3 | Assembly
FISCHER Mess- und Regeltechnik GmbH
12 / 28
BA_EN_DE43
Supply circuit
BUS-D1
BUS-D0
BUS-R
DC
AC
BUS-D1
BUS-D0
BUS-R
U
b
+
U
b
-
1
3
2
4
5
DE43 Slave
Master
+
Fig. 14:
Supply
Please note that the M12 plugs are suitable for max. 2A. This value may
already be exceeded if there are more than 23 bus participants (without digital
inputs). For this reason, an intermediate feed should be provided at a suitable
place.
DE43
1
2
Address 24
DC
AC
2. Feed
1
2
E
DE43
1
2
Address 23
U
b1
U
b2
3
2
5
5
Modbus
∑
I
x
< 2 A
x=1
k
Fig. 15:
Intermediate supply
Please note that a DE43 with digital inputs has a higher power draw. If the bus
participants are equipped with digital inputs, the number of possible bus parti-
cipants of a supply circuit are reduced.
The power draw of a device x with n digital inputs is calculated as follows: I
x
=
55 mA + (n*4.5 mA)
This is calculated for the first bus participant and each of its successors. The
results are accumulated in sequence until the result exceeds the limit value 2 A.
The interim feed is then set after the bus participant k at which the total current
of the supply circuit last lay below 2 A.
