Cable Lengths - Siemens SIMATIC C7-626 Installation, Assembly, Wiring

Configuring MPI Networks and PROFIBUS-DP Networks
3.3

Cable Lengths

Segment in an MPI
Network
3
Segment in a
PROFIBUS-DP
Network
Longer Cable
Lengths
3-12
You can implement cable lengths up to 50 m in a segment of an MPI
network. The 50 m applies from the first node to the last node of the
segment.
Table 3-2 Permissible Cable Length of a Segment in an MPI Network
Transmission Rate
187.5 Kbps
*with non-isolated interface
In a segment of a PROFIBUS-DP network, the cable length depends on the
transmission rate (see Table 3-3).
Table 3-3 Permissible Cable Length of a Segment in a PROFIBUS-DP Network
Depending on the Transmission Rate
Transmission Rate
9.6 to 187.5 Kbps
500 Kbps
1.5 Mbps
3 to 12 Mbps
*with isolated interface
If you implement longer cable lengths than those permissible in one segment,
you must use RS 485 repeaters. The maximum possible lengths between two
RS 485 repeaters correspond to the cable length of a segment. However,
when using these maximum cable lengths, note that there must be no other
node (remote segment) between the two RS 485 repeaters. You can connect
up to nine RS 485 repeaters in series.
When calculating the total number of nodes to be connected, note that an
RS 485 repeater counts as a node of the network, even if it has not been
assigned its own MPI/L2 address.
Figure 3-8 illustrates the principle of "cable extension" with RS 485
repeaters for the MPI.
Max. Cable Length of a Segment
(in m)
50
*
Max. Cable Length of a Segment
(in m)
1000
*
400
200
100
C7-626 / C7-626 DP Control Systems
C79000-G7076-C626-01