Daikin McQuay MicroTech III User manual

Engineering Data ED 15121
Group: Controls
Part Number: ED 15121
Date: October 2009
Supersedes: New
© 2009 McQuay International
MicroTech®III
Chiller Unit Controller
Protocol Information
Modbus®Protocol
•Pathfinder™ Chiller, Model AWS

2 ED 15121
Table of Contents
TABLE OF CONTENTS........................................................................................................................................................ 2
LIMITED WARRANTY............................................................................................................................................................. 4
NOTICE .................................................................................................................................................................................. 4
REVISION HISTORY................................................................................................................................................................ 4
SOFTWARE REVISION............................................................................................................................................................. 4
REFERENCE DOCUMENTS....................................................................................................................................................... 4
INTRODUCTION.................................................................................................................................................................... 5
CHILLER MODELS.................................................................................................................................................................. 5
CONTROLLER DATA POINTS .................................................................................................................................................. 5
MODBUS PROTOCOL INFORMATION............................................................................................................................ 6
COMPATIBILITY ..................................................................................................................................................................... 6
PROTOCOL DEFINITIONS ........................................................................................................................................................ 6
VALID FUNCTION CODES....................................................................................................................................................... 6
VALID ERROR CODES ............................................................................................................................................................ 7
MODBUS ADDRESSING........................................................................................................................................................... 7
MODBUS DATA POINT ........................................................................................................................................................... 7
EXAMPLE DATA POINT:CHILLER ON/OFF............................................................................................................................. 8
CONFIGURING THE UNIT CONTROLLER.................................................................................................................................. 8
TYPICAL APPLICATION: MINIMUM INTEGRATION..................................................................................................... 9
DISPLAY IMPORTANT DATA POINTS ...................................................................................................................................... 9
PROTOCOL POINT SUMMARY....................................................................................................................................... 10
REGISTER MAPPING............................................................................................................................................................. 10
ALARM DATA POINTS.......................................................................................................................................................... 16
DETAILED DATA POINT INFORMATION...................................................................................................................... 19
ACTIVE CAPACITY LIMIT OUTPUT ....................................................................................................................................... 19
ACTIVE SETPOINT................................................................................................................................................................ 19
ACTUAL CAPACITY.............................................................................................................................................................. 19
ALARM DIGITAL OUTPUT .................................................................................................................................................... 19
APPLICATION SOFTWARE VERSION...................................................................................................................................... 20
CAPACITY LIMIT SETPOINT -NETWORK .............................................................................................................................. 20
CHILLER CAPACITY LIMITED............................................................................................................................................... 20
CHILLER CURRENT .............................................................................................................................................................. 20
CHILLER ENABLE OUTPUT................................................................................................................................................... 21
CHILLER ENABLE SETPOINT ................................................................................................................................................ 21
CHILLER LOCAL/REMOTE.................................................................................................................................................... 21
CHILLER LOCATION............................................................................................................................................................. 21
CHILLER MODE OUTPUT...................................................................................................................................................... 21
CHILLER MODE SETPOINT -NETWORK................................................................................................................................ 22
CHILLER MODEL.................................................................................................................................................................. 22
CHILLER ON/OFF................................................................................................................................................................. 22
CHILLER STATUS ................................................................................................................................................................. 22
CLEAR ALARMS -NETWORK................................................................................................................................................ 22
COMPRESSOR DISCHARGE REFRIGERANT TEMPERATURE.................................................................................................... 23
COMPRESSOR RUN HOURS................................................................................................................................................... 23
COMPRESSOR STARTS.......................................................................................................................................................... 23
COMPRESSOR SUCTION REFRIGERANT TEMPERATURE ........................................................................................................ 23
CONDENSER REFRIGERANT PRESSURE................................................................................................................................. 24
CONDENSER SATURATED REFRIGERANT TEMPERATURE ..................................................................................................... 24
COOL SETPOINT -NETWORK................................................................................................................................................ 24
CURRENT DATE &TIME ...................................................................................................................................................... 24

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EVAPORATOR ENTERING FLUID TEMPERATURE...................................................................................................................25
EVAPORATOR FLOW SWITCH STATUS ..................................................................................................................................25
EVAPORATOR LEAVING FLUID TEMPERATURE.....................................................................................................................25
EVAPORATOR PUMP RUN HOURS.........................................................................................................................................25
EVAPORATOR PUMP STATUS................................................................................................................................................25
EVAPORATOR REFRIGERANT PRESSURE...............................................................................................................................25
EVAPORATOR SATURATED REFRIGERANT TEMPERATURE ...................................................................................................26
FAULT ALARM CODE ...........................................................................................................................................................26
FAULT ALARM INDEX ..........................................................................................................................................................26
ICE SETPOINT -NETWORK....................................................................................................................................................26
OUTDOOR AIR TEMPERATURE..............................................................................................................................................26
PROBLEM ALARM CODE.......................................................................................................................................................26
PROBLEM ALARM INDEX......................................................................................................................................................27
RUN ENABLED .....................................................................................................................................................................27
UNITS...................................................................................................................................................................................27
WARNING ALARM CODE......................................................................................................................................................27
WARNING ALARM INDEX.....................................................................................................................................................27
ALARMS................................................................................................................................................................................28
ALARM CLASSES..................................................................................................................................................................28
FAULT ALARMS....................................................................................................................................................................28
PROBLEM ALARMS...............................................................................................................................................................28
WARNING ALARMS ..............................................................................................................................................................28
ALARM HANDLING...............................................................................................................................................................28
ALARM DIGITAL OUTPUT.....................................................................................................................................................28
CLEAR ALARMS -NETWORK................................................................................................................................................29
ACTIVE ALARMS..................................................................................................................................................................29
APPENDIX A: ASCII CHARACTERS CONVERSION TABLE.....................................................................................33
INDEX.....................................................................................................................................................................................34
TABLE OF TABLES
Table 1. Valid Function Codes..................................................................................................................................................6
Table 2. Valid Error Codes.......................................................................................................................................................7
Table 3. Significant Data Points................................................................................................................................................9
Table 4. Chiller Data Points....................................................................................................................................................10
Table 5. Circuit Data Points ...................................................................................................................................................14
Table 6. Compressor Data Points ...........................................................................................................................................15
Table 7. Pump Data Points .....................................................................................................................................................15
Table 8. Miscellaneous Data Points........................................................................................................................................15
Table 9. Warning Alarms ........................................................................................................................................................16
Table 10. Problem Alarms.......................................................................................................................................................16
Table 11. Fault Alarms............................................................................................................................................................17
Table 12. Modbus Warning Alarms.........................................................................................................................................29
Table 13. Modbus Problem Alarms.........................................................................................................................................30
Table 14. Modbus Fault Alarms..............................................................................................................................................31

4 ED 15121
Limited Warranty
Consult your local McQuay Representative for warranty details. Refer to Form 933-43285Y. To find your local McQuay
Representative, go to www.mcquay.com.
Notice
© 2009 McQuay International, Minneapolis MN. All rights reserved throughout the world.
McQuay International reserves the right to change any information contained herein without prior notice. The user is
responsible for determining whether this product is appropriate for his or her application.
™ ® The following are trademarks or registered trademarks of their respective companies. Modbus is a registered
trademark of Gould, Inc. Windows is a registered trademark of Microsoft Corporation. MicroTech III is a registered
trademark of McQuay International.
Revision History
ED 15121 October 2009 Preliminary release.
Software Revision
This edition documents all versions of the standard MicroTech®III Chiller Unit Controller firmware and all subsequent
revisions until otherwise indicated.
Reference Documents
Company Number Title Source
McQuay
International IM 969 MicroTech III Modbus Communication Module Installation Manual www.mcquay.com
McQuay
International IM 1002 (50Hz )
IM 997 (60Hz) Pathfinder™Air Cooled Chiller Installation Manual www.mcquay.com
McQuay
International OM 998 Pathfinder Air Cooled Chiller Operation Manual www.mcquay.com
Modbus-IDA.ORG MODBUS Application Protocol Specification V1.1b www.Modbus.org
Modbus-IDA.ORG MODBUS over Serial Line Specification and Implementation Guide
V1.02 www.Modbus.org

5 ED 15121
Introduction
This document contains the necessary information to incorporate a MicroTech®III Chiller Unit Controller from McQuay
International into your Building Automation System (BAS). It includes all necessary Modbus®variables and
corresponding MicroTech III Chiller Unit Controller data points. Modbus terms and principles are not defined. Refer to
the appropriate specifications for definitions and details.
Chiller Models
The following table lists the model designators of McQuay International Chiller units and the corresponding description.
AWS Air-Cooled World Screw
Controller Data Points
The MicroTech III Chiller Unit Controller contains data points or unit variables that are accessible from two different
user interfaces: the unit keypad/display or a Modbus serial network. Not all points are accessible from each interface.
This manual lists all important data points and the corresponding network path for each applicable interface. Refer to the
applicable Operation Manual for keypad/display details.
NOTICE
The MicroTech III Chiller Unit Controller maps additional Modbus registers that are not
included in this document. These registers are for internal use only. Please contact McQuay
Controls Customer Support at 866-462-7829 for assistance with Modbus integration.

6 ED15121
Modbus Protocol Information
Compatibility
The MicroTech III Chiller Unit Controller can be configured in an interoperable Modbus network. The controller must
have the corresponding Modbus Communication Module installed.
The MicroTech III Chiller Unit Controller conforms to the published Modbus standards. Refer to www.Modbus.org for
more information.
Protocol Definitions
The Modbus protocol is a standardized Application Level (OSI Level 7) protocol used in interoperable Industrial Control
networks. Modbus provides the communication infrastructure necessary to integrate products manufactured by different
vendors and to integrate control services that are now independent.
It specifies how requests from the client are sent to a server and how servers reply. The client constructs a PDU (protocol
data unit) and sends it to a specific server or broadcasts it to all servers. The PDU contains a function code that defines
the action the client is requesting from the server(s). The PDU also includes a data field that further defines the action to
the server, for example, the location of the data to be read.
A normal reply from a server includes the same function code and a response data field. In the case of a read operation,
the response data field contains the requested data. In the case of a write operation, the response data field contains an
echo of the write data of the request command. If the server detects an error in the transmission, the reply to the client
includes and exception function code and the response data field contains an exception code.
Controllers can communicate on standard Modbus networks using one of two transmission modes: ASCII or RTU. Users
select the serial port communication parameters (baud rate, parity mode, etc), during configuration of the controller. The
mode and serial parameters must be the same for all devices on a Modbus network. Transmission mode determines how
information is packed into the message fields and decoded. In RTU mode, each byte contains two hexadecimal
characters, and in ASCII mode, each byte contains one ASCII character. The MicroTech III Chiller Unit Controller
uses the RTU mode only.
Valid Function Codes
The MicroTech III Chiller Unit Controller supports eight public function codes (see Table 1.) However, the MicroTech
III Chiller Unit Controller contains only Holding Registers (4xxxx).
Table 1. Valid Function Codes
Function Code Description Definition
01 (0x01) Read Coil Status Reads the On/Off status of discrete outputs.
02 (0x02) Read Input Status Reads the On/Off status of discrete inputs.
03 (0x03) Read Holding Registers Used to read 1 to approximately 125 contiguous input registers in a remote
device.
04 (0x04) Read Input Registers Reads the contents of input registers.
05 (0x05) Force Single Coil Force a single coil to on or off.
06 (0x06) Write Single Register Used to write a single holding register to a remote device.
15 (0x0F) Write Multiple Coils Forces each coil in a sequence of coils to either On or Off.
16 (0x10) Write Multiple Registers Used to write a block of 1 to approximately 120 contiguous registers in a remote
device.

7 ED 15121
Valid Error Codes
The MicroTech III Chiller Unit Controller supports all exception codes. See Table 2 below for a description of valid
error codes.
Table 2. Valid Error Codes
Error Codes Description Definition
01 Illegal Function The function code received in the query is not an allowable action for the server (or slave).
02 Illegal Data Address The data address received in the query is not an allowable address for the server (or slave).
03 Illegal Data Value A value contained in the query data field is not an allowable value for server (or slave).
04 Slave Device Failure An unrecoverable error occurred while the server (or slave) was attempting to perform the
requested action.
05 Acknowledged The server (or slave) is has accepted, and is processing, the request.
06 Slave Device Busy The server (or slave) is busy processing a command. The client (or master) should retransmit
when the server (or slave) is free.
08 Memory Parity Error
The server (or slave) attempted to read record file, but detected a parity error in the memory.
The client (or master) can retry the request, but service may be required on the server (or
slave) device.
0A Gateway Path
Unavailable The gateway may be configured incorrectly or overloaded.
0B Gateway Target Device
Failed to Respond No response from the target device.
Modbus Addressing
Each function code implies access to a specific Modbus reference set. Therefore, the leading digit is not included in the
address field of a Modbus message. The Modbus Communication Module supports zero-based addressing. For
example, holding register 40003 is addressed as 0002 in a Modbus message.
Modbus Data Point
Each data point accessible from a Modbus network is described with a table that gives the data type and holding register.
If the data point represents an enumerated variable, the enumerations are also listed.
When a variable is spans multiple Holding Registers, it is important to know how the data is represented in those
Holding Registers. This is best shown with an example. Let’s use Compressor Run Hours. Circuit 1, compressor 1 run
hours is located at holding registers 74-75 (40074-40075). If the operating hours is 99900 (0x0001 0x863C), the
registers will be as follows:
•74= 0x863C
•75 = 0x0001
For strings, the interpretation differs. In this case, each holding register can contain two characters. If a string spans
multiple registers, the first register (lowest register number) contains the 2 left-most characters of the string. Since the
MicroTech III Chiller Unit Controller only supports Modbus RTU, use Appendix A: ASCII Character to translate the
numerical data to their corresponding ASCII characters. An example of registers that contain string data is Application
Version which is located at holding registers 334-338 (40334-40338). The following example shows the holding register
and its value (in hexadecimal), followed by the ASCII character translation.
•334= 0x3235
•0x32 = “2”
•0x35 = “5”
•335= 0x3035
•0x30 = “0”
•0x35 = “5”
•335= 0x3036
•0x30 = “0” Application Version = 2505067100
•0x35 = “6”
•337= 0x3731
•0x37 = “7”
•0x31 = “1”
•338= 0x3030
•0x30 = “0”
•0x30 = “0”

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Example Data Point: Chiller On/Off
This output data point indicates the current state of the chiller. The OFF state is represented by state = FALSE and value
= 0. The other discrete states are represented by state = TRUE and value > 0.
Data Type Holding Register Measurement Units Valid Range
RO Holding Register 8 Chiller State N/A 0=Off
1=On
Data Type
Data is represented as either single-bit elements or 16-bit elements. A single-bit element is referred to as a Discrete Input
when it refers to read-only data and as a Coil when it refers to read-write data. A 16-bit element is referred to as a Input
Register when it refers to read-only data and as an Holding Register when it refers to read-write data.
All of the Modbus registers defined in the MicroTech III Chiller Unit Controller are 16-bit Holding Registers. Some are
read only (RO) and some are read-write (RW).
Holding Register
There are up to 65,536 elements of each data type in a Modbus device. Data elements are numbered from 1 to 65,536 in
each type. Data elements are addressed with an index in the range from 0 to 65,535. The index is not the address of the
data element in the unit controller memory. The index is used in Modbus PDUs to specify the location the data in the
unit controller. This means, for example, that data element number 1 (ie, holding register 40001) is addressed using
index 0 in the PDU.
In addition, the function code field portion of the message already specifies a ‘holding register’ operation. Therefore the
‘4xxxx’ reference is implicit. This document follows this assumption and has published the holding registers without
the implicit 4xxxx. For example, Holding Register 8 is actually Holding Register 40008.
Valid Range
Some properties are standard data types and some are enumerated sets. If the property value represents a range of values,
e.g., temperature or pressure, a range of values is given. If the property value is an enumerated set, all enumerated values
and corresponding meaning are given.
Configuring the Unit Controller
The MicroTech III Chiller Unit Controller and the Modbus Communication Module ship with default parameter values.
Default values may be changed with the unit keypad or via the network. Parameters must be adjusted to accommodate
your particular network. See the appropriate Operation Manual for default values and keypad operating instructions. See
the MicroTech III Modbus Communication Module Installation Manual, IM 969, for details regarding network
parameters available via the unit controller keypad/display. All documents are available on www.mcquay.com.

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Typical Application: Minimum Integration
Display Important Data Points
Typical workstation displays of MicroTech III Chiller Unit Controller attributes include the following significant data
points (page number of detailed description in parenthesis). Each data point is tagged with a number that identifies it in
the Protocol Point Summary Tables. These particular data points are indicated with boldface type. Refer to Tables 4-8.
Table 3. Significant Data Points
No. Configuration No. Temperatures No. Setpoints No. Alarms
1 Chiller Status (22) 5 Evaporator Entering
Fluid Temperature (25) 9 Cool Setpoint –
Network (24) 11 Warning Alarm
Code(27)
2 Chiller Mode Setpoint
– Network (22) 6 Evaporator Leaving
Fluid Temperature (25) 10 Capacity Limit Setpoint
– Network (20) 12 Problem Alarm
Code(26)
3 Actual Capacity (19) 13 Fault Alarm Code(26)
4 Chiller Enable
Setpoint (21) 14
Clear Alarms -
Network(29)
You can display any number of additional data points based on job requirements or individual preference. See Modbus
Data Points on page 7 for lists of all Modbus properties available to the network. For a more detailed description of all
available data points, see the Detailed Data Point Information section on page 19 of this document.

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Protocol Point Summary
The following section provides a summary of Modbus properties available from the MicroTech III Chiller Unit
Controller. Tables 4-8 contains the complete list of chiller, circuit, compressor, pump, and miscellaneous data points
respectively. The items shown in boldface represent the minimum integration properties (as identified previously in
Table 3.)
Register Mapping
The Modbus Communication Module supports zero-based addressing. For example, holding register 40002 is addressed
as 0001 in a Modbus message. The following tables assume 4xxxx addressing. For example, 1 will be holding register
40001.
Table 4. Chiller Data Points
Network Control Property Page Holding
Register
(4xxxx)
Read/
Write Description
Chiller Local/Remote 21 1 R 0=Remote, 1=Local
Chiller Enable Output 21 2 R 0=Disable, 1=Enable
Run Enabled 27 3 R 0=Off 1= RunAllowed
Chiller Capacity Limited 20 4 R 0=Not Limited, 1=Limited
Alarm Digital Output 19 5 R 0=No Alarm, 1=Alarm
Evaporator Flow Switch Status 25 6 R 0=No Flow, 1=Flow
Chiller On/Off 22 8 R 0=Off, 1=On
*Chiller Enable Setpoint (4) 21 9 R/W 0=Disable, 1=Enable, 2=Null
*Clear Alarms – Network (14) 22 10 R/W 0=Normal, 1=Clear Alarms, 2=Null
Chiller Mode Output 21 11 R 1=Ice, 2=Cool, 3=Heat, 4=Cool/Heat Recovery, 5=Defrost
Active Setpoint 19 12 R 15.08°F to 149.9°F (-9.4°C to 65.5°C)
*Actual Capacity (3) 19 13 R 0 - 100%
Active Capacity Limit Output 19 14 R 0 - 100%
*Chiller Status (Chiller Run Mode) (1) 22 15 R 1=Off, 2=Start, 3=Run, 4=Pre Shutdown, 5=Service
*Evaporator Entering Fluid Temperature (5) 25 16 R -40-230°F (-40-110°C)
*Evaporator Leaving Fluid Temperature (6) 25 17 R -40-230°F (-40-110°C)
Outdoor Air Temperature 26 24 R -40-230°F (-40-110°C)
Chiller Current 20 25 R 0-10,000 Amps
Warning Alarm Index 27 28 R 0=No Alarms
5=Evaporator pump maintenance
7=Compressor maintenance Circuit #n
8=Bad setpoint override input
9=Bad demand limit input
11=Unit power restore
12=Circuit failed pumpdown
13=External Event
Problem Alarm Index 27 29 R 0=No Alarms
64=RESTART DELAYED-Power Loss While Running Circuit #n
65=START INHIBITED - Ambient Temperature Low
67=INHIBIT LOAD – Condenser Pressure High Circuit #n
69=UNLOAD – Condenser Pressure High Circuit #n
76=INHIBIT LOAD - Evaporator Pressure Low Circuit #n
78=UNLOAD - Evaporator Pressure Low Circuit #n
Fault Alarm Index 26 30 R 0=No Alarms
127=COMP SHUTDOWN–Low pressure ratio #n
128=COMP SHUTDOWN-Outside Air Temp Sensor Fault
135=COMP SHUTDOWN–Motor Temp High Circuit #n
136=COMP SHUTDOWN–Motor Temp Sensor Fault #n
142=COMP SHUTDOWN-Condenser Pressure Sensor Fault #n
145=COMP SHUTDOWN-Condenser Pressure High #n,
147=COMP SHUTDOWN-Discharge Temp Sensor Fault #n
148=COMP SHUTDOWN-Discharge Temp High #n
150=UNIT SHUTDOWN-Evaporator Water Flow Loss
151=UNIT SHUTDOWN–Evaporator Leaving Water Temp Low
(Freeze)
153=COMP SHUTDOWN-Evaporator Pressure Low #n,