GE Industrial Solutions AF-600 FP BACnet - Manual (Page 12)

3.1.2 Cabling
Cable lengths and number of nodes
The maximum cable length allowable in one segment is dependent on the transmission speed. The total cable length includes drop cables if any. A drop cable is
the connection from the main bus cable to each node if a T-connection is used instead of permissible cable length and maximum number of nodes/Drivess with
1, 2, 3 and 4 bus segments.
Drop cable connection (i.e. T-connection) beyond the cable lengths indicated is not recommended, due to the increased risk of reflection occurring. Instead, GE
recommends direct connection of the drive.
Note that a repeater is a node in both of the two segments it connects. The number of frequency converters is based on a single master system. If there are two
or more masters (e.g. PC tools, Routers), the number of frequency converters must be reduced correspondingly.
Network topology Maximum cable length
Free topology without repeater 500 m
Free topology with one repeater 1000 m
Free topology maximum device-to-device 500 m
Bus topology single terminated 500 m
Bus topology double terminated without repeater 2700 m
Bus topology double terminated with one repeater 5400 m
Bus topology maximum stub length 3 m
The length statements in the tables above are valid for bus cable with the following properties:
- Impedance: 135 to 165 Ohm at a measuring frequency from 3 to 20 MHz
- Resistance: <110 Ohm/km
- Capacitance: <30 pF/m
- Damping: max. 9 dB over the whole wire length
- Cross section: max. 0.34 mm 2 , corresponding to AWG 22
- Cable type: twisted in pairs, 1 x 2, or 2 x 2, or 1 x 4 wires
- Screening: Copper-braided screen or braided screen and foil screen
Use of the same cable type throughout the entire segment is recommended to avoid impedance mismatch.
AF-600FP BACnet
11
3