Network Design Considerations 2-9
SIMATIC TIWAY I Series 500 NIM User Manual
Local Line Cable Installation (continued)
As shown in Figure 2-2, when you use Belden 9860 cable (or its
equivalent), up to 75 stations can be attached to a network operating at 38K
bps and having a spine length of 20,000 feet. At 115.2K bps, the maximum
length of a Local Line network having 254 stations is 10,000 feet.
The Local Line primarily consists of two items:
•Twisted-pair cabling
•Tap housings
Siemens recommends Belden 9860 twisted pair cabling, or its equivalent,
for use as the Local Line network spine. Belden 9271, or its equivalent,
should be used for the dropline. Brands other than those listed here will be
specified by Siemens upon request.
The tap housing, shown in Figure 2-3, is made by Siemens specifically for
its Local Line network. The tap housing can be mounted rigidly to a NEMA
panel or other enclosure. It could also be used to splice cables in a cable tray
without being rigidly mounted. The tap housing not only allows an orderly
connection to the TIWAY I network, but also contains terminating resistors,
resists moisture, relieves strain, and provides noise isolation for attached
cabling.
Tap housings are included for each Local Line port; however, extras may be
ordered from your distributor. Order part number PPX:500–5606.
Local Line Tap
Housings