ABB AC 800F

4 Cabling the AC 800F
4-79
Terminate the two signal pairs at both bus ends. Three terminating resistors
(1.0 kohms, 100 ohms, 1.0 kohms) are to be used, as seen in Fig. 4-55.
1. Serial fieldbus module installed at the end of the bus cable
Cable fieldbus module FI 820F and the other bus nodes as shown in Fig. 4-55.
Use a shielded 2-wire twisted-pair cable, 1 x 2 x 0.25 mm². The cable shield is put
on the P-terminals of the terminal block TB 870F. Keep the branch cables to the
nodes as short as possible.
Fig. 4-55 Cabling FI 820F via RS485 interface, case 1
Terminate the two signal pairs on the AC 800F side and on the device to be
connected. There are three possible terminations on the AC 800F side:
• Internal termination
• External termination with internal supply
• External termination with external supply
Only use one of the possible terminations. Using two terminations at
one bus end will cause communication problems!