A52x Series Electronic Refrigeration Controller with Adaptive Defrost Technical Bulletin
4
Figure 3: A52x Controller Low Voltage Terminal Block Connections
Table 2: A52x Controller Low Voltage Terminal Blocks, Terminals, and Wire Sizes
Terminal
Block Label
Terminal
Label
Description, Function, and Requirements
Recommended
Wire Sizes
RS485
MODBUS
A +
The RS485 Modbus communications terminal block is restricted to the
optional PENN Precision Superheat Controller (PSHC). Do not connect
any other Modbus device to these terminals.
0.20 to 0.30 mm
2
(26 to 22 AWG)
Stranded wires
and twisted-leads
cable
B -
REF
RS485 Modbus signal common or reference.
ANALOG
INPUT/
OUTPUT
Sn1
The main space temperature sensor. Connect either lead from the
sensor to Sensor 1 (Sn1). Connect the other lead to a common (C)
terminal.
Note:
Sensor wires for the A52x Controller are not polarity sensitive.
0.30 to 1.50 mm
2
(22 to 16 AWG)
Stranded wires
and twisted-leads
cable
C
There are four low-voltage common terminals. All of the low-voltage C
terminals are connected together on the PC board.
Sn2
The evaporator temperature sensor. Connect either lead from the sensor
to Sensor 2 (Sn2). Connect the other lead to a C terminal.
Note:
Sensor wires for A52x Controller are not polarity sensitive.
Sn3
Not available
UI4
Universal Input 4 can be configured as a 0–10 VDC analog input or dry
contact binary input. Connect a 0 to 10 VDC input or binary input to the
UI4 (+) terminal and a C (common/-) on the low voltage terminal block.
UI5
Universal Input 5 can be configured as a 0–10 VDC analog input or dry
contact binary input. Connect a 0 to 10 VDC input or binary input to the
UI5 (+) terminal and a C (common/-) on the low voltage terminal block.
AOI
Note:
Analog Output 1 (AO1) is not supported in the A525. Make no
connection to this terminal. The A524 Controller does not include
an analog output and does not have an AO1 terminal block.
