KROHNE BM 70 A Installation And Operating Instructions Manual page 12

Transmission rate:
Address:
Protocols:
V.3.02/4.02)
Additional current output:
Note:
Various bus configurations
A) Connection of a BM 70 A/P as a single RS 485 user:
Bus line (2 shielded wires)
Computer
system
RS485 connection must
be terminated with 120 ohms
(if necessary insert resistor
between A and B)
B) Connection of several BM 70 A/P in the RS 485 bus system via stubs to the bus cable:
Computer
system
RS485 connection must
be terminated with 120 ohms
(if necessary insert resistor
between A and B)
C) Connection of several BM 70 A/P in the RS 485 bus system, with bus cable looped through to
further field instruments:
Computer
system
RS485 connection must
be terminated with 120 ohms
(if necessary insert resistor
between A and B)
Notes:
• If other devices are operated together with the BM 70 A/P Level-Radar on one bus, all devices
must use the same Communications protocol (e.g. ModBus devices of different makes or BM 70
A/P and TTM 70 with KROHNE Protocol).
• When "HART ®
" is set as the protocol type, use only the protocol in keeping with the "HART
Specification". The "Hardware Implementation RS 485" does not conform to the HART
(see Sections 4.2 and 4.3).
Installation and operating instructions BM 70 A/P
1200 to 38400 bauds
0 to 255
KROHNE Protocol, HART
Additional information: see "BM 70 A/P Communication RS 485"
instructions
The current output is conductively coupled to the RS 485 interface.
Technical data: see Section 4.5
Switching contact and digital input are not available. However, the
current output can be configured as a switching output.
with termination
resistance
120 ohms
Bus line (2 shielded wires)
...........
without without
termination termination
resistance resistance
Bus line (2 shielded wires)
...........
without without
termination termination
resistance resistance
®
, Modbus RTU
without with termination
termination resistance
resistance 120 ohms
without with termination
termination resistance
resistance 120 ohms
Page: 12
(from firmware
®
®
Standard
11/00