Engineering Documentation

Table Of Contents
Chapter 2 Network Electrical Systems
RS-485 ALN (P2/P3) and FLN (P1) Trunk Communications Wiring
125
-3002
45 | 231
Fig. 21: BACnet Nodes on Siemens Controllers or Third-Party Equipment.
RS-485 ALN (P2/P3) and FLN (P1) Trunk
Communications Wiring
BACnet RS-485 FLN
The BACnet FLN supports communication for BACnet devices over 2-wire RS-485
trunks.
Wiring from the field panel FLN port to the BACnet device uses the same wiring
guidelines as the RS-485 FLN (P1) trunk. See the Table 1.5-pair Cable Specifications
[ 37].
See the section RS-485 MS/TP Communications [ 33] for connecting 3-wire RS-485
trunks.