E+H-Rackbus and Rackbus RS 485 wiring
Warning!
When connecting flowmeters with Ex approval, all appropriate instructions and
connections diagrams in the seperate Ex documentation to this Operating Manual
must be observed.
1. Wire up according to Figure 32.
The bus is connected using the FXA 675 assembly module or the Commubox
FXA 192 (see Fig. 30, 31), which are galvanically isolated.
Cable specifications for Rackbus RS 485:
• Connection cable: two-core, twisted, screened
• Conductor cross-section / cable diameter: ≥ 0.20 mm
2
(24 AWG)
cable length: max. 1200 m (3900 ft)
2. Set terminating resistors if necessary (see Fig. 33)
Normally, the corresponding selection switches on the communications board
may be left in the factory setting position (all switches = OFF).
3. Subsequent to the bus installation, the following functions of the operating matrix
have to be set (see page 69):
• PROTOCOL → Select “RACKBUS RS 485” protocol (factory setting = OFF)
• BUS ADDRESS → Set bus address for the respective transmitter (0...63)
Warning!
u
u
u
Commubox FXA 192
Personal computer with
“Commuwin II” program and
with a ZA 672-DDE server
Rackbus
RS 485
Direct connection to a PC
ba009y77
Fig. 31
Direct PC connection to
Rackbus RS 485 via
Commubox FXA 192
Promag 33 4 Electrical Connection
Endress+Hauser 31
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