Siemens SIMATIC NET PROFIBUS manual Segments for Transmission Rates up to a Maximum of 12 Mbps

Configuring Networks

3.1.3Segments for Transmission Rates up to a Maximum of 12 Mbps

Transmission Rate up to a Maximum of 12 Mbps

Table 3-6 Possible Segment Lengths

		Segment Length for Cable Type
Transmission Rate	– FC Standard Cable		– FC Trailing Cable
	– FC Robust Cable		– PROFIBUS Flexible Cable
in Mbps
	– FC FRNC Cable		– PROFIBUS Festoon Cable
	– FC Food Cable
	– FC Underground Cable
	– SIENOPYR–FR Marine Cable
3	100 m		100 m
6	100 m		100 m
12	100 m		100 m

When planning segments for transmission rates from 3 Mbps to a maximum of 12 Mbps, the following factors must be taken into account:

STo attach DTEs to bus segments, only the bus connectors permitted for 12 Mbps or the BT12M bus terminal can be used.

SThe maximum length of a segment must not exceed 100 m.

SThe maximum number of bus attachments (nodes, OLMs, RS-485 repeaters,...) in one segment is restricted to 32.

STo attach a programming device or PC via a tap line, only the “SIMATIC S5/S7 connecting cable, 12 Mbps, order no. 6ES7901-4BD00-0XA0” can be used.

Note

If several bus connectors are used at electrically short distances (in other words, the cable length between adjacent connectors is less than 1 m) (for example, several slaves in one cubicle), avoid disconnecting several bus connectors at the same time for longer periods. Disconnecting more than one bus connector does not necessarily mean errors but may well reduce the reliability (immunity to noise) of a segment.

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	6GK1970-5CA20-0AA1 Release 2 05/2000