HEIDENHAIN PROFINET - Manual (Page 15)

Installation
15
2 Installation
A summary of the PROFINET guideline: PROFINET Cabling and
interconnection Technology
V 1.99, PROFIBUS International, Order No 2.252 is provided in this
section.
2.1 Cables and standards
Two shielded copper cables twisted in pairs are defined as the
normal transmission medium for PROFINET networks. In such
networks the signal transmission is performed in accordance with
100BASE-TX at a transmission speed of 100 Mbps (Fast-
Ethernet).
Only shielded cables and connecting elements are allowed in a
PROFINET network. The individual components have to satisfy
the requirements of Category 5 in accordance with IEC 11801. The
entire transmission path has to meet the requirements of Class D
in accordance with IEC 11801. Furthermore, PROFINET cables
shall have a cable cross-section of AWG 22 in order to enable
even complex cabling structures through minimum damping. For
this reason, the specification of the PROFINET cables supports a
modular setup, which ensures an IEC 11801-compliant structure
on adherence to simple installation rules.
Transmission channels lengths are determined by the type of ca-
ble being used. The choice of cable is to be such that a transmis-
sion channel length of 100 meter is achieved between two active
network devices. The use of a high number of plug connections
has a negative effect on attenuation and reflection and conse-
quently reduces the transmission channel length. A maximum of
three interconnections can be inserted between two active de-
vices without reduction of the permissible transmission lengths of
100 meters.