Siemens SIMATIC NET PROFIBUS Owner's Manual page 44

Topologies of SIMATIC NET PROFIBUS Networks
DP/PA coupler Ex [i]
6ES7 157-0AD00-0XA0
Protection EEx [ia] II C
x 90 mA
I
max
DP/PA coupler Ex [i]
6ES7 157-0AD80-0XA0
Protection EEx [ib] II C
x 110 mA
I
max
DP/PA coupler
6ES7 157-0ACx0-0XA0
x 400 mA
I
max
Figure 2-12 Field Device Power Supply in the Hazardous and Non-Hazardous Area
Expansion
If the maximum output current of the DP/PA coupler is exceeded, you must include
a further DP/PA coupler.
Total Cable
The total cable is the total of the main cable and all the tap lines.
When using a standard PROFIBUS-PA cable with a cross-sectional area of
2
0.8 mm , the maximum length of the total cable (with a maximum number of field
devices and worst-case positioning at the end of the cable) is as follows:
S 560 m for DP/PA coupler (6ES7 157-0AC00-0XA0)
S 680 m for DP/PA coupler (6ES7 157-0AD80-0XA0)
S 790 m for DP/PA coupler Ex [i] (6ES7 157-0AD00-0XA0)
Tap Line
The maximum permitted tap line lengths are listed in Table 2-2. You should also
remember the maximum length of the total cable (see above).
2-18
PROFIBUS-PA
I
I
max
1
Field device
1
24 V DC
PROFIBUS-DP
PROFIBUS-PA
I
I
max
1
Field device
1
24 V DC
PROFIBUS-DP
I ...I
I
3...
2
Field device Field device
2
3...
Explosion-protected area
I ...I
I
3...
2
Field device Field device
2
3...
PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000
n
Field device
...n
m
Field device
...m