37
NRG 26-61 - Installation & Operating Manual -
819874-00
Connecting the CAN bus system
Important notes on connecting the CAN bus system
■
■
A dedicated 24 V DC SELV power supply unit that is isolated from connected loads must be used to
supply the SPECTOR
connect system.
■
■
Make sure wiring is in line, not in a star!
■
■
Use a central earth to prevent differences in potential between plant parts.
■
◆
Connect the bus line shields to one another all the way along, and connect them to the central
earthing point (CEP).
■
■
If two or more system components are connected in a CAN bus network, a 120 Ω terminating resistor
must be connected to the
first
and
last
units between terminals C
L
/ C
H
.
■
■
Use the CAN bus connector with terminating resistor if you are using the level electrode as the first or
last unit.
■
■
Only
one
URS 60 and
one
URS 61 safety control unit may be used in the CAN bus network.
■
■
The CAN bus network must not be interrupted during operation!
If it is, an alarm is triggered.
Pin assignment of the CAN bus connector and coupling for non pre-wired
control cables
If non pre-wired control cables are used, you must wire the CAN bus connector and
couplings as shown in the wiring
Fig. 18
diagram.
1
S
Shield (screen)
2
+ 24 V
Power supply
3
− 0 V
Power supply
4
CH
CAN High data line
5
CL
CAN Low data line
1
2
3
4
5
1
2
3 4
5
Connector
Coupling
Fig. 18