Connecting To The Bacnet Network; Setting The Bacnet Transmission Speed; Selecting The Device Object Instance Number - Grundfos CIM 300 User Manual

2.3 Connecting to the BACnet network

Use a screened, twisted-pair cable.
BACnet terminal Recommended colour
Plus Red
Minus Green
Ground Grey
The ANSI/ASHRAE BACnet standard states that the cable screen
must only be earthed at one end of the segment to prevent earth
fault currents.

2.4 Setting the BACnet transmission speed

Set the transmission speed correctly before CIM 300 is ready to
communicate on the BACnet MS/TP network. Use DIP switches
SW4 and SW5 to set the transmission speed.
The default transmission speed is 9600 bit/s, but we recommend
higher speeds for better data throughput. All devices on the BACnet
MS/TP network must communicate at the same transmission
speed.
SW4 SW5
BACnet transmission speed settings
2.4.1 DIP switch settings
Available transmission speeds in bit/s: 9600, 19200, 38400 and
76800.
Use DIP switches SW4 and SW5 to select the desired speed.
Transmission speed
[bit/s]
9600
19200
38400
76800
The default transmission speed is 9600 bit/s, as per the BACnet
MS/TP standard. The transmission speed will be effective
immediately after setting the values of the DIP switch.
Data signal
Positive
Negative
Ground
SW4 SW5
OFF OFF
OFF ON
ON OFF
ON ON

2.5 Selecting the Device Object Instance Number

The Device Object Identifier value consists of two components:
• a 10-bit Object Type (bits 22 to 31)
• a 22-bit Instance Number (bits 0 to 21).
31 22 21
Object type
10 bits
Bit numbers
The Object Type is fixed and determines that it is a Device Object.
The Instance Number is a numeric code that is used to identify the
device. It must be unique inter-network-wide, i.e. on all
interconnected networks.
CIM 300 offers two different approaches to setting the BACnet
Device Object Instance Number: default and custom, both
described in the following subsections.
2.5.1 Default Instance Number
By default, CIM 300 uses a pre-defined Device Object Instance
Number, which is 227XXX where XXX is the BACnet MAC address.
This gives an Instance Number range of 227000 to 227127.
Example
The BACnet MAC address is set to 20 via the hexadecimal rotary
switches, so the Device Object Instance Number is 227020.
Related information
2.7 Selecting the BACnet MAC address
2.5.2 Custom Instance Number
To use the complete Instance Number range, set the new Instance
Number with the BACnet object Custom Device Object Instance
Number (AV, 0), and set SW3 to ON. This will immediately set the
new Device Object Instance Number.
SW3
Device Object Instance Number
Device Object Instance Number
Default (227000 + BACnet MAC address)
Custom, set with object (AV, 0)
The default Present_Value of the Custom Device Object Instance
Number is 231.
Example
The Present_Value of the Custom Device Object Instance Number
(AV, 0) is 231, so the Device Object Instance Number is 231.
The Present_Value of the Custom Device Object Instance
Number cannot be 4194303, as this is a reserved value.
...
0
Instance Number
22 bits
SW3
OFF
ON
9