Carrier RTU-MP Quick setup guide

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RT TU U- -M MP P C Co on nt tr ro ol ll le er r
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In nt te eg gr ra at ti io on n G Gu ui id de e
CARRIER CORPORATION ©2011
A member of the United Technologies Corporation family · Stock symbol UTX · Catalog No. 48-50H-T-1SB · 1/27/2011

RTU-MP Controller i
Table of Contents
Introduction.................................................................................................................................................................. 1
Safety Considerations ..........................................................................................................................................3
Wiring Inputs and Outputs .......................................................................................................................................... 4
Installation ................................................................................................................................................................... 5
Communications wiring - protocols ...................................................................................................................5
Protocol Overview.................................................................................................................................. 5
Configuring the RTU-MP for BACnet MS/TP......................................................................................... 6
Configuring the RTU-MP for Modbus RTU ............................................................................................ 7
Configuring the RTU-MP for N2 ............................................................................................................ 9
LonWorks .............................................................................................................................................10
Configuring the RTU-MP for LonWorks Option Card ...............................................................10
Commissioning the RTU-MP for LonWorks communication ..................................................12
Local Access ........................................................................................................................................12
BACview6 Handheld.................................................................................................................12
Virtual BACview.........................................................................................................................13
Sequence of operation...................................................................................................................................... 13
Scheduling ...........................................................................................................................................13
Indoor Fan............................................................................................................................................15
Cooling .................................................................................................................................................15
Economizer ..........................................................................................................................................16
Power Exhaust .....................................................................................................................................17
Heating.................................................................................................................................................17
Indoor Air Quality .................................................................................................................................18
Dehumidification .................................................................................................................................18
Demand Limiting .................................................................................................................................19
Troubleshooting .........................................................................................................................................................20
LED's .................................................................................................................................................................... 20
BACnet MSTP ..................................................................................................................................................... 21
Modbus................................................................................................................................................................ 23
Johnson N2 ......................................................................................................................................................... 23
LonWorks ............................................................................................................................................................ 24
Compliance ................................................................................................................................................................25
FCC Compliance................................................................................................................................................. 25
CE Compliance ................................................................................................................................................... 25
BACnet Compliance........................................................................................................................................... 25
Appendix A- Network Points List for the RTU-MP....................................................................................................26
Appendix B - BACnet Protocol Implementation Conformance Statement ...........................................................32
BACnet Data Link Layer Options ..................................................................................................................... 33
Analog Input.........................................................................................................................................34
Analog Output......................................................................................................................................34
Analog Value (PAR)..............................................................................................................................35
Analog Value (RS)................................................................................................................................36
Analog Value (STAT) ............................................................................................................................36
Binary Input .........................................................................................................................................37
Binary Output.......................................................................................................................................37
Binary Value (PAR), (CLOCK), and (STAT)...........................................................................................38
Binary Value (PAR), (CLOCK), and (STAT)...........................................................................................39
Binary Value (MODULE ALARM)..........................................................................................................40
Calendar ..............................................................................................................................................40

Table of Contents
ii RTU-MP Controller
Device ..................................................................................................................................................40
File........................................................................................................................................................41
Multi_State Value................................................................................................................................42
Multi_State Value (STAT) ....................................................................................................................42
Notification Class ................................................................................................................................43
Program ...............................................................................................................................................43
Schedule..............................................................................................................................................43
Trend_log .............................................................................................................................................44
Appendix D: Johnson Controls N2 Protocol Implementation Conformance Statement.....................................45
Appendix C: Modbus Protocol Implementation Conformance Statement...........................................................47
Appendix E: LonWorks Protocol Implementation Conformance Statement .......................................................49
Index ...........................................................................................................................................................................51

RTU-MP Controller 1
The RTU-MP controller was custom designed to be an integrated component of a Carrier rooftop unit. Its
internal application programming provides optimum performance and energy efficiency.
RTU-MP enables the unit to run in a 100% stand-alone control mode (using space temperature and/or
humidity sensors are not required), or it can communicate to the Building Automation System (BAS). On-board
DIP switches allow you choose your protocol and baud rate; BACnet, Modbus, Johnson N2 or LonWorks.
This document will serve as the reference guide for integrating RTU-MP into the BAS. It should be read
thoroughly, understood, and all functions performed by the group installing or commissioning the BAS.
Failure to follow this warning could cause personal injury, death, and/or equipment damage.
ELECTRICAL SHOCK HAZARD
Disconnect all power to the unit before performing maintenance or service. Unit may automatically start if
power is not disconnected.
Introduction

Introduction
2 RTU-MP Controller

RTU-MP Controller 3
Safety Considerations
Installation and servicing of air-conditioning equipment can be hazardous due to system pressure and
electrical components. Only trained and qualified service personnel should install, repair, or service air-
conditioning equipment.
Untrained personnel can perform the basic maintenance functions. All other operations should be performed
by trained service personnel. When working on equipment, observe precautions mentioned in the literature,
tags, and labels attached to the unit, and other safety precautions that may apply.
Follow all safety codes. Wear safety glasses and work gloves. Recognize safety information.
This is the safety-alert symbol . When you see this symbol on the unit, in the instructions or manuals, be
alert to the potential for personal injury.
Understand the signal words DANGER, WARNING, and CAUTION. These words are used with the safety-alert
symbol.
•DANGER identifies the most serious hazards which will result in severe personal injury or death.
•WARNING signifies a hazard which could result in personal injury or death.
•CAUTION is used to identify unsafe practices which may result in minor personal injury or product and
property damage.
•NOTE is used to highlight suggestions which will result in enhanced installation, reliability, or operation.
Failure to follow this warning could cause personal injury, death, and/or equipment damage.
ELECTRICAL SHOCK HAZARD
Disconnect all power to the unit before performing maintenance or service. Unit may automatically start if
power is not disconnected.

Wiring Inputs and Outputs
4 RTU-MP Controller
RTU-MP Inputs and Outputs Table
Point Name
BACnet
Object
Name
Type of I/O
Connection Pin
Numbers
Space Temperature Sensor
Inputs
sptsens AI (10K Thermistor) J20 - 1, 2
Supply Air Temperature sat AI (10K Thermistor) J2 - 1, 2
Local Outside Air Temperature Sensor oatsens AI (10K Thermistor) J2 - 3, 4
Space Temperature Offset Pot
sptopot
AI (100K Potentiometer)
J2 - 3, 4
Indoor Air Quality iaq AI (4 - 20 ma) J4 - 2, 3
Outdoor Air Quality oaq AI (4 - 20 ma) J4 - 5, 6
Safety Chain Feedback safety DI (24 VAC) J1 - 9
Compressor Safety compstat DI (24 VAC) J1 - 2
Fire Shutdown firedown DI (24 VAC) J1 - 10
Enthalpy Switch enthalpy DI (24 VAC) J2 - 6, 7
Humidistat Input Status humstat DI (24 VAC) J5 - 7, 8
Space Relative Humidity
Configurable Inputs
sprh AI (4-20 ma) J4 - 2,3 or J4 - 5,6
Outside Air Relative Humidity
oarh
AI (4-20 ma)
J4 - 2,3 or J4 - 5,6
Supply Fan Status fanstat DI (24 VAC) J5 - 1,2 or J5 - 3,4 or J5 5,6
or J5 - 7,8
Filter Status filstat DI (24 VAC) J5 - 1,2 or J5 - 3,4 or J5 5,6
or J5 - 7,8
Remote Occupancy Input remocc DI (24 VAC) J5 - 1,2 or J5 - 3,4 or J5 5,6
or J5 - 7,8
Economizer Commanded
Outputs
Position
econocmd 4-20ma J2 - 5
Supply Fan Relay State sf DO Relay (24VAC , 1A) J1 - 4
Compressor 1 Relay State comp_1 DO Relay (24VAC , 1A) J1 - 8
Compressor 2 Relay State comp_2 DO Relay (24VAC , 1A) J1 - 7
Heat Stage 1 Relay State heat_1 DO Relay (24VAC , 1A) J1 - 6
Heat Stage 2 Relay State heat_2 DO Relay (24VAC , 1A) J1 - 5
Power Exhaust Relay State aux_2 DO Relay (24VAC , 1A) J1 - 3
Dehumidification Relay State humizer DO Relay (24VAC , 1A) J1 - 7, 8
Legend
AI
-Analog Input
AO
- Analog Output
DI
-Digital Input
DO
*These inputs (if installed) take the place of the default input on the specific channel according to schematic. Parallel pins J5
- 1 = J2 - 6, J5 - 3 = J1 - 10, J5 - 5 = J1 - 2 are used for field installation.
- Digital Output
Refer to the input configuration and accessory sections, unit Controls Operation, and Troubleshooting Instructions.
Wiring Inputs and Outputs

RTU-MP Controller 5
Communications wiring - protocols
Protocol Overview
Protocols are the communication languages spoken by control devices. The main purpose of a protocol is to
communicate information in the most efficient method possible. Different protocols exist to provide different
kinds of information for different applications.
In the BAS application, many different protocols are used, depending on manufacturer. Different protocols do
not change the function of the controller, but, they typically require the owner to change systems or
components in order to change from one protocol to another. The RTU-MP is an effective solution to minimize
the amount of equipment change necessary to communicate with different protocols. Currently, the four most
common protocols are: BACnet, Modbus, N2, and LonWorks.
The RTU-MP can be set to communicate using one of four different protocols: BACnet, Modbus, N2, or
LonWorks. The default setting is BACnet. Switch 3 (SW3) on the board is used to set protocol and baud rate.
Switches 1 and 2 (SW1 and SW2) are used to set the board’s network address. See the table below for the
specific switch settings. The 3rd party connection to the RTU-MP is through port J19 for BACnet, Modbus, and
N2, and through J15 for the LonWorks Option Card.
NOTES
○Changing protocol requires no programming or point assignment by the installer or operator.
○Power must be cycled after changing the SW1 - SW3 settings.
SW3 Switch Settings Table
Protocol Selection
Baud Rate
Protocol
DS8
DS7
DS6
DS5
DS4
DS3
DS2
DS1
BACnet MS/TP
(Default)
Unused
Master
Off Off Off On Off Select
Baud
Select
Baud
Modbus
Unused
Slave
Off Off On On Off Select
Baud
Select
Baud
N2
Unused
Slave
Off Off Off On On Off Off
Lonworks
Unused On On Off On Off Off On
Baud Selection Table
Baud Rate
SW3/DS2
SW3/DS1
Off
9,600
Off
On
19,200
Off
Off
38,400
On
76,800
On
(Default)
On
Installation

Installation
6 RTU-MP Controller
Configuring the RTU-MP for BACnet MS/TP
Refer to Appendix B of this document for the Protocol Implementation Conformance Statement, or download
the latest from http://www.bacnetassociation.org/BMAProductCatalog/Carrier/.
1 Turn off the RTU-MP's power.
NOTE Changes made to the switches when the RTU-MP is on will not take effect until the RTU-MP has
been power cycled!
2 Using the rotary switches SW1 and SW2, set a unique MS/TP MAC address for the RTU-MP. Set the
MSB (SW1) switch to the tens digit of the address, and set the LSB (SW2) switch to the ones digit. Valid
addresses are 01-99.
NOTE The rotary switches also determine the BACnet device instance of the controller on the BACnet
network. The BACnet device instance is automatically generated based on the scheme 1600xx, where
“16” is the BACnet vendor ID for Carrier Carrier Corporation, and xx equals the rotary switch address.
EXAMPLE To set the RTU-MP’s MS/TP MAC address to 01, point the arrow on the MSB (SW1) switch to
0 and the arrow on the LSB (SW2) switch to 1. Internally, the BACnet device instance is automatically
generated as 160001.
3 Set the SW3 Comm Selector DIP switches DS1 and DS2 for the appropriate communications speed
(9600, 19.2k, 38.4k, or 76.8k bps).
NOTE Use the same baud rate and communication settings for all controllers on the network segment.
The RTU-MP is fixed at 8 data bits, No Parity, and 1 Stop bit for this protocol's communications.
Baud Selection Table
Baud Rate
SW3/DS2
SW3/DS1
9,600
Off Off
19,200
On Off
38,400
Off On
76,800
On On
4 Set SW3 Comm Selector DIP switches DS3 through DS6 for BACnet MS/TP. See table and example
below.
5 Leave DS7 and DS8 in the OFF position. These switches are not applicable to MS/TP.
SW3 Protocol Switch Settings for MS/TP
DS8
DS7
DS6
DS5
DS4
DS3
Off Off Off Off On Off

RTU-MP Controller 7
The following example shows the DIP Switches set for 38.4k, and MS/TP.
6 Connect the MS/TP network to the RTU-MP's J19 port. Connect to Net+, Net-, and SHLD.
Wire specifications
○A dedicated 22 AWG to 18 AWG twisted pair wire (EIA 485)
○2000 feet (610 meters) for 76.8 kbps
○Devices should be daisy chained and not star wired
○Attach a shield at the beginning or end of the network segment and not at every controller
NOTE Use the same polarity throughout the network segment.
7 Turn on the RTU-MP's power.
Configuring the RTU-MP for Modbus RTU
Refer to Appendix C of this document for the Modbus Protocol Implementation Conformance Statement
(PICS).
1 Turn off the RTU-MP's power.
NOTE Changes made to the switches when the RTU-MP is on will not take effect until the RTU-MP has
been power cycled!
2 Using the rotary switches, set a unique Modbus slave address for the RTU-MP. Set the MSB (SW1) switch
to the tens digit of the address, and set the LSB (SW2) switch to the ones digit. Valid Modbus slave
addresses are 01-99.
EXAMPLE To set the RTU-MP’s Modbus slave address to 01, point the arrow on the MSB (SW1) switch to
0 and the arrow on the LSB (SW2) switch to 1.

Installation
8 RTU-MP Controller
3 Set the SW3 Comm Selector DIP switches DS1 and DS2 for the appropriate communications speed
(9600, 19.2k, 38.4k, or 76.8k bps).
NOTE Use the same baud rate and communication settings for all controllers on the network segment.
The RTU-MP is fixed at 8 data bits, No Parity, and 1 Stop bit for this protocol's communications.
Baud Selection Table
Baud Rate
SW3/DS2
SW3/DS1
9,600
Off Off
19,200
On Off
38,400
Off On
76,800
On On
4 Set SW3 Comm Selector DIP switches DS3 through DS6 for Modbus. See example below.
5 Leave DS7 and DS8 in the OFF position. These switches are not applicable to Modbus.
SW3 Protocol Switch Settings for Modbus
DS8
DS7
DS6
DS5
DS4
DS3
Off Off Off On On Off
The following example shows the DIP Switches set for 9600 baud and Modbus.
6 Connect the Modbus EIA-485 network to the RTU-MP's J19 port. Connect to Net+, Net-, and SHLD.
Wire specifications
○A dedicated 22 AWG to 18 AWG twisted pair wire (EIA 485)
○2000 feet (610 meters) for 76.8 kbps
○Devices should be daisy chained and not star wired
○Attach a shield at the beginning or end of the network segment and not at every controller
NOTE Use the same polarity throughout the network segment.
7 Turn on the RTU-MP's power.

RTU-MP Controller 9
Configuring the RTU-MP for N2
Refer to Appendix D of this document for the N2 Protocol Implementation Conformance Statement (PICS).
1 Turn off the RTU-MP's power.
NOTE Changes made to the switches when the RTU-MP is on will not take effect until the RTU-MP has
been power cycled!
2 Using the rotary switches, set a unique N2 slave address for the RTU-MP. Set the MSB (SW1) switch to
the tens digit of the address, and set the LSB (SW2) switch to the ones digit. Valid N2 slave addresses
are 01-99.
EXAMPLE To set the RTU-MP’s N2 slave address to 01, point the arrow on the MSB (SW1) switch to 0
and the arrow on the LSB (SW1) switch to 1.
3 Set the Comm Selector DIP switches DS1 and DS2 for the 9600 baud.
NOTE Use the same baud rate and communication settings for all controllers on the network segment.
TheRTU-MP is fixed at 9600 baud, 8 data bits, No Parity, and 1 Stop bit.
4 Set SW3 Comm Selector DIP switches DS3 through DS6 for N2. See example below.
5 Leave DS7 and DS8 in the OFF position. These switches are not applicable to N2.
SW3 Protocol Switch Settings for N2
DS8
DS7
DS6
DS5
DS4
DS3
Off Off Off Off On On
The following example shows the DIP Switches set for 9600 baud and N2.
6 Connect the N2 EIA-485 network to the RTU-MP's J19 port. Connect to Net+, Net-, and SHLD.

Installation
10 RTU-MP Controller
Wire specifications
○A dedicated 22 or 24 AWG shielded twisted pair wire (EIA 485)
○Maximum wire length 2000 feet (610 meters) or 32 nodes
○Devices should be daisy-chained and not star-wired
○Attach the drain/shield wire to both ends of the network segment and through every controller
NOTE Use the same polarity throughout the network segment.
7 Turn on the RTU-MP's power.
LonWorks
When you handle the LonWorks Option Card:
•Do not contaminate the printed circuit board with fingerprints, moisture, or any foreign material.
•Do not touch components or leads.
•Handle the board by its edges.
•Isolate from high voltage or electrostatic discharge.
•Ensure that you are properly grounded.
Refer to Appendix E (page 49) for the LonWorks Protocol Implementation Conformance Statement (PICS).
Configuring the RTU-MP for LonWorks Option Card
1 Turn off the RTU-MP's power.
NOTES
○Changes made to the switches when the RTU-MP is on will not take effect until the RTU-MP has
been power cycled!
○The controller’s rotary address switches are not used when the LON-OC is installed. That’s because
each LON-OC has a 48-bit Neuron ID that makes it unique on the LonWorks network.

RTU-MP Controller 11
2 Set the Comm Selector DIP Switches DS1 and DS2 on SW3 for 38.4k Communications speed. This is
the speed at which the LON-OC speaks to the RTU-MP. It is fixed at 38.4k.
3 Set the Comm Selector DIP Switches DS3 through DS6 on SW3 for LonWorks. See example below.
4 Set the Comm Selector DIP Switch DS7 on SW3 to the ON position to enable the LON-OC.
5 Leave Comm Selector DIP Switch DS8 on SW3 in the OFF position since it is not used.
SW3 Protocol Switch Settings for LonWorks
DS8
DS7
DS6
DS5
DS4
DS3
Off On On Off On Off
The following example shows the DIP Switches set for 38.4k baud and the LON-OC enabled.
6 Plug the LON-OC's ribbon cable into Comm Option Port J15 on the RTU-MP. See illustration below.
CAUTION! The controller must be OFF before being connected.
7 Turn on the RTU-MP's power.
8 Commision the RTU-MP for LonWorks communication. See instructions below.

Installation
12 RTU-MP Controller
Commissioning the RTU-MP for LonWorks communication
Before a device can communicate on a LonWorks network, it must be commissioned. Commissioning allows
the system integrator to associate the device hardware with the LonWorks system’s network layout diagram.
This is done using the device’s unique Neuron ID.
A network management tool such as Echelon’s LonMaker is used to commission each device, as well as to
assign addressing. Specific instructions regarding the commissioning of LonWorks devices should be
obtained from documentation supplied with the LonWorks Network Management Tool.
When a new device is first commissioned onto the LonWorks network, the system integrator must upload the
device’s External Interface File (XIF) information. LonWorks uses the XIF to determine the points (network
variables) that are available from a device. The RTU-MP has a set of predefined network variables. These
variables can be bound or accessed by the network management tool.
NOTE Contact your local Carrier representative for a copy of the .XIF file.
The Browse feature of the Network Management Tool also allows you to read real-time values from the RTU-
MP. The Network Management Tool allows you to test integration prior to binding the RTU-MP’s network
variables to other LonWorks nodes.
Local Access
BACview6 Handheld
The BACview6 Handheld (BV6H) is a keypad/display interface used to connect to the RTU-MP to access the
control information, read sensor values, and test the RTU-MP. This is an accessory interface that does not
come with the RTU-MP and can only be used at the unit.
Connect the BACview6 to the RTU-MP’s J12 local access port.
There are 2 password-protected levels in the display (User and Admin).
•The User password is defaulted to 0000 but can be changed.
•The Admin password is 1111 and cannot be changed.
NOTES
○To adjust the contrast of the display, turn the contrast screw on top of the BACview6 clockwise to
lighten the display or counterclockwise to darken it.
○There is a 10 minute auto logout if a screen is left idle.

RTU-MP Controller 13
Virtual BACview
Virtual BACview is a freeware software application that mimics the BACview6 Handheld. The USB Link cable
(USB-L) is required to connect a computer to the RTU-MP board. The USB Link cable connects a PC's USB port
to the J12 local access port on the RTU-MP. This program functions and operates identical to the BACview
Handheld.
Sequence of operation
The RTU-MP will control the compressor, economizer, and heating outputs based on its own space
temperature input and setpoints. An optional CO2 IAQ sensor mounted in the space can influence the
economizer minimum position.
The RTU-MP has its own hardware clock that is set automatically when the software is installed on the board.
The default is to control to occupied setpoints all the time, until a type of occupancy control is set. Occupancy
types are described in the scheduling section.
The following sections describe the operation for the functions of the RTU-MP. All point objects that are
referred to in this sequence will be in reference to the objects, as viewed in BACview6 Handheld.
Scheduling
Scheduling is used to start heating or cooling (become occupied), based upon a day of the week and a time
period and control to the occupied heating or cooling setpoints. Scheduling functions are located under
occupancy determination and the schedule menu accessed by the Menu softkey. Your local time and date
should be set for these functions to operate properly.

Installation
14 RTU-MP Controller
Five scheduling functions are available by changing the Occupancy Source to one of the following selections:
The unit will run continuously. This is the default configuration.
Always occupied
The unit will operate according to the schedule configured and stored in it. The local schedule is made up
of three hierarchy levels that consist of: 2 Override, 12 Holiday, and 4 Daily schedules. These are only
accessible by the BACview6 (BV6H) screen (handheld or virtual).
Local schedule
The Daily schedule is the lowest schedule in the hierarchy and is overridden by both the Holiday and
Override schedule. It consists of a start time, a stop time (both in 24 hour format), and 7 days of the
week, starting with Monday and ending with Sunday.
To select a Daily schedule,
1. Scroll to the Schedules menu from the Menu selection.
2. Enter the User password and change the Occupancy Source to Local Schedule.
3. Scroll down and over to the Daily menu and press Enter.
4. Press the Next softkey to choose one of the four Daily schedules.
5. Change the Use? point from NO to YES by selecting the point and pressing the INCR or DECR softkey.
6. Press the OK softkey and scroll to the start and stop times.
7. Edit these times following Steps 5 and 6.
8. Scroll down to Days section and highlight the days required for the Daily schedule by INCR or DECR
softkeys.
9. Press the OK softkey.
The Holiday schedule is created to override the Daily schedule and identify a specific day and month of
the year to start and stop the unit and to change control to the unoccupied heating and cooling
setpoints.
1. Follow the above steps to turn on one of the 12 Holiday schedules and the start and stop times.
2. Select 1 of the 12 months and 1 of the 31 days of that month.
The RTU-MP will now ignore the Daily schedule for the specific day and time you selected and follow the
Holiday Schedule for this period.
The Override schedule provides a temporary change in the occupied heating and cooling setpoints and
forces the unit to the unoccupied heating and cooling setpoints. This would occur on a designated day
and month and last during the start and stop time configured. The Override schedule is enabled by
following the same steps as creating the Holiday schedule.
NOTE Push button override is only available when running a local or BACnet Schedule.
For use when a Building Automation System that supports native BACnet scheduling is scheduling the
unit. With the Occupancy Source set to BACnet schedule, the BAS will control the unit through network
communication and it’s own scheduling function.
BACnet schedule

RTU-MP Controller 15
The BAS is scheduling the unit via an On/Off command to the BAS ON/OFF software point. The Building
Automation System can be speaking BACnet, Modbus, or N2 and is writing to the BAS On/Off point in the
open protocol point map.
BAS On/Off
A hard-wired input on the RTU-MP will command the unit to start/stop. Inputs 3, 5, 8, and 9 on plug J5
can be hard-wired to command the unit to start/stop.
DI On/Off
NOTE Scheduling can either be controlled via the unit or the BAS, but NOT both.
Indoor Fan
The indoor fan will be turned on whenever any one of the following conditions is true:
•It is in the occupied mode - this will be determined by its own internal occupancy schedule
•Whenever there is a demand for cooling or heating in the unoccupied mode
•Whenever the remote occupancy switch is closed during DI On/Off schedule type or if occupancy is
forced occupied by the BAS during BAS On/Off schedule type.
When transitioning from unoccupied to occupied, there will be a configured time delay of 5 to 600 seconds
before starting the fan. The fan will continue to run as long as compressors, heating stages, or the
dehumidification relays are on when transitioning from occupied to unoccupied, with the exception of
Shutdown mode.
If Fire Shutdown, safety chain, SAT alarm or SPT alarm are active, the fan will be shutdown immediately,
regardless of the occupancy state or demand.
The RTU-MP does not include controls/algorithms for additional building smoke-control functions such as
smoke-purge, zone-pressurization or smoke-ventilation. Each of these requires a field-designed circuit to
input the proper signals to the RTU-MP and to operate the following, as required by local fire codes:
•de-activation of smoke alarm signal
•RTU Indoor Fan
•RTU economizer
•RTU power exhaust
The RTU-MP has an optional Supply Fan Status input to provide proof of airflow. If this is enabled, the point
will look for a contact closure whenever the Supply Fan Relay is on. If it is not enabled, then it will always be
the same state as the Supply Fan Relay. The cooling, economizer, heating, dehumidification, CO2 and power
exhaust routines will use this input point for fan status.
Cooling
The compressor outputs are controlled by the Cooling Control PID Loop and Cooling Stages Capacity
algorithm. They will be used to calculate the desired number of stages needed to satisfy the space by
comparing the Space Temperature (SPT) to the Occupied Cool Setpoint, plus the T56 slider offset, when
occupied and the Unoccupied Cool Setpoint (UCSP), plus the T56 slider offset, if unoccupied. The economizer,
if available, will be used for cooling in addition to the compressors.
The following conditions must be true in order for this algorithm to run:
•Indoor Fan has been ON for at least 30 seconds

Installation
16 RTU-MP Controller
•Heat mode is not active and the time guard between modes equals zero
•If occupied and the SPT >(occupied cool setpoint plus the T56 slider offset)
•Space Temperature reading is available.
•If it is unoccupied and the SPT > (unoccupied cool setpoint plus the T56 slider offset). The indoor fan will
be turned on by the staging algorithm
•If economizer is available and active, and economizer open > 85% and SAT > (SAT low limit + 5°F) and
SPT > effective set point + 0.5°F.
○OR Economizer is available, but not active
○OR Economizer is not available
•OAT > DX Lockout temperature
If all of the above conditions are met, the compressors will be energized as required, otherwise they will be
de-energized.
There is a fixed 3 minute minimum on time and a 5 minute off time for each compressor output, as well as a
3 minute minimum time delay between staging up or down.
Any time the compressors are running, the RTU-MP will stage down the compressors if the SAT becomes less
than the cooling low supply air setpoint. After a compressor is staged off, it may be started again after a
normal time--guard period and the supply air temperature has increased above the low supply air setpoint.
After a compressor is staged off, it may be started again after a normal time-guard period and the supply air
temperature has increased above the low supply air setpoint.
Economizer
The Economizer dampers are used to provide free cooling and Indoor Air Quality, if optional CO2 sensor is
installed, when the outside conditions are suitable.
The following conditions must be true for economizer operation:
•Indoor Fan has been on for at least 30 seconds. S Enthalpy is Low if the Enthalpy input is enabled.
•SAT reading is available.
•OAT reading is available.
•SPT reading is available.
•OAT <= High OAT economizer lockout configuration (default = 75)
•OAT <= SPT
If any of the mentioned conditions are not true, the economizer will be set to its configured minimum
position. The minimum damper position can be overridden by the IAQ routine described later in this section.
If the above conditions are true, the Economizer Control Master Loop will calculate a damper position value
based on the following calculation:
Damper Position = minimum position + PID (SPT - econ setpoint). Econ setpoint is half way between the
effective cool and heat setpoints. If the SAT drops below the cooling low supply air setpoint (+ 5°F), the
economizer will ramp down to minimum position.