-485 interface with a
protocol especially developed for Bender devices. On the BS bus the transmission of alarm messages takes
priority over the transmission of all other messages. For further information, refer to the BS bus manual
(document number: D00278) under www.bender.de/service-support/downloadbereich.
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