8
• See wiring diagrams supplied with the machine.
7.1 - DELIVERY STATE
• The control unit is supplied fitted in the
machine and factory pre-set.
• All the connections are made except those
concerning the available signals or the
options.
7.2 - PRINCIPLE
• The microprocessor controls the
operation of the machine and of the
associated alarms.
It continuously compares the water
temperature measured by the probe (Ai1)
and the setpoint temperature value
entered via the keyboard.
Each operating request generated by the
control system is signalled by indicator lights (6) or (8) - see below.
Each light flashes if a safety delay is in progress. The light shines steady when the corresponding circuit is in operation.
• The control probe is located on the water inlet in the factory.
7.3 - PRESENTATION
7.3.1 - DISPLAY KEYBOARD
(1) Key for:
- local On / Off control,
- access to parameters (in combination with button (2)),
- alarm clearance,
- hour counter reset.
(2) Key for:
- access to parameters (in combination with button (1)).
(3) LED display.
(4) Cooling mode indicator.
(5) Heating mode indicator (not used).
(6) Compressor on indicator, circuit A.
(7) Anti-freeze on indicator (not used).
(8) Compressor on indicator, circuit B.
(9) Decimal point: if illuminated when the operating time is displayed, the value must be multiplied by 100.
7.3.2 - CTN TYPE TEMPERATURE PROBE
• 10 k
Ω
at 25
°
C
7 - OPERATION OF "ECH" ELECTRONIC CONTROL
ECH 420 SRD
MICROPROCESSOR
CARD
Temperature
probe Ai2
(water outlet for
anti-freeze
protection)
Temperature
probe Ai1
(water inlet for
control)
DIGITAL INPUTS
ACTUATORS
12 VAC
SUPPLY
TRANSFORMER
Outside
temperature
probe Ai4
Temperature (
°
C)
-20
-10
0
10
20
25
30
40
50
60
70
Ohmic value (Ohm)
67,740
42,450
27,280
17,960
12,090
10,000
8,313
5,820
4,161
3,021
2,229
6
4
2
7
8
3
9
1
5
DISPLAY
KEYBOARD
