JOHNSON CONTROLS
151
SECTION 10 – MAINTENANCE
FORM 150.27-NM1
ISSUE DATE: 09/30/2015
10
BACnet and Modbus Communications
Chiller data that can be read and modified using spe-
cific BACnet or Modbus Register Addresses; and the
data associated with the addresses, is outlined in the
following description:
Analog Write Points
This data can be read and modified using a BACnet
or Modbus network connection. The Modbus Register
Address for these points is 1025 + AV #.
Binary Write Points
This data can be read and modified using a BACnet
or Modbus network connection. The Modbus Register
Address for these points is 1537 + BV #.
Analog Read Only Points
This data can be read using a BACnet or Modbus net-
work connection and can NOT be modified using this
connection. The Modbus Register Address for these
points is 513 + AI #.
Binary Monitor Only Points
This data can be read using a BACnet or Modbus net-
work connection and can NOT be modified using this
connection. The Modbus Register Address for these
points is 1281 + BI #.
Refer to Table 30 on page 152 for complete list of
BACnet and Modbus registers.
The latest data map information is listed
on the Johnson Controls Equipment In-
tegration website.
Communications Data Map Notes
1.
IPU II based units are configured for Native BAC
-
net MS/TP and Modbus RTU communications.
MicroGateway or E-Link not required for these
two communication protocols.
2. BACnet Object Types:
•
0 = Analog In
•
1 = Analog Out
•
2 = Analog Value
•
3 = Binary In
•
4 = Binary Output
•
5 = Binary Value
•
8 = Device
•
15 = Alarm Notification (0 through 127 are
reserved ASHRAE Objects)
3. WC= Inches of water column
CFM = Cubic Feet per Minute
FPM = Feet per Minute
PSI = Lbs per square inch
Pa = Pascals
kPa = Kilopascals
PPM = Part per Million
kJ/kg = Kilojoules per Kilogram
4.
Water Cooled Scroll units use the same firmware
as Air Cooled Scroll units, ignoring Fan Control.
