1-6
µµ
P-D Microprocessor
Specifications
CSR-20 & CSR-40, September 1999
Thermoguard
®
µµ
P-D Microprocessor
Temperature Controller:
Type
Thermoguard
®
µ
P-D microprocessor with digital thermostat, ther-
mometer and fault indicator monitor
Setpoint Range
-30.0 to +30.0 C (-22.0 to +86.0 F)
Digital Temperature Display
-40.0 to +130.0 C (-40.0 to +266.0 F)
Output Module
Energizes and de-energizes unit contactors and solenoids in
response to serial communications commands from the
µ
P-D con-
troller. Indicator LEDs on the Output Module indicate an output is
energized. RXD and TXD indicator LEDs alternately flash to show
the communications connection is good. If one or both of the RXD
and TXD LEDs do NOT flash, the communications connection is
open or defective.
Thermo Bus PC Board
Transfers the serial communications commands from the
µ
P-D con-
troller to the Output Module.
Power Module PC Board
Supplies low voltage control power to the
µ
P-D controller, Output
Module and modulation valve. Fuses provide current overload pro-
tection to unit control circuits.
Controller Software (Original Equipment):
Version
See controller identification decal
Unit Configuration (CFG U)
See controller identification decal
Customer Configuration (CFG C)
See controller identification decal
Defrost Initiation
Evaporator Coil Sensor
Coil must be below 10 C (50 F) to initiate defrost by demand, timer
or manual switch
Demand Defrost
Demand defrost function initiates defrost when the return air and
refrigeration systems conditions indicate the presence of frost or ice
Defrost Timer: Chill Mode*
• Default: Every 3 hours until two timed defrosts occur without a
demand defrost in between. Then defrost interval increases 1 hour
every other timed defrost interval. Maximum time interval is 8
hours
• Customer Configuration C5: Standard default times but maximum
time interval is 6 hours on chill loads.
• Customer Configuration C6: 2 hour initial defrost, then maximum
time interval is 6 hours on chill loads.
Defrost Timer: Frozen Mode*
• Default: Every 6 hours until two timed defrosts occur without a
demand defrost in between. Then defrost interval increases 2
hours each timed defrost interval. Maximum time interval is 24
hours
• Customer Configuration C5: Standard default times but maximum
time interval is 12 hours on frozen loads.
• Customer Configuration C6: 2 hour initial defrost, then maximum
time interval is 6 hours on frozen loads.
*Timed defrost intervals reset to initial value after a manual defrost, after the unit has been OFF for 48 hours and after a setpoint
change from Chill to Frozen mode or Frozen to Chill mode.
