McQuay MicroTech MAG Instruction Manual

Installation & Maintenance Data IM 620-1
Group: Controls
Part Number: 585524Y
Date: February 1998
© 1998 McQuay International
MicroTech®
Absorption Gateway for Absorption Chillers
MicroTech
Absorption
Gateway
MicroTech
a0170

2IM620-1
Contents
Contents ..................................................................................................................................................................2
Illustrations.............................................................................................................................................................2
Tables:......................................................................................................................................................................3
Introduction............................................................................................................................................................4
General Description......................................................................................................6
Component Data.....................................................................................................................................................6
Microprocessor Control Board........................................................................................................................7
Output Board....................................................................................................................................................10
Input Conditioning Module Terminal Board ...............................................................................................10
Software ID............................................................................................................................................................11
Accessories...........................................................................................................................................................11
Solid State Relay Kit........................................................................................................................................11
Analog Output Expansion Module...............................................................................................................12
MicroTech Monitoring and Networking Options...........................................................................................12
PC Monitoring..................................................................................................................................................12
Network Master Panel.....................................................................................................................................13
Open Protocol...................................................................................................................................................13
Installation..................................................................................................................14
Panel Location and Mounting............................................................................................................................14
Field Wiring...........................................................................................................................................................15
Power.................................................................................................................................................................15
Network Communications...............................................................................................................................15
PC Connection..................................................................................................................................................18
Analog Output Connection............................................................................................................................20
Digital Output Connection.............................................................................................................................21
Network Commissioning.....................................................................................................................................22
Addressing the Controllers............................................................................................................................22
Connecting the Communications Trunk.......................................................................................................23
Service Information ....................................................................................................28
Wiring Diagrams...................................................................................................................................................28
Test Procedures....................................................................................................................................................30
Status LED Diagnostics..................................................................................................................................30
Troubleshooting Power Problems .................................................................................................................31
Troubleshooting Analog Outputs ................................................................................................................32
Troubleshooting Output Boards...................................................................................................................33
Troubleshooting Solid-State Relays.............................................................................................................36
MCB Replacement................................................................................................................................................37
Parts List................................................................................................................................................................37
Illustrations
Figure 1. MAG Panel Layout................................................................................................................................7
Figure 2. Microprocessor Control Board (MCB)...............................................................................................8
Figure 3. Hex Switches Showing 01 Setting.......................................................................................................9
Figure 4. Software ID Label.................................................................................................................................11
Figure 5. Analog Output Expansion Module (AOX-4)...................................................................................12
Figure 6. MAG Panel Dimensions......................................................................................................................14
Figure 7. Typical Field Wiring Schematic: Network Connect MAG.............................................................17
Figure 8. Typical Field Wiring Schematic: Direct Connect MAG.................................................................18
Figure 9. RS-232 Cable Pinouts for 9-Pin Serial Ports (AMP Connector)....................................................19
Figure 10. RS-232 Cable Pinouts for 25-Pin Serial Ports (AMP Connector)................................................20
Figure 11. Analog Outputs Field Wiring Connections...................................................................................21

IM620-1 3
Figure 12. AMP Connector Terminal Configuration.......................................................................................24
Figure 13. AMP Connector - CIC Connection.................................................................................................26
Figure 14. Network Connect MAG Schematic Legend...................................................................................28
Figure 15. Network Connect MAG Schematic.................................................................................................29
Figure 16. Direct Connect MAG Schematic Legend.......................................................................................29
Figure 17. Direct Connect MAG Schematic .....................................................................................................30
Figure 18. MCB Power Supply Terminals.........................................................................................................32
Figure 19. Output Board Relay Socket..............................................................................................................34
Figure 20. Testing a Typical Relay Circuit .......................................................................................................36
Figure 21. Testing a Relay Circuit with a Disconnection...............................................................................37
Tables
Table 1. Read-Only Data.......................................................................................................................................4
Table 2. MAG Accessories ..................................................................................................................................6
Table 3. Green and Red Status LED Indication.................................................................................................9
Table 4. Amber Status LED Indication...............................................................................................................9
Table 5. Program Codes ......................................................................................................................................11
Table 6. Accessory Installation Manuals ........................................................................................................11
Table 7. PC Specification....................................................................................................................................13
Table 8. MAG Panel Environmental Specifications........................................................................................14
Table 9. Port B Voltages: AMP Type Connector............................................................................................24
Table 10. Network Communications Field Wiring Terminals ........................................................................24
Table 11. Network MAG Controller - CIC Connection..................................................................................25
Table 12. Direct MAG Controller - CIC Connection.......................................................................................26
McQuay and MicroTech are registered trademarks of McQuay International.
Monitor and Open Protocol are trademarks of McQuay International.
Microsoft and MS-DOS are registered trademarks of Microsoft Corporation.
IBM is a registered trademark of International Business Machines Corporation.
©1998 McQuay International. All rights reserved throughout the world.

4IM620-1
Introduction
This manual provides information about the MicroTech® MicroTech Absorption Gateway (MAG). It
describes the components, field wiring, and service procedures.
The MAG is an interface between the absorption chiller(s) and a MicroTech or Open Protocol™
building automation system (BAS). The MAG allows the BAS to read data from the absorption chiller,
but does not allow control of the chiller.
See Table 1 for the items that can be read from the absorption chiller through the MAG.
Table 1. Read-Only Data
Analog Data Digital Output Data Digital Input Data
Chilled water inlet/outlet
temperature Absorbent solution pumps Start/stop of pumps and blowers
Hot water inlet/outlet temperatures Refrigerant pump Combustion signal
Low/high temperature generator
temperature Ignition signal Remote Start/stop signals
Cooling water inlet/outlet
temperature Heating, cooling, simultaneous and abnormality indicators
Condensation temperature SVRP and SVRU valves
Remote reset setting Cooling main/heating main
Exhaust gas temperature/steam
condensate temperature Alarms
Fuel control valves 1 and 2 position
Inverter Output Signal
Steam control valve output signal
!
WARNING
Electric shock hazard. Can cause personal injury or equipment damage.
This equipment must be properly grounded. Connections and service to the MicroTech
control panel must be performed only by personnel that are knowledgeable in the operation
of the equipment being controlled.
!
CAUTION
Static sensitive components. A static discharge while handling electronic circuit boards
can cause damage to the components.
Discharge any static electrical charge by touching the bare metal inside the control panel
before performing any service work. Never unplug any cables, circuit board terminal blocks,
or power plugs while power is applied to the panel.

IM620-1 5
NOTICE
This equipment generates, uses and can radiate radio frequency energy and, if not
installed and used in accordance with this instruction manual, may cause interference to
radio communications. It has been tested and found to comply with the limits for a Class A
digital device, pursuant to part 15 of the FCC rules. These limits are designed to provide
reasonable protection against harmful interference when the equipment is operated in a
commercial environment. Operation of this equipment in a residential area is likely to
cause harmful interference in which case the users will be required to correct the
interference at their own expense. McQuay International disclaims any liability resulting
from any interference or for the correction thereof.

6IM620-1
General Description
The MicroTech® Absorption Gateway (MAG) is a microprocessor-based controller used as a read-
only interface between a MicroTech absorption chiller and a MicroTech or Open Protocol partner’s
building automation system (BAS). No control of the absorption chiller is performed through the
MAG.
A MAG is needed for each absorption chiller in a network. If there is only one absorption chiller, a
single MAG can connect to the Open Protocol partner’s integrator, or stand alone as its own network.
This type of configuration is called the Direct Connect MAG. If there are two or more absorption
chillers, a level-1 controller such as a Network Master Panel (MicroTech) or an Open Protocol Master
Panel (Open Protocol) is needed to read and store information from the chillers. This type of
configuration is called the Network Connect MAG.
The base panel is equipped with eight AC power rated relays plus the necessary hardware to support
the addition of accessories listed in Table 2. For more information on the MAG accessories, see the
“Accessories” section in this manual.
Table 2. MAG Accessories
Accessories Function
Analog Output Expansion Module (AOX-4) Adds analog outputs
Solid-State Relay Kit (SSR) Adds digital outputs
Component Data
Figure 1 shows the control panel layout for the MAG. The main components of the controller are the
Microprocessor Control Board (MCB), the Output Board (OB) and the Input Conditioning Module
(ICM) Terminal Board. All of these major components are mounted inside a standard NEMA 1
enclosure. They are interconnected by ribbon cables, shielded multi-conductor cables, or discrete
wiring. Power for the system is provided through transformers T1 and T2.
Following are descriptions of these MicroTech components and their input and output devices.

IM620-1 7
Figure 1. MAG Panel Layout
T1
T2
MCB
GND
L2
Snap Track
ICM Terminal Board
OB
5V
D.C. 13V D.C. 13V GRD 13V GRD 24V GRD 24V A.C.
13V
D.C.
L1
Microprocessor Control Board
The Microprocessor Control Board (MCB) is shown in Figure 2. It contains a microprocessor that is
preprogrammed with the software required to monitor the data from the absorption chiller(s) and other
equipment that is connected to the MAG such as sensors or actuators. The various MCB
connections and components are described below.

8IM620-1
Figure 2. Microprocessor Control Board (MCB)
RUNNING
RESET
ACTIVE OUTPUT 0
CPU
STATUS
POWER FUSES
[BUSSMAN GDC-T2A]
POWER IN
[18-24 VCT]
AC AC GND GND
AUX/OUT
DIGITAL OUTPUTS
ANALOG INPUTS DIGITAL INPUTS
HI
ADDRESS
LO
KEYPAD /LCD DISPLAY
COMMUNICATIONS
PORT A PORT B
[FUSE: BUSSMAN MCR-1/4]
FUSE 1
23 4
Hex switches
Microprocessor status LED's
EXPANSION BUS
Digital Outputs Connection
After processing all input conditions and network data, the MCB sends the appropriate output
signals to output devices through the Digital Outputs port via a plug-in ribbon cable.
Aux/Out Terminal Strip
The Aux/Out terminal strip provides 5 Vdc and 13 Vdc to the MAG field wiring terminal strip. The 5
Vdc is used to power auxiliary equipment. The 13 Vdc can be used to power an Analog Output
Expansion Module (see the “Accessories” section of this manual for more information on the Analog
Output Expansion Module).
Power In Connector
The MCB receives 18 Vac, center-tapped power through transformer T2 and the Power In connector.
This power drives all logic and communications circuitry, and the Aux/Out terminal strip. Refer to the
panel’s wiring diagram or Figure 15 for more information.
Power Fuses
Two identical 2-amp fuses are located to the right of the Power In terminal strip. These fuses are in the
MCB power supply circuit.
Microprocessor Status LEDs
The green, red, and amber LEDs on the MCB provide information about the operating status of the
microprocessor. The amber LED also indicates the existence of alarm conditions.
Following is the normal start-up sequence that the three status LEDs should follow when power is
applied to the MCB:
1. The red (“Reset”) LED turns on and remains on for approximately 5 seconds. During this period
the MCB performs a self-test.
2. The red LED turns off and the green (“Running”) LED turns on. This indicates that the
microprocessor has passed the self-test and is functioning properly.

IM620-1 9
3. The amber (“Active”) LED remains on for 1 second and off for 1 second when communications
exists between the MAG and the absorption chiller. If the LED is on for 2/10 of a second and off for
2/10 of a second, this indicates that communications between the MAG and the absorption chiller
does not exist.
If the above sequence does not occur after power is applied to the controller, there is a problem with
the MCB or its power supply. For more information, refer to the “Test Procedures” section of this
manual, which is under “Service Information.”
Tables 3 and 4 summarize the green, red, and amber status LED indications.
Table 3. Green and Red Status LED Indication
Green LED State Red LED State Indication
Off Off No power to MCB
Off On* Self-test failure or power supply
problem
On Off MCB operating normally
* For longer than 5 seconds.
Table 4. Amber Status LED Indication
Amber LED State Indication
On 1 second
Off 1 second Communications exists between the MAG and the absorption chiller
On 2/10 second; Off 2/10 second Communications does not exist between the MAG and the absorption
chiller
Hex Switches
The MCB includes two hex (hexadecimal) switches that are used to set the MAG controller’s network
address.
The HI and LO hex switches are shown in Figure 3. A “hex switch setting” is defined as the HI switch
digit followed by the LO switch digit. For example, a hex switch setting of 2F would have the HI switch
set to “2” and the LO switch set to “F.” Refer to “Addressing the Controllers” in the “Network
Commissioning” section of this manual for more information.
Note: You can change the setting of a hex switch with a slotted-blade screwdriver that has a 3/32-inch
tip. If a hex switch setting is changed, power to the MCB must be cycled in order to enter the new
setting into memory. This can be done by turning the panel’s power switch off and then back on.
Figure 3. Hex Switches Showing 01 Setting
1
2
3
0
4
5
6
7
8
9
A
B
C
D
E
F
1
2
3
0
4
5
6
7
8
9
A
B
C
D
E
F
HI (left) hex switch LO (right) hex switch

10 IM620-1
Expansion Bus Connection
The Expansion Bus connector sends output signals to the Analog Output Expansion Module (see the
“Accessories” section) via a ribbon cable. The output signals are used by the Analog Output
Expansion Module to drive various control devices.
Communication Ports
The MCB has two communication ports: port A and port B. Each port has six terminals and is set up
for both the RS-232C and RS-485 data transmission interface standards. The male and female
connectors for these ports are manufactured by AMP. Therefore, they are referred to as “AMP plugs”
or “AMP connectors” throughout this manual. Socketed fuses located next to the ports protect the
communications drivers from voltage in excess of ±12 V. Following are brief descriptions of each
port’s function.
Port A: Port A is for communications with an absorption chiller unit controller, another
manufacturer’s BAS interface device, or an IBM compatible PC using the RS-232C
interface standard. When port A is used for communications with the absorption chiller
unit controller, the communications rate is 4800 bps with an interface standard of RS-485.
When port A connects to the BAS interface device or a PC, the communications rate is
9600 bps. The PC can be directly connected, over a limited distance, with a twisted,
shielded pair cable. For more information, see “PC Connection” in the “Field Wiring”
section of this manual.
Port B: Port B is for network communications between the MAG and the absorption chiller, or the
MAG and the level-1 MicroTech controller using the RS-485 interface standard. A twisted,
shielded pair cable should be connected to port B via terminals B+, B–, and GND on
terminal block T11. The communications rate is 9600 bps. For more information, see
“Network Communications” in the “Field Wiring” section of this manual.
Output Board
The Output Board (OB) accepts up to 24 digital outputs from the MCB. Each output has fused
sockets and can be used to drive an AC or DC load by selecting a particular relay output module.
Screw terminals allow for field wiring connections to the output device. Each output has an onboard
LED that illuminates when an output socket that contains a relay is activated by the MCB. Following
are the Output Board’s power ratings.
•120V ~ 50/60 Hz
•250V ~ 50/60 Hz
Input Conditioning Module Terminal Board
The Input Conditioning Module (ICM) Terminal is provided for possible future applications. The ICM
Terminal Board has three edge card connectors, field wiring terminals for analog and digital inputs,
field wiring terminals for 5 Vdc and 24 Vac, field wiring terminals for communication ports, and ribbon
cable connections to the MCB.
Power
Above each edge card connector are field wiring terminals for 5 Vdc (regulated) and 24 Vac (ground
referenced). These terminals can be used to power peripheral devices. It is also used to power the
LEDs in the Output Board.
Communications
Also located on the ICM Terminal Board are communications field wiring terminals. Terminals B+, B–,
and GND connect to either a level–1 controller’s communications field wiring terminals or to the
absorption chiller. Terminals A+, A–, and GND connect to the BAS integrator, the absorption chiller,
or a PC. Both sets of terminals have an AMP connector that attach to the MCB port A and port B.

IM620-1 11
Software ID
MicroTech software is factory installed and tested in each panel prior to shipment. The software is
identified by a program code (also referred to as the “Ident”). The program code is encoded in the
controller's memory and is available for display by using a PC equipped with Monitor software. The
MAG has standard software written specifically for the Direct Connect MAG and the Network
Connect MAG.
Note: A Direct Connect MAG can be changed to a Network Connect MAG by downloading the
correct program code (see Table 5) into the MCB. No additional hardware is needed to change the
Direct Connect MAG to the Network Connect MAG. If your Direct Connect MAG needs to be
changed to a Network Connect MAG, contact your McQuay Service representative.
Figure 4. Software ID Label
P/N860-654873B-50
SOFTWAREI.D.
EOSNO. 20.21
VENDORS/N 3574
VENDORMDL# 280-50
DATECODE 10-94
MCB part number
Program code ("Ident")
Table 5. Program Codes
MAG Type Program Code
Direct Connect 950468 010
Network Connect 950469 010
Accessories
The accessories of the MAG allow for additional analog outputs and digital outputs. The components
that make these additional outputs possible are the Analog Output Expansion Module (AOX-4) and
the Solid-State Relay Kit (SSR). See Table 6 for the installation manuals on the different Accessories.
Table 6. Accessory Installation Manuals
Accessory Installation Manual
Analog Output Expansion Module (AOX-4) IM 607
Solid-State Relay Kit (SSR) IM 606
Solid State Relay Kit
The Solid-State Relay Kit consists of a package of eight AC power rated relays. The relays plug into
the 24-channel Output Board (OB) in the MAG. If all channels of the OB are to be used, three relay
kits must be purchased. If other types of relays are needed, such as dry contact or dc power rated,
they can be ordered as individual units. For more information on the Solid-State Relay Kit, see Bulletin
No. IM 606.

12 IM620-1
Analog Output Expansion Module
The Analog Output Expansion Module (AOX-4) provides variable voltage or current control signals
from the MAG in order to drive various control devices. The AOX-4 is inserted into the snap track of
the MAG. Only one AOX-4 board can be ordered providing a maximum of four output channels.
Jumpers on the AOX-4 allow the user to configure the output ports to one of the following
current/voltage selections:
•0–5 Vdc
•0–10 Vdc
•0–5 mA
•0–20 mA
For more information on the Analog Output Expansion Module, see Bulletin No. IM 607.
Figure 5. Analog Output Expansion Module (AOX-4)
POWER
OK BAD
Analog Output Ports
Analog Switch
Selectors
Address Switch
J1
J7
J2 J3 J4 J5 J6
AC AC DC G -+ + +-+-
Power LEDs
26-pin Expansion Bus
Connector
26-pin Expansion Bus
Connector
-
Power Connector
a0166
MicroTech Monitoring and Networking Options
PC Monitoring
A PC (personal computer) equipped with the appropriate Monitor software can be used to provide a
high-level interface with a MicroTech network (see PC specification below). Monitor software features
a DOS-based display, multilevel password access, and advanced trend-logging. The PC can be
connected directly to the MAG. For more information on connecting the PC to the controller, refer to
“PC Connection” in the “Field Wiring” section of this manual.
For the most convenience and best operation, the PC should be considered dedicated to the
MicroTech system. However, you can exit the Monitor program to perform other tasks without
affecting equipment control. Refer to the user’s manual supplied with the Monitor software for
additional information.

IM620-1 13
PC Specification
A direct connected computer can be used for monitoring MAG Panel and unit operation. The PC must
be an IBM or 100% true compatible. Table 7 shows the preferred and minimum PC specifications.
Network Master Panel
The MicroTech Network Master Panel (NMP) allows the MAG Panel(s) and associated units to be
incorporated into a building-wide network with other MicroTech unit and auxiliary controllers. In
conjunction with a PC and Monitor software, it gives the building operator the capability to perform
advanced equipment monitoring from a central or remote location.
For further information, contact your McQuay sales representative.
Open Protocol
MicroTech Open Protocol™ provides an interface between the MAG Panel and the building
automation system of one of many participating manufacturers. With Open Protocol, the building
automation system can do the following:
•Monitor most controller setpoints, parameters, and alarms
In an Open Protocol application that includes one MAG Panel, the MicroTech Open Protocol Master
(OPM) Panel is not required because the MAG can connect directly to the BAS interface. If two or
more MAG Panels are included, the MicroTech Open Protocol Master (OPM) Panel is required. For
further information, contact your McQuay sales representative.
Table 7. PC Specification
Preferred Configuration Minimum Configuration
486DX processor, 66MHz or better 386SX processor, 16 MHz
8 MB of RAM or better 4 MB of RAM
120 MB hard disk drive or better 60 MB hard disk drive
3½” floppy disk drive 3½” floppy disk drive
Serial port (9 pin male; Com1 or Com2) Serial port (9 or 25 pin male; Com1 or Com2)
Parallel port –
Internal time clock, battery backed Internal time clock, battery backed
Super VGA graphics capability VGA graphics capability
Super VGA monitor VGA monitor
Printer –
Bus mouse or trackball Serial mouse or trackball*
101 enhanced keyboard 101 enhanced keyboard
9600 bps modem, compatible with the AT command set
(optional) 1200 bps modem, compatible with the AT command set (optional)
MS-DOS® 6.2 or higher MS-DOS® 5.0
Microsoft® Windows™ 3.1 or higher Microsoft® Windows™ 3.1
MicroTech® Monitor™ for Windows software MicroTech® Monitor™ for Windows software
* If a serial pointing device is used, there must be another serial port (Com1 or Com2) available for connecting the PC to the
MicroTech controller.

14 IM620-1
Installation
Panel Location and Mounting
The MAG panel is suitable for indoor use only. Table 8 lists the allowable temperature and humidity
ranges. Locate the panel at a convenient height, and allow adequate clearance for the door swing.
Mount the panel to the wall with screws or bolts. Four ¼-inch openings are provided at the corners of
the panel. The panel weighs approximately 60 lb. (27 kg). Figure 6 shows the panel dimensions.
The MAG Panel is equipped with special door hinges that have a friction adjustment screw. By
adjusting this screw you can prevent the panel door from swinging open or closed unexpectedly.
Table 8. MAG Panel Environmental Specifications
Panel State Temperature Relative Humidity
Operating 30 – 100°F (–1 – 38°C) 10 – 95% (noncondensing)
In storage 0 – 125°F (–18 – 52°C) 10 – 95% (noncondensing)
Figure 6. MAG Panel Dimensions
6-3/8"
15-3/8"
Bottom View
24"
Front View
Left Side View
1/4" (6.4) Dia. mounting slots (2)
Hinge friction adjustment screw
7/8" (22.3) Dia.
knockouts
24"
16"
22"
4"4"
1-7/8"
1-7/8"
4-3/4"
Right Side View
7/8" (22.3) Dia. knockouts
1-3/4"
21"
15"
12"
9"
6"
3"
10-7/8"
22-1/8"
18"
(102) (406) (102)
(610)
(48) (162)
(276.2)
(391)
(562)
(48)
(610)
(559)
(44.5)
(121)
(76)
(152)
(229)
(305)
(381)
(457)
(533)
Numbers in parenthesis = millimeters (mm)
1/4" (6.4) Dia. mounting slots (2)
a0107

IM620-1 15
Field Wiring
Following are descriptions of the various field wiring requirements and options. Typical field wiring
diagrams are shown in Figures 7 and 8. Wiring must comply with the National Electrical Code and all
local codes and ordinances. The warranty is void if wiring is not in accordance with these
instructions.
The panel is separated into high and low voltage sections. The power wiring should enter the bottom
knockout on the right side of the panel in the high voltage section. Wiring from the Output Board
should enter through one of the 7/8-inch knockouts in the high voltage section. Communications
wiring, wiring to the ICM Terminal Board, and wiring to the AOX-4 should enter through one of the
7/8-inch knockouts provided in the low voltage section.
Note: High voltage wires should not pass through the low voltage section and the low voltage wires
should not pass through the high voltage section.
Power
!
WARNING
Electric shock hazard. Can cause personal injury or death.
This equipment must be properly grounded.
All protective deadfront panels must be reinstalled and secured when power wiring is
complete.
The MAG requires a 115 Vac power supply. The supply connects to terminals L1 and L2 in the high
voltage section of the panel. The panel must be properly grounded by connecting the ground lug
(GRD) to earth ground. Refer to Figures 7 and 8. Power wiring must be sized to carry at least 5 amps.
To gain access to the high voltage section, remove the deadfront barrier. It is attached to the panel
with five 5/16-inch hex screws. Replace this deadfront when the wiring is complete.
Network Communications
For network communications to occur, a twisted, shielded pair cable must be connected between the
MAG and its associated MicroTech unit or network controllers. This interconnecting, “daisy-chain”
wiring is shown in Figures 7 and 8. Network communications is accomplished using the RS-485
interface standard at 9600 bps.
About MicroTech Network Architecture
All controllers in a MicroTech network are assigned a “level”: level 1, level 2, or level 3. All networks
must have one level-1 controller to coordinate communications. Multiple level-2 controllers connect to
the level-1 controller with a communications “trunk,” an isolated section of the daisy-chained network
wiring. In Figures 7 and 8, the network wiring between all controllers is a trunk. Multiple level-3
controllers can be connected to a level-2 controller with a separate trunk. The maximum allowable
length ofa communications trunk is 5000 feet.
Cable Specification
The network communications cable must meet the following minimum requirements: twisted, shielded
pair with drain wire, 300 V, 60°C, 20 AWG, polyethylene insulated, with a PVC outer jacket (Belden
8762 or equivalent).
Some local codes or applications may require the use of plenum rated cable. Do not install the cable
in the same conduit with power wiring.

16 IM620-1
Note: Ideally, one continuous piece of cable should connect any two controllers. This reduces the
risk of communications errors. If the cable must be spliced, use crimp-type butt connectors (good) or
solder (best). Do not use wire nuts.
Wiring Instructions-Network Connect MAG
The network connection to the Network Connect MAG is at port B on the MCB (Microprocessor
Control Board).
As shown in Figure 7, field wiring to port B can be accomplished by connecting the network cable
from terminals B+, B–, and GND in the NMP or OPM Panel to terminals B+, B–, and GND on the MAG.
Field wiring connection to port A can be accomplished by connecting the Communications Interface
Cable (CIC) from the chiller to terminals A+, A–, and GND in the MAG (see Figure 7).
Note that the unit designations (Network Connect MAG #1 and Network Connect MAG #2), are
established by the network address, not the physical position of the unit in the daisy chain. The
networked controllers can be wired in any order. For example, the NMP or OPM controller could be
connected between MAG #1 and MAG #2. It is highly recommended that the installing contractor
keep track of the physical order of the controllers on the daisy-chained trunk.This facilitates
troubleshooting any network communications problems that may occur. For more on network address,
see “Addressing the Controllers” in the “Network Commissioning” section of this manual.
Use the following procedure to perform the Network Connect wiring:
1. Before beginning, verify that port A and port B plugs are disconnected from every controller on
the communications trunk being wired. These plugs are connected during the commissioning
procedure. This is a precaution to prevent stray high voltage from damaging the controllers. Any
voltage more than 12 V can damage the board's communications drivers.
2. Connect the network cable in a daisy–chain manner as shown in Figure 7. Use caution to ensure
that the correct polarity is maintained at each controller. Be sure to connect each cable's shield to
the controllers as shown in the figure. The positive (+), negative (–), and shield (ground)
conductor must be continuous over the trunk.
3. Connect the Communications Interface Cable (CIC) to the absorption chiller. Connect the wires
from the CIC to terminals A+, A–, and GND in the MAG as shown in Figure 7.

IM620-1 17
Figure 7. Typical Field Wiring Schematic: Network Connect MAG
Port
B
MCB
MCB
Network Connect MAG #1
L1
L2 MCB
Network Connect MAG #2
L1
L2
Microprocessor Microprocessor
Absorption Chiller
Unit Controller Absorption Chiller
Unit Controller
Level-1 Controller
(eg. OPM, NMP)
Port
A
A+
A-
GND
B+
B-
GND
To Open Protocol BAS Integrator
or Personal Computer
B+ B- GND B+ B- GND
A+ A- GND
A+ A- GND
ICM Terminal
Board ICM Terminal
Board
Communications
Interface Cable Communications
Interface Cable
Hot
Neutral
Hot
Neutral
Legend
Field Wiring
Terminal Cable: Shielded,
Twisted and
Jacketed Pair
with Drain Wire
Factory Wiring Field Wiring
Line
Input
Line
Input
WHT BLK BLK
WHT
WHT
BLK
See Note
a0167
Wiring Instructions–Direct Connect MAG
The Direct Connect MAG field wiring consists of connecting the MAG to the absorption chiller
controller.
As shown in Figure 8, field wiring to port B can be accomplished by connecting the wires from the
Communications Interface Cable (CIC) to terminals B+, B–, and GND in the MAG.
Port A is used for communications with an Open Protocol BAS or connection to a PC in a MicroTech
network.

18 IM620-1
Use the following procedure to perform the Direct Connect wiring:
1. Connect the Communications Interface Cable (CIC) to the absorption chiller. Connect the wires
from the CIC to terminals B+, B–, and GND in the MAG as shown in Figure 8.
Figure 8. Typical Field Wiring Schematic: Direct Connect MAG
MCB
Direct Connect MAG
L1
L2
Microprocessor
Absorption Chiller
Unit Controller
To Open Protocol BAS Integrator
or Personal Computer
B+ B- GND
A+ A- GND
ICM Terminal
Board
Communications
Interface Cable
Hot
Neutral
Legend
Field Wiring
Terminal Cable: Shielded, Twisted and
Jacketed Pair with
Drain Wire
Factory Wiring Field Wiring
Line
Input
a0168
PC Connection
The PC is connected to any MicroTech controller at port A on the MCB. It is best to connect a PC to
a level-1 controller because faster data transmission results; however, a PC can be connected to any
level-2 controller that does not have level-3 controllers associated with it. Either way, the PC has
access to the entire network (see note below). In the typical application, the NMP is a level 1, the
MAG and other controllers are level 2. See “Network Communications” above for more on network
architecture.

IM620-1 19
Note: If a PC is connected to a level-2 controller, a level-1 controller must be set up to poll that level-2
controller so that the PC has access to the entire network. For information on how to set up the level-1
controller to poll the level-2 controller, see the operation manual for the particular controller being
used.
Direct Connection
An RS-232 communications cable kit allows a PC to directly connect to any MicroTech controller. It is
available from McQuay International. The cable has a female DB9 connector for connection to the
PC's 9-pin serial port. (If the PC has a 25-pin serial port, obtain an adapter.) The cable length is 12 feet.
If more length is required, a twisted, shielded pair cable can be spliced into the kit cable (see “Cable
Specification” below). If this is done, splice the conductors with crimp-type butt connectors (good) or
solder (best). Do not use wire nuts. The maximum allowable cable length for direct connection
between the PC and a controller is 50 feet.
Cable Specification for Direct PC Connection
A properly terminated, twisted, shielded pair cable is required to directly connect a PC to a MicroTech
controller. The cable must meet the following minimum requirements: twisted, shielded pair with drain
wire, 300 V, 60°C, 20 AWG, polyethylene insulated, with a PVC outer jacket (Belden 8762 or
equivalent). It must also be properly terminated to an AMP plug on one end and a female DB9 or
DB25 connector on the other. See Figures 9 and 10 for cable pinouts.
The DB9 or DB25 connector is for connection to a 9-pin or 25-pin serial port on the PC. Note that
some local codes or applications may require the use of plenum rated cable. Do not install the cable
in the same conduit with power wiring.
Note: A factory-assembled cable that meets the above specification is provided with the PC
Communications Cable Kit. This cable has a DB9 connector.
Figure 9. RS-232 Cable Pinouts for 9-Pin Serial Ports (AMP Connector)
SignalPin
Female DB-9
CTS8RTS7DSR6GND5DTR4TD3RD2DCD1
Signal Pin
AMP Plug
–6
GND 5
RD 3
–2
TD 1White
Black
Shield
a0109

20 IM620-1
Figure 10. RS-232 Cable Pinouts for 25-Pin Serial Ports (AMP Connector)
SignalPin
Female DB-25
DTR20 DCD8GND7DSR6CTS5RTS4RD3TD2
Signal Pin
AMP Plug
–6
GND 5
RD 3
–2
TD 1White
Black
Shield
a0110
Analog Output Connection
The MAG Panel provides analog output signals from the MCB’s Expansion Bus Connector to the
Analog Output Expansion Module (AOX-4) via a ribbon cable. The AOX-4 provides a variable
voltage or current control signal to the output devices and is powered by the MAG Panel’s 13 Vdc
power supply. Wiring to the output devices is performed at the AOX-4’s analog output ports. Each
port has a two-pin Phoenix connector with screw terminals for connection to the output device (see
“Wiring Instructions” below). For more information on the AOX-4, see Bulletin No. IM 607,
MicroTech Analog Output Expansion Module, or refer to “Analog Output Expansion Module”in the
“Accessories” section of this manual.
!
CAUTION
Ground loop current hazard. Can cause equipment damage.
The analog output signals (voltage mode) must be isolated from any ground other than the
MicroTech controller chassis ground. If it is not, ground loop currents could occur which could
damage the MicroTech controller.
Cable Specifications
The cable for the analog outputs must meet the following minimum requirements: twisted, shielded
pair with drain wire, 300 V, 60° C, 20 AWG, polyethylene insulated, with a PVC outer jacket.
Depending on the application, either two conductors (Belden 8762 or equivalent) or three conductors
(Belden 8772 or equivalent) are required.
Note that some local codes or applications may require the use of plenum rate cable. Do not install
the cable in the same conduit with power wiring.
Wiring Instructions
The following wiring instructions explain how to connect a analog output to the MAG Panel.
Use the following procedure to connect an analog output to the MAG Panel.
1. Remove power from the panel by pressing CB1 to the OFF position.
2. Connect a power wire to the 13 Vdc screw terminal in the MAG Panel and to the DC terminal (J2-
DC) on the AOX-4.
3. Connect a ground wire to the 13 Vdc GND screw terminal in the MAG and to the G terminal (J2-G)
on the AOX-4.