219
JOHNSON CONTROLS
SECTION 10 – MAINTENANCE
FORM 150.67-NM1
ISSUE DATE: 4/28/2017
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 41 for complete list of BACnet and
Modbus registers.
The latest data map information is
listed on the Johnson Controls Equip-
ment Integration website.
Communications Data Map Notes:
(See Table 41)
1. IPUIIbasedunitsareconguredforNativeBAC-
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 Notifica-
tion (0 through 127
are reserved ASHRAE
Objects).
3. Abbreviations:
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 Mil-
lion
kJ/kg = Kilojoules per
Kilogram.
4. WaterCooledScrollunitsusethesamermware
as Air Cooled Scroll units, ignoring Fan Control.
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