Danfoss AK2-SC 255 User manual

REFRIGERATION AND
AIR CONDITIONING
AK2-SC 255
Reference Manual
Users Manual

RS.8D.M1.22 AK2-SC 255 Reference Manual 1
AK2-SC 255 Rack Controller
System Reference Manual

2 AK2-SC 255 Reference Manual RS.8D.M1.22

RS.8D.M1.22 AK2-SC 255 Reference Manual 3
AK2-SC 255 Rack Controller
System Reference Manual
What this manual
covers This manual covers configuration and operation of the Danfoss AK2-SC 255 Rack
Controller and systems based upon it. In this manual we very often refer to the
controller as “SC 255,’ a shortened version of its official name.
This manual is intended for the user who requires detailed information about any
aspect of the controller’s operation and software.
Although the manual does not at this time have an index, the Table of Contents that
follows this page is quite extensive and should be a useful guide to the text.
Other manuals for
this system Other Danfoss manuals that you should have are the On Site Guide for the AK2-SC
255, which covers installation and start-up of the controller, and theAK2 I/O Module
manual, which details installation and operation of the I/O modules and their software
interface using the AK2-SC 255 and earlier controllers.
If you can, you should check the Danfoss web site at www.acr.danfoss.com and
select the menu item for product literature. TheAK2-SC 255 literature will be in the
Supermarket electronics section.
DISCLAIMER Where this manual discusses control and monitoring of equipment not manufactured
by Danfoss, or discusses interface to software not published by Danfoss, the accu-
racy of the text is in some cases dependent upon information furnished by the manu-
facturers of such non-Danfoss products, and Danfoss cannot be held responsible for
the accuracy of lthe information. Nevertheless, we have made every effort to ascer-
tain correct information from all parties invol
Copyright ©1999,2003,2004,2005DanfossInc.Allrightsreserved.
At Danfoss, continuous improvement to documentation goes hand-in-hand
with the product refinement and quality for which Danfoss is justifiably world
famous. We welcome your suggestions for additions or improvements to any
of our manuals or other literature. Please address your comments to:
Danfoss Inc.
Literature Department
7941 Corporate Drive
Baltimore,MD 21236-4925
Telephone:[phone]
FAX: [phone]

4 AK2-SC 255 Reference Manual RS.8D.M1.22
Table of Contents
PARTONE Configuration
1.1 Initial Configuration ........................................................................................................11 - 12
Introduction ..................................................................................................................................... 11
Battery ..................................................................................................................................... 11
Authorization codes .............................................................................................................................. 11 - 12
Using Menus ..................................................................................................................................... 12
Selection of units and languages ................................................................................................................. 12
1.2 Configuring Refrigeration............................................................................................. 13 - 63
Starting with a partially configuredAK2-SC 255 ........................................................................................ 13
Starting with a completely un-configuredAK2-SC 255 .............................................................................. 14
Navigation and making changes.................................................................................................................. 14
Enteringnumerals ..................................................................................................................................... 14
Enteringlabels ..................................................................................................................................... 14
Constrainedfields .............................................................................................................................. 14 - 15
Configuring Rack Info..........................................................................................................................15 - 16
Adding a rack ..................................................................................................................................... 16
ConfiguringSuction Info ......................................................................................................................16 - 19
Configuring two-stage systems ...................................................................................................... 19 - 20
Configuringcompressors......................................................................................................................20 - 22
Compressor oil and safety information...........................................................................................22 - 23
Neutral Zone control ............................................................................................................................. 23
Compressor capacity staging patterns ...........................................................................................24 - 25
ConfiguringEvaporators ......................................................................................................................25 - 31
Case lights button .................................................................................................................................. 27
ConfiguringAK2-SC 255 refrigeration circuits..................................................................................... 28
Configuringdefrost 32 - 33
Configuringevaporators .......................................................................................................................33 - 34
Configuring condensers ........................................................................................................................34 - 46
Aircooled condensers.....................................................................................................................35 - 42
Split condenser control .............................................................................................................39 - 40
Reaction zone and time................................................................................................................... 40
Enviroguard systems ......................................................................................................................41 - 42
Evaporative condensers .................................................................................................................42 - 47
Pump, louver, and sump schedules...........................................................................................44 - 45
Inverter settings; freeze protection; dump valve......................................................................45 - 46
Dump schedules.......................................................................................................................46 - 47
Receiver configuration ................................................................................................................................ 47
Heat reclaim configuration ...................................................................................................................47 - 49
Refrigeration alarms configuration .......................................................................................................49 - 50
Board & Points configuration...................................................................................................................... 50
Navigation ..................................................................................................................................... 51
Board & Points, relay outputs (digital outputs) ..............................................................................51 - 52
Board & Points, sensor inputs (analog inputs) ...............................................................................52 - 54
Board & Points, on-off inputs (digital inputs).................................................................................54 - 55

RS.8D.M1.22 AK2-SC 255 Reference Manual 5
Board & Points, variable outputs (analog outputs)...................................................................................... 56
Board & Points, other controllers (case controllers, VFDs, etc., that are on the 255 network) ..........57 - 62
AKC 16x circuits, board & points........................................................................................................ 57
Network re-scan and initialization ................................................................................................... 58
Navigation ..................................................................................................................................... 58
EKC circuits, board & points .........................................................................................................58 - 60
Network re-scan and initialization ............................................................................................59 - 60
Wink ..................................................................................................................................... 60
Degree Master board & points ......................................................................................................60 - 61
Locate procedure ............................................................................................................................ 61
Activating the service pin from the display .....................................................................................61
Initialization ..................................................................................................................................... 61
Wink ..................................................................................................................................... 61
VLT and AKD drives, board & points...........................................................................................61 - 62
DCU circuits, board & points ............................................................................................................... 62
1.3 Configuring HVAC ..........................................................................................................63 - 113
Introduction63 - 64
RTU Configuration ..............................................................................................................................64 - 76
RTU fan configuration ...................................................................................................................64 - 66
RTU coolingconfiguration .............................................................................................................66 - 69
RTU heating configuration .............................................................................................................69 - 72
RTU dehumidificationconfiguration...............................................................................................72 - 75
RTU air damper configuration .......................................................................................................75 - 76
RTU alarms configuration ..................................................................................................................... 76
RTU board & points configuration........................................................................................................ 76
AHU Configuration ..............................................................................................................................76 - 80
AHU fan configuration ..................................................................................................................76 - 78
AHR outside air coil configuration .................................................................................................79 - 80
RTC Configuration ..............................................................................................................................80 - 93
RTC fan configuration....................................................................................................................80 - 83
RTC coolingconfiguration..............................................................................................................83 - 84
RTC heating configuration .............................................................................................................85 - 86
RTC dehumidificationconfiguration ...............................................................................................86 - 87
RTC air damper configuration........................................................................................................87 - 89
RTC schedules ..................................................................................................................................... 89
RTC alarm configuration ....................................................................................................................... 89
RTC I/O points configuration .........................................................................................................89 - 92
Relay outputs (digital outputs) ......................................................................................................... 90
Sensor inputs (analog inputs) ...................................................................................................90 - 91
On-offinputs (digital inputs) ....................................................................................................91 - 92
RTC I/O variable outputs (analog outputs) ..............................................................................92 - 93
RTC address and Initialization........................................................................................................93 - 94
Seasons 4 Smart Coil configuration......................................................................................................94 - 98
Fan configuration, Seasons 4 Smart Coil............................................................................................... 94
Cooling configuration, Seasons 4 Smart Coil..................................................................................95 - 96
Heating configuration, Seasons 4 Smart Coil ................................................................................. 96 - 97
Dehumidification configuration, Seasons 4 Smart Coil...................................................................98 - 99
Condenser configuration, Seasons 4 Smart Coil ...................................................................................99
Alarms configuration, Seasons 4 Smart Coil......................................................................................... 99

6 AK2-SC 255 Reference Manual RS.8D.M1.22
Board & points configuration, Seasons 4 Smart Coil ............................................................................ 99
ClimaTECHconfiguration ................................................................................................................ 100 - 109
Fan configuration, ClimaTECH................................................................................................... 100- 101
Coolingconfiguration, ClimaTECH............................................................................................ 101 - 102
Heating configuration, ClimaTECH ........................................................................................... 102 - 103
Dehumidificationconfiguration, ClimaTECH............................................................................. 103 - 104
Economizer configuration,ClimaTECH .............................................................................................. 104
Alarmconfiguration, ClimaTECH....................................................................................................... 105
Schedule configuration, ClimaTECH .................................................................................................. 105
I/O configuration, ClimaTECH ........................................................................................................... 105
Relay outputs (digital outputs), ClimaTECH ................................................................................. 106
Sensor inputs (analog inputs), ClimaTECH........................................................................ 106 - 107
On-offinputs (digital inputs), ClimaTECH........................................................................... 107 - 108
Addressand Initialization, ClimaTECH ........................................................................................ 108
Uploading ClimaTECH configuration to theAK2-SC 255 .................................................. 108 - 109
1.4 Lighting Configuration ................................................................................................110 - 114
Beginningconfiguration ..............................................................................................................................110
AK2-SC 255 lighting zone setup ........................................................................................................110-113
Board& points configuration, lighting ........................................................................................................113
Powerlinkconfiguration..............................................................................................................................113
Cutler-Hammerconfiguration ....................................................................................................................113
Powerlink and Cutler-Hammer board & point configuration .....................................................................113
Locate procedure ....................................................................................................................................114
1.5 Energy Meter Configuration (including demand limiting) .......................................114 - 121
Installation ....................................................................................................................................114
Configuration ...........................................................................................................................114 - 118
Wattnode Plus configuration ......................................................................................................................118
About soft starts ....................................................................................................................................119
Configuringdemandlimiting ............................................................................................................... 119-121
HVACdemand limiting .............................................................................................................. 119 - 120
Lightingdemandlimiting...................................................................................................................... 120
How demand limiting works....................................................................................................... 120 - 121
1.6 ConfiguringAlarms...................................................................................................... 121 - 140
The ConfigureAlarms menu ..................................................................................................................... 121
Configuring refrigeration alarms ...................................................................................................... 122 - 135
Alarms suspended ...................................................................................................................... 123 - 124
Suspending rack alarms ...................................................................................................................... 124
Configuringalarm settings.......................................................................................................... 124 - 126
Analog alarms .......................................................................................................................... 126 - 127
Field limits and units for analog alarms ......................................................................................... 127
Disablingalarms ................................................................................................................................... 127
What alarms are needed? ......................................................................................................................... 127
(Some) FrequentlyAsked Questions.................................................................................................. 127-128
Types of suction alarms, listed .................................................................................................................. 128
Compressor alarms .......................................................................................................................... 128 - 129
Circuit alarms .......................................................................................................................... 129 - 132
AK2-SC 255 circuits.................................................................................................................. 130 - 131
AKC 164 circuits ....................................................................................................................... 131 - 132

RS.8D.M1.22 AK2-SC 255 Reference Manual 7
1.6 Configuring Alarms (continued)........................................................................... 121 - 132
EKCK, DCU, and Degree Master circuits......................................................................................... 132
AKC 165 subcooling circuits............................................................................................................... 132
Condenser alarms ................................................................................................................................... 133
“Other” rack alarms............................................................................................................................ 134
Configuring Bitzer rack alarms ........................................................................................................ 134 - 135
HVAC alarm configuration .............................................................................................................. 135 - 138
AHU, RTU, and SC4 alarms .............................................................................................................. 136
RTC alarms ................................................................................................................................... 137
ClimaTECH alarms.................................................................................................................... 137 - 138
Miscellaneous alarms ....................................................................................................................... 138 - 140
Example miscellaneous alarm .................................................................................................... 139 - 140
Number of alarms field ....................................................................................................................... 140
1.7 Miscellaneous Points Configuration......................................................................... 140 - 154
Startingconfiguration ................................................................................................................................141
Plan strategy first ................................................................................................................................... 141
Miscellaneous relay outputs ............................................................................................................. 141 - 142
Miscellaneous sensor inputs ...................................................................................................................... 142
Miscellaneous on-off inputs....................................................................................................................... 142
Specifying miscellaneous conversiosn .............................................................................................. 142 - 143
Miscellaneouscalculations ............................................................................................................... 143 - 144
Point creation .......................................................................................................................... 144 - 145
Custom strategy example ................................................................................................................. 145 - 153
Creating the miscellaneous points -- Sensor inputs .................................................................... 145 - 146
Writing the custom strategy ................................................................................................................ 146
Datadefinitions .......................................................................................................................... 146 - 148
The rules area .......................................................................................................................... 148 - 149
Writingrules .......................................................................................................................... 149 - 150
Creating the miscellaneous points relay output ........................................................................... 151-154
Configuring Authorization........................................................................................................... 154
Configuring Units and Languages ............................................................................................. 155
PART TWO Using the Status Screens and Service Functions
Authorization -- “Just Looking”.............................................................................................................................. 157 -158
Geeting Authorized to make changes...................................................................................................................... 158- 159
Units and Languages -- Selecting .................................................................................................................................... 159
2.1 Navigation and Making Changes ............................................................................. 159 - 164
Getting back to the icon menu................................................................................................................... 162
Viewing and changing setting .................................................................................................................... 162
Changing numeric values .......................................................................................................................... 162
Changinglist fields .................................................................................................................................. 163
Changing the “From” and “To” times ....................................................................................................... 163
Changing the days of the week and holidays ............................................................................................ 164
Changinglabelfields ................................................................................................................................. 164

8 AK2-SC 255 Reference Manual RS.8D.M1.22
2.2 Using the Service Screens....................................................................................... 165 - 167
Auto/Manual Relays ....................................................................................................................... 165 - 166
<Reset> ................................................................................................................................... 166
Sensor adjustment ................................................................................................................................... 166
Maintenance hours .......................................................................................................................... 166 - 167
Bd/Pt locations ................................................................................................................................... 167
2.3 Using the Smart Case Controller Screens............................................................... 168 - 174
Introduction .......................................................................................................................... 168 - 171
Evaporator settings .......................................................................................................................... 171 - 172
Evaporator schedules ................................................................................................................................ 172
Evaporator service .......................................................................................................................... 172 - 174
Manual operation........................................................................................................................ 172 - 173
AKC 16x shutdown ............................................................................................................................ 173
Case cleaning .......................................................................................................................... 173 - 174
2.4 Using the Refrigeration Screens for Refrigeration Circuits.................................. 174 - 175
Evaporator Status screen ................................................................................................................. 174 - 175
Evaporator settings screen ........................................................................................................................ 175
Evaporator Schedules screen, Evaporator Alarms screen, and Evaporator Service screen..................... 175
2.5 Using the Communications Screens......................................................................... 176 - 187
Host Network screen ................................................................................................................................ 176
I/O Network Status screen .............................................................................................................. 176 - 177
List Points .......................................................................................................................... 177 - 179
List Nodes .......................................................................................................................... 179 - 180
IP Network (Ethernet) ..................................................................................................................... 180 - 181
Alarm routing for Ethernet ............................................................................................................... 181 - 182
Printer Settings screen ..................................................................................................................... 182 - 183
Modemconfiguration ....................................................................................................................... 183 - 186
Messages screen ................................................................................................................................... 186
2.6 Using the History Screens (for History Retrieval) .................................................. 187 - 192
Selecting points to view............................................................................................................................. 189
Displayinghistory .......................................................................................................................... 189 - 191
Graphinghistory .......................................................................................................................... 191 - 192
Stat (for statistics) ................................................................................................................................... 192
2.7 Using the Alarms Screens .......................................................................................... 193 - 197
The Alarms menu .......................................................................................................................... 193 - 194
The Active Alarms screen ............................................................................................................... 194 - 195
The Cleared Alarms screen ...................................................................................................................... 195
The Alarm Status screen.................................................................................................................. 195 - 196
The Network Alarms screen..................................................................................................................... 196
The Alarm Service screen ............................................................................................................... 196 - 197
2.8 Overrides ............................................................................................................ 198 - 200
Overrides using service screens ........................................................................................................ 198-199
Overriding sensor values ........................................................................................................................... 199
Overrides using RO8S switches .............................................................................................................. 199

RS.8D.M1.22 AK2-SC 255 Reference Manual 9
Overrides using the Manager’s Override box.................................................................................. 199 - 200
Keyswitch Override for refrigeration high temperature alarms................................................................ 200
2.9 Using the Audit Trail................................................................................................... 200 - 202

10 AK2-SC 255 Reference Manual RS.8D.M1.22

RS.8D.M1.22 AK2-SC 255 Reference Manual 11
PART ONE
Configuration
1 - 1. Initial Configuration
Note: We use the formal type designation “AK2-SC 255” occasionally in this manual, but
most often you will see the short form of the name: “SC 255.”
Configuration of anAK2-SC 255 is easy using the keypad and display, and even
easier using Danfoss AKA 65 Network Interface software running opn a PC con-
nected to the controller. This chapter describes configuration from the AK2-SC 255
keypad. You can easily adapt these instructions for the PC keyboard and mouse after
reading Chapter 3, “Using AKA 65 Software on Your PC.”
We will address configuration of each area of a supermarket control system in this
section of the manual. Initial configuration for equipment start-up may be limited to
such items as are necessary to check out the mechanical equipment or provide basic
service. The configuration can be changed or added to at any time later.
Battery The unit’s backup battery power is automatically enabled when the unit is first
externally powered. Note that if you receive the unit partially configured, the battery
will have been enabled. Normal battery life is a minimum of ten months, but the
battery is only used when main power is interrupted. In a unit which rarely experi-
ences power interruptions, the battery can last as long as eight years.
If the battery is disabled (by removing it, or when it ultimately discharges completely)
any information stored in the unit (set points, schedules, etc.) will be lost. Do not
remove the battery.
Authorizationcodes When the SC 255 is turned on for the first time, the Main Menu will appear as at left
below:
Before you can enter configuration information, you must select Authorization and

12 AK2-SC 255 Reference Manual RS.8D.M1.22
enter a valid authorization code and account code. Using the right arrow, move the
cursor to Authorization and press ENTER. TheAuthorization Menu will appear as
at right above, with the cursor in the Auth field.
When you have entered the access code and account number given to you by the
system owner, you will see the words Authorization accepted appear briefly in
reverse video at the very bottom of the screen. In the upper right, the screen will
show what the authorization level is.
After initial configuration, you will be able to make changes by several different
avenues, which are discussed in Chapter 5, “Using the System.”
Using menus To select from any SC 255 menu, first use the arrow keys to move the cursor to the
item you want, then press the ENTER key. You can use the EXIT key to retrace
your steps level by level.
Selection of Units
and Language Before using the system, you may wish to change the language used on the screens,
the units used for pressure and temperature, or the date and time format. These
settings will be for the local PC only, and will not affect the displays of any SC 255 in
the system. To change the displayed units, select Store Information from the main
menu and then choose Units/Languages. In the Configuration Units/Languages
screen, select the language you want to see in the controller screens, then select
either psi or bar for pressure; either °F or °C for temperature; and either % or fc
(footcandles) for light level.

RS.8D.M1.22 AK2-SC 255 Reference Manual 13
1 - 2. Configuring Refrigeration
There are two “routes” you may need to navigate to begin configuring refrigeration.
One begins by selecting Refrigeration from the Main menu, and the other by
selecting Configuration.
Starting with a
PartiallyConfigured
AK2-SC 255 If the AK2-SC 255 you are working with was supplied with a rack, the controller may
have been partially configured by the rack manufacturer. In that case, when you
select Refrigeration from the Main Menu, the SC 255 will display the Refrigeration
Menu (left). It lists the rack or racks that are partly configured. If you want to
change or add to the configuration of one of these racks, move the cursor to the rack
name and press ENTER. The Rack menu (right) will appear. In this example, only
one rack has been previously configured.
Select Configure Rack and the Configure Rack menu appears.
Now select the type of information you want to supply. We’ll cover a typical cat-

14 AK2-SC 255 Reference Manual RS.8D.M1.22
egory right after we talk briefly about the other “route” configuration may take.
Starting with a
Completely
Un-configured
AK2-SC 255 If theAK2-SC 255 you are working with has no refrigeration configuration at all,
select Refrigeration from the Main menu, and the Rack Configuration menu will
appear (left). The only selection which can be made from this screen is Add Rack.
Selecting Add Rack takes you to the Configure Rack, Rack Info screen (right).
Navigationand
making changes The Configure Rack A screen shown at right above has information fields that can be
changed by any user with a proper authorization code. To make changes, use the
arrow keys to move the cursor to the field you want to change
Enteringnumerals To enter numerals for a field like No of suction groups, use the numeral keys on the
controller keypad., then press ENTER.
Enteringlabels Labels are entries that you need to spell out. The Rack label field contains a label
one character in length. The Oil type field is also a label field, but it is 9 characters
long, allowing you to spell out a word or words indicating the oil type, for example,
“Mineral.”
To enter a label, place the cursor on the field, then press the +/- key. This action
toggles the function of the arrow keys so that the UP and DOWN arrows scroll
through the alphabet and all the other possible characters. Once the character you
want in that space appears, use the RIGHT arrow to move to the next space (when
the field has more than one space). Again, use the UP and DOWN arrows to reach
the character you want. When all the characters in the field are as you want them,
press ENTER to save the entry.
Constrainedfields The Rack label field is a constrained field. It will only accept an upper case letter,
even though lower case letters appear as you scroll through the characters. The No
of suction groups field is also constrained. It will only accept a single numeric
character from 0 to 5, because a single AK2-SC 255 can control up to 5 suction

RS.8D.M1.22 AK2-SC 255 Reference Manual 15
groups. Note that in the case of this particular field, entering a 0 (zero) will pop up a
warning box letting you know that a zero response here will eliminate the suction
groups already configured and will delete all information stored for the rack; you will
be asked to confirm the entry.
Selecting from list boxesThe next pair of illustrations shows how the controller uses list boxes.
The list box appears, as shown at left above, when you move the cursor to the field
and then press the +/- key (or, at your PC, right click). Then, using the UP and
DOWN arrow keys, you can move the cursor to make a selection. In the example at
right, R404A has been chosen. The cursor actually stayed in the same position, but
the “window” moved.
When you have put the list box’s cursor on the selection you want, press ENTER to
save your selection.
Some list boxes contain only two choices (for example, Yes and No in the Monitor
phase loss field). Some may contain many choices. When that is the case, one of the
lines in the box will contain three dots. When the cursor is moved to the three dots,
additional choices appear.
Now that we understand navigation and making changes, we can go on to a discus-
sion of each of the configuration screens.
Configuring Rack Info In the rack Info screens, the following are the fields, and their possible contents:
Rack label (Upper case letters, A to Z) The “name” of the rack.
2 stage system (List box:Yes, No)
No of suction groups (0 to 5) Note that for a rack with existing configura-
tion, entering and confirming a 0 will cause deletion of
allexisting rack information.
Refrig type (List box) The kind of refrigerant.
Oil type (9 characters, not constrained)
Monitor phase loss (List box: Yes, No) Whether or not there will be a

16 AK2-SC 255 Reference Manual RS.8D.M1.22
digital input from a phase loss monitor.
Generate input for each [appears only after a Yes answer to the preceding
question] (List box) Whether there is a phase loss
input for each rack or each suction group.
Shutdown phase loss [appears only after a Yes answer to the Monitor phase
loss question] (List box:Yes, No)
When all of the items on the Rack Info screen have been configured, press MENU to
return to the Main Menu.
Adding a Rack There is only one way to add a rack. From the Main Menu select Configuration,
then Refrigeration, and the Rack Configuration screen appears. At the bottom left of
the screen are the words >> Add Rack<<. Move the cursor there and press
ENTER. A new Rack Info screen will appear.
Notice that the Rack Label field contains the letter Bby default, since the previously
configured rack was rack A. You can change the default label if you want.
Configuring
SuctionInfo To configure a suction group, press MENU to return to the Main Menu, then select
Configuration, then Refrigeration. The Rack Configuration screen appears as at
left above. Select the rack and a Configure Rack menu appears (as at left below) .

RS.8D.M1.22 AK2-SC 255 Reference Manual 17
Once at suction configuration menu shown at right above, select the suction group you
want to configure and press ENTER. The Suction Info screen for that group will
appear as at right below. As you configure, questions may appear that are not
included on the default screen. The screen at left below shows all the possible lines
revealed.
The fields and their contents are as follows:
Suction I.D. (2 label fields: the first is a list box:Ato Z; the second
is 9 characters not constrained) This is the identifica-
tion you wish to assign to the suction group. The entry
will modify the screen title. For example, if you enter a
Bin the first field and Low Temp in the second, the
right portion of the screen title for the configuration
and status screens for this group will read Low Temp
AB.
PSIG target (-50.0 to 500.0) The pressure that the controller will
maintain, subject to capabilities of mechanical equip-

18 AK2-SC 255 Reference Manual RS.8D.M1.22
ment, for this suction group.
PSIG Safety cutout (-50.0 to 150.0) The gauge pressure at which the
controller will stop the compressors in this suction
group.
Adaptive suction control (List box)
None: No adaptive suction control.
AK2-SC 255: Target pressure is adjusted based on
discharge temperature of a single fixture.
AKC 16x: Adaptive control of individual evaporators
by an AKC 164 or AKC 161 Smart Case Controller.
Sensor: Target pressure is adjusted based on any
sensor on the AKC 55 I/O network
Dynamic: The SC 255 analyzes the performance of
every case on each individual circuit, and adjusts target
pressure intelligently by using the case sensor that
varies most from the setpoint.
Bd-Pt (For the first group, to the left of the hyphen, 01 to 99;
for the second group, to the right of the hyphen, 1 to 8).
The board and point address of the fixture sensor used
by the adaptive control algorithm. (Does not appear
when dynamic adaptive control is selected.) Note that
board and point numbers use a different format with
AK2 modules. See the AK2 I/O user manual for more
information.
Temp target (-50.0 to 100.0) The temperature that the adaptive
control algorithm will seek to maintain in the fixture.
(Does not appear when dynamic adaptive control is
selected.)
Range +/- (0.0 to 100.0) The dead band around the temperature
target. As long as the fixture temperature remains in
this range, the suction pressure target will not be
modified. (Does not appear when dynamic adaptive
control is selected.)
Maximum pressure float (0 to 99.9) The number of psig that the adaptive
algorithm will be allowed to cumulatively add or
subtract from the suction pressure target.
Post defrost delay (0 to 60) The number of minutes after termination of
defrost during which there will be no target adjustment.
(Does not appear when Sensor is selected as the type
of adaptive control.)
Allow float below target (List box: Yes, No) Determines whether or not the
adaptive algorithm will be allowed to adjust suction
pressure below the target if fixture temperature is
above target temperature + range.
Night setback (List box: Yes, No) Determines whether or not suction
pressure will be offset according to a schedule to be
specifiedin the following lines.
Setback from time (Time field) The start time for night setback.
Setback to time (Time field) The ending time for night setback.
Setback days (Days selection field) The days on which night setback
will be effective.

RS.8D.M1.22 AK2-SC 255 Reference Manual 19
Setback holidays (Holidays selection field) The holiday numbers on
which night setback will occur. Holiday numbers are
defined in Store Info configuration.
At the bottom right of the Suction Info screen are the words “PG DN” for more.
Use the controller’s PG DN key to reach the next screen; shown at left is the default
screen in which not all the questions and fields appear; the screen on the right shows
all the fields.
The fields and their contents are as follows:
Monitor suction temp (List box:Yes, No)
Display superheat temp (List box:Yes, No)
Monitor desuperheat temp (List box: Yes, No)
Close EEV valves during
rack shutdown (List box:Yes, No)
If suct above target by (0 to 999.9) Number of psig above target when AKV
valves will be closed during rack shutdown.
Delay time (0 to 45) Number of seconds after suction pressure
reaches target + the number specified in the preceding
field thatAKV valves will be closed.
Rack on AK2-SC 255 address
(0 to 15) The address of the SC 255 controlling the
rack that serves these EEVs.
Press EXIT to return to the Configure Rack Menu and continue refrigeration configu-
ration.
Configuring
two-stage systems and de-superheaters If (and only if) a rack is configured as a two-stage system, the
suction configuration for each suction group will include a special page for the low
side. The screen looks like this: