ABB ACH550 Installation Manual page 19

8. If more than one MS/TP device is connected to the network,
connect the MS/TP wires from the segment cable to B (+), A (-),
AGND terminals and to Shield. The connectors of the pre-
configured cables are designed to take up to 2.5 mm
sectional area per connector.
See also Connection examples
Note: A BACnet MS/TP network needs to have at least one pair of
network bias resistors switched on. For this reason the router
module is equipped with network bias resistors. The first and
second DIP switches of the router module are network bias
resistors (560 ohms both).
The DIP switch is on the right in the figure above.
9. If you use the internal DIP switch of the drive, set the DIP
switches of the router module to zero (that is, do not use the
network bias resistors of the router module).
Note: Both the first and the last device of the segment needs to
have termination resistors.
10. The third DIP switch of the router module is a 120 ohm
termination resistor. If the router module is physically not the
last device of the segment, set this DIP switch to zero.
on page 37.
Installation of the module
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