Technical data

The following connecting cables are permitted for the data rates listed:
☞
Make sure that at data rates 187.5 Kbps, 500 Kbps or 1500
Kbps the total length of the connecting cables does not
exceed 75 m, 30 m or 10 m respectively.
Cascading rules for repeaters
The permitted cascading depth depends on the data rate. At 1500 Kbps, a
maximum of four and at lower rates a maximum of seven repeaters can be
cascaded. A repeater causes a delay of approximately 1.5 bit times. This
delay time which is dependent on the data rate must also be taken into
account when calculating the slot time (refer also to Chapter 6).
Data rate Max. number of
connectable RS-485 bus
terminals with 1.5 m
connecting cables
Max. number of
connectable RS-485 bus
terminals with 3 m
connecting cables
9.6 Kbps 32 32
19.2 Kbps 32 32
93.75 Kbps 32 32
187.5 Kbps 32 25 *
500 Kbps 20 * 10 *
1500 Kbps 6 * 3 *
*These values apply to version 1 of the RS-485 bus terminal. On request, there is a
different version of the bus terminal which has no connecting cables, allowing a larger
number to be connected.
Table 2.2 Data Rate and Connecting Cables
System Overview B8976060/02
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