Danfoss FCM 300 Operating Instructions Manual page 19

The bus termination
68 = RxD/TxD-P∼ (red cable)
It is essential that the bus line be terminated properly.
A mismatch of impedance may result in reflections
on the line that will corrupt data transmission.
- The PROFIBUS is provided with a suitable
termination which may be activated by the switches
of the RS485 switch block located just above the
18
FCM 300 / FCD 300 / VLT
®
2800 / DP V1 PROFIBUS
69 = RxD/TxD-N∼ (green cable)
terminal block 67-70 (see drawing below). The
switches 1 and 2 should be on to terminate the bus.
- Most masters and repeaters are equipped
with their own termination.
- If an external termination circuit consisting of three
resistors is connected to the bus line a 5 V d.c.
power supply must be used, please note that this
must be galvanically isolated from the a.c. line.
MG.90.A5.02 - VLT is a registered Danfoss trademark