Specifications

CP143 H1 / TCP/IP manual Network planning
Rev. 00/07 3-11
3.3.2 Regulations and specifications
Certain basic regulations must be observed when planning or installing a network:
• The cabling of a network consists of a number of segments. Both ends of each segment must be
terminated with its characteristic impedance (terminator) of 50 Ω.
• According to the ISO 8802.3 specification the maximum length of an individual segment is
500 m.
• Any segment may consist of a number of different parts. In this case you must ensure that the
length of each part is an odd multiple of 23,4 m to eliminate reflections at the joints and the ends
of any portion of the cable.
• The length of any part may thus be calculated as follows:
TSL = (2n + 1) * 23,4 m; N = 0, 1, 2, 3...
• Wherever possible, the network should consist of a homogeneous segments of coaxial cable as
every connector introduces losses. When it becomes necessary to extend existing segments of
coaxial cable you should always use standard portions of the cable. Please note that the
maximum length of a segment may not exceed 500 m.
• The screen of the coaxial cable may only be grounded at a single point on the entire cable. This
point must posses a defined low impedance. All other connectors and terminators must be
insulated from ground.
• Any two stations on the network may only have a single connection between them. Where
multiple physical paths exist the resulting interference will be interpreted as a signal and cause
collisions which may abort the data transfer.
• Single drop-cables are not permitted.