19
ED 15121
Detailed Data Point Information
The following section details the information (the data) available to the Building Automation System (BAS) via the
Modbus RTU protocol. This information is used for chiller monitoring and operation. The system integrator also uses
this information to create BAS workstation graphics.
Active Capacity Limit Output
Keypad Menu Path
No Keypad Equivalent
This read only holding register is a measure of the ratio of operating capacity limit to full capacity expressed in percent.
This value is the lowest of all limits specified by the operator, analog Demand Limit input, or Network Capacity Limit
Setpoint.
Data Type
Holding Register
Measurement
Units
Valid Range
RO Holding Register
14
Percent of maximum
capacity
% x 10
0-100%
Active Setpoint
Keypad Menu Path
Main Menu_Active Setpt=
This read only holding register indicates the current setpoint used to control the chiller. Based on the operating mode of
the chiller, this value is derived from the Cooling Setpoint, Ice Setpoint or Heating Setpoint (not available in MicroTech
III Chiller Unit Controller). See “Chiller Mode Output” and “Chiller Mode Setpoint – Network”. The default mode is
Cool. There are three possible setpoints. See “Cool Setpoint – Network”, “Heat Setpoint – Network” and “Ice Setpoint –
Network”.
Data Type
Holding Register
Measurement
Units
Valid Range
RO Holding Register
12
Temperature
°F x 10
°C x 10
15.08°F to 149.9°F
-9.4°C to 65.5°C
Actual Capacity
Keypad Menu Path
Main Menu_Unit Capacity=
This read only holding register indicates the percent of maximum capacity the chiller is producing under the present
operating conditions. At 100%, the chiller may be producing more or less than its nominal rating due to variations in
operating conditions.
Data Type
Holding Register
Measurement
Units
Valid Range
RO Holding Register
13
Percent of chiller capacity
% x 10
0-100%
Alarm Digital Output
Keypad Menu Path
No Keypad Equivalent
This read only holding register indicates whether an alarm condition has occurred. This variable must be polled for alarm
notification.
Data Type
Holding Register
Measurement
Units
Valid Range
RO Holding Register
5
NA N/A
0=No Alarm
1=Alarm
