Bryant 548J User Manual

Page 65

are restored and phase sequence is correct. If no 24-v
control power is available to the PMR, the red LED will
be off.

RTU--MP 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 CO

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 RTU--MP’s 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 BACview

Handheld.

Scheduling
Scheduling is used to start heating or cooling (become

occupied) based upon a day of 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 (see Form 48--50H--T--2T, Appendix -- for

menu structure). Your local time and date should be set

for these functions to operate properly. Five scheduling

functions are available by changing the Occupancy Source

to one of the following selections:
Always Occupied (Default Occupancy)
The unit will run continuously. RTU--MP ships from the

factory with this setting.
Local Schedule
The unit will operate according to the schedule configured

and stored in the unit. The local schedule is made up of

three hierarchy levels that consist of two Override

schedules, twelve Holiday and four Daily schedules, and

are only accessible by the BACview screen (handheld or

virtual).
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 mode) and the seven days of the week, starting with

Monday and ending in Sunday. To select a daily schedule

scroll to the Schedules menu off of the Menu selection.

Enter the User password and change the Occupancy

Source to Local Schedule. Scroll down and over to the

Daily menu and press enter. Choose one of the four Daily

schedules by pressing the Next softkey and change the

Use? point from NO to YES by selecting the point and

pressing the INCR or DECR softkey. Press the OK softkey

and scroll to the start and stop times. Edit these times

following the same steps as the Use? point. Finally scroll

down to the Days: section and highlight the days required

for the Daily schedule by INCR or DECR softkeys and

press 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 change control to the

unoccupied heating and cooling setpoints. Follow the

same steps to turn on one of the twelve Holiday schedules

and start and stop times. Next, select one out of the twelve

months and one out of the thirty--one 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 schedules primary purpose is to provide a

temporary change in the occupied heating and cooling

setpoints and force the unit to control to the unoccupied

heating and cooling setpoints. This would occur on a set

day in a particular month and last during the start and stop

time configured. The Override schedule is enabled by

following the same steps to create the Holiday schedule.
NOTE: Push button override is only available when
running a local or BACnet Schedule.
BACnet Schedule
For use with 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.
BAS On/Off
The Building Automation System 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.
NOTE:

If the BAS supports NATIVE BACnet

scheduling, then set the Occupancy Source to BACnet
schedule. If the BAS is BACnet but does NOT support
NATIVE BACnet scheduling, then set the Occupancy

Source to BAS On/Off.
DI 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.
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 has an optional Supply Fan Status input to

provide proof of airflow. If this is enabled, the point will

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