KROHNE BM 70 A_P EN - Manual (Page 34)

Installation and operating instructions BM 70 A/P Page: 34 11/00
Ex-i Current output HART
®
with switching output: Current output (non-communicable):
Current-
output
Switching output
max. 110mA/30V
41 42 32 31
+ -
-
+
+ unit
U max.= 30V
4-20mA
U min.
= 8V
Ex-i-supply
32 31
Current
output
- +
unassigned
-
+
4-20mA
max.250
Ω
RS 485 version: PROFIBUS-PA or Foundation Fieldbus (FF)
B B A A
RS 485
input
RS 485
output
32 31
Current
output
- +
-
+
4-20mA
max.250 Ω
32 31
Bus-
connection
PROFIBUS-PA / FF with current output: PROFIBUS-PA / FF with switching output:
42
-
Ex-i-supply-
+
+ unit
+
U max.= 30V
current
output
4-20mA
U min.
= 8V
41
-
32 31
Bus-
connection
32 31
switching output
max. 110mA/30V
42 41
Bus-
connection
7.9 Terminating resistor for the RS 485 interface
A selector plug on the RS 485 board allows
optionally a high-resistance termination (presetting)
or a terminating resistor of 120
Ω
at the RS 485
connections A and B. For this purpose, the housing
(flameproof enclosure) of the BM 70 A/P signal con-
verter needs to be opened (see Sect. 9.3) and the
selector plug turned 180°, see sketch on the right.
120
Ω
RS485 signal-
output board
high-
impedance
....
....