Bacnet Ms/Tp, Cim 300 Setup; Bacnet Bus Topology; Cim 300 Bacnet Module - Grundfos CIM 300 BACnet MS/TP Instructions Manual

3. BACnet MS/TP, CIM 300 setup

3.1 BACnet bus topology

The Grundfos CIM/CIU 300 is connected as a BACnet MS/TP
master directly to the BACnet MS/TP network.
M
S
LT
BR
M
Example of BACnet MS/TP network
Pos. Description
M Master
S Slave
LT Line Termination
BR Bias Resistors
The BACnet MS/TP is a multi-master system which means that
there can be more than one master on the network. It uses a token
to control access to the bus network. A master node may initiate the
transmission of a data telegram when it holds the token. Both
master and slave nodes may transmit data telegrams in response to
requests from master nodes, but slaves never hold the token.
Master nodes pass the token between them.
A BACnet MS/TP segment is a single contiguous medium to which
BACnet nodes are attached. Segments can be connected by use of
repeaters or bridges, thus forming networks.
Multiple networks may be interconnected by BACnet routers to form
a BACnet inter-network.
3.1.1 Line termination resistors
Line termination must be connected at each of the two ends of the
segment medium. The CIM/CIU 300 has optional line termination
resistor on board.
3.1.2 Bias resistors
At least one set, and no more than two sets, of network bias
resistors must exist for each segment so that an undriven
communications line is held in a guaranteed logical one state. The
bias provides a reliable way for stations to detect the presence or
absence of signals on the line. An unbiased line takes an
indeterminate state in the absence of any driving node.
The CIM/CIU 300 has no bias resistors.
S
M
LT
S
S

3.2 CIM 300 BACnet module

1 2 3 4
CIM 300 BACnet module
Pos. Designation Description
BACnet Plus terminal, RS-485 positive
1 Plus
data signal
BACnet Minus terminal, RS-485 negative
2 Minus
data signal
3 Ground BACnet ground terminal
On and off switches for termination
4 SW1/SW2
resistor
Switches for selecting the BACnet
5 SW3/SW4/SW5 transmission speed and the default or
custom Device Object Instance Number
Red and green status LED for BACnet
6 LED1
communication
Red and green status LED for internal
7 LED2 communication between CIM 300 and the
booster system
Hexadecimal rotary switch for setting the
8 SW6 BACnet MAC address (four most
significant bits)
Hexadecimal rotary switch for setting the
9 SW7 BACnet MAC address (four least
significant bits)
8
9
5 6 7
9