Endress+Hauser prolevel FMC 661 - Rackbus RS-485 Option

2.5 Rackbus RS-485 option
Wiring the bus Up to 25 Prolevel FMC 661 transmitters can be connected to the Rackbus RS-485.
Instructions for wiring and grounding the bus are to be found in Operating Instructions
BA 134F which is delivered with Prolevel instruments having the Rackbus RS-485 option.
The Prolevel can be wired as indicated in the inset in Fig. 2.9.
Note!
• Terminal 61 is connected internally to the PE ground terminal strip
• The screening must be grounded and have electrical continuity throughout — read
BA 134F for grounding instructions
Bus address and
termination
Fig. 2.10 shows the configuration elements
for remote operation of the Prolevel
FMC 661. Every transmitter must have a
unique bus address:
• Switch off power, loosen screws and
open the terminal compartment
• Set the address at DIP-switch SW1
(Example: 2 + 8 = 10)
For the last transmitter on the bus, i.e.
furthest away from the computer:
• Switch in the terminal resistance at
DIP-switch SW2: OFF; ON; ON; OFF
• Close front panel, tighten screws.
A
L1
L2 (> L1)
Master
Rpull
Rt
Master
Rpull
Rt
1
OFF
ON
60 61 62
2
E
OFF
ON
OFF
ON
60 61 6260
61
62
1
OFF
ON
60
61
62
2
E
OFF
ON
OFF
ON
60
61
62
60
61
62
B
PE
PE
Rt
150Ω
Rt
150Ω
PE
PE
BA142_19/20
Fig. 2.9:
Rackbus RS-485 topologies
showing setting of bus
termination resistance
Inset:
Suggestion for wiring the bus
SW1
12481632
150Ω 392Ω392Ω
+5V
(=10)
ON
OFF
ON
OFF
RS-485
[EExia]IIC
B DGND A
L+ L-
L1 N
1b1a 2a 2b
- +
- +
SW2
BA142_21
bus termination
switch
address switch
terminal compartment
Fig. 2.10:
DIP-switches for bus address and termination
61
PE
60 62
Data B
Data A
Screen
Note!
Chapter 2: Installation Prolevel FMC 661
18 Endress+Hauser