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3 - HARDWARE DESCRIPTION
3.1 - General
Fig. 1 - Control board
9
10
7
Legend
1
CCN connector
2
Red LED, status of the board
3
Green LED, communication bus SIO
4
Orange LED, communication bus CCN
5
Remote master board customer control connection contacts
6
Remote slave board customer control connection contacts
7
Master board customer connection relay outputs
8
Slave board customer connection relay outputs
9
Master NRCP basic board
10 Slave NRCP basic board
The control system consists of an NRCP-BASE board for
single-circuit units and two NRCP-BASE boards (a master and
a slave board) for dual-circuit units. The units with the variable-
speed fan option, humidification or air quality sensor use the
slave board AUX1. All boards communicate via an internal SIO
bus. The NRCP-BASE boards continuously manage the informa-
tion received from the various pressure and temperature probes.
The NRCP-BASE master board incorporates the program that
controls the unit.
The user interface consists of two display blocks with up to 25
LEDs and 16 buttons (according to unit type). It is connected to
the main basic board and gives access to a full array of control
parameters.
3.2 - Electrical supply to boards
All boards are supplied from a common 24 V a.c. supply
referred to earth.
NOTE: When connecting the power supply for the boards,
preserve polarity, otherwise the boards may be damaged.
4
4
1
3
2
5
8
6
In the event of a power supply interrupt, the unit restarts auto-
matically without the need for an external command. However,
any faults active when the supply is interrupted are saved and
may in certain cases prevent a circuit or unit from restarting.
3.3 - Light emitting diodes on boards
All boards continuously check and indicate the proper
operation of their electronic circuits. A light emitting diode
(LED) lights on each board when it is operating properly.
•
The red LED flashing for a 2 second period on the NRCP-
BASE board indicates correct operation. A different rate
indicates a board or a software failure.
•
On dual-circuit units or units equipped with optional
board, the green LED flashes continuously on all boards to
show that the board is communicating correctly over its
internal bus. If the LED is not flashing, this indicates a SIO
bus wiring problem.
•
The orange LED flashes to show when all communication is
via the CCN bus.
3.4 - The sensors
Pressure sensors
Two types of electronic sensors (high and low pressure) are used
to measure the suction and discharge pressure in each circuit.
Thermistors
Room temperature sensors
Up to two sensors may be used. These sensors take into account
either an average room temperature or minimum and maximum
room temperatures, depending on the configuration.
•
Optional sensor T-56: this 10K sensor is fitted with:
-
an offset slider for adjusting temperature setpoint.
Moving the slider to the left (cold) allows temperature
setpoint to be reduced by as much as 3 K; moving it
to the right (warm) allows temperature setpoint to be
increased by up to 3 K (in steps of ± 1 K). When the
slider is in its central position there is no offset.
-
a button for extending the occupied period from one
to four hours depending on the occupied period
extension value entered in the configuration menu
(see section 4.3.11.3).
•
Optional sensor T-55: this 10K sensor is fitted with a
button for extending the occupied period.
Supply air sensor
The control system uses this to maintain a constant room
temperature. This is a Carrier 10K sensor.
Outdoor temperature sensor
This Carrier 5K sensor controls the economiser, allows the gas
heating stages to be used on the heat pumps and offsets the
room temperature setpoint where this is appropriate.
Water coil frost protection sensors
These Carrier 5K sensors are used on units fitted with hot
water systems.
Defrosting termination sensor
These Carrier 5K sensors are used by the defrosting function on
reversible units.
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