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Operating and Maintenance Instructions – 7 Hardware and software
Rittal Liquid Cooling Package Plus
The fans have four speeds. Four relays control two fans. Both fans that belong
to a control unit run with the same speed and are connected to the control unit
(RLCP fan) via a 5-pole cable using a connector. The fans are equipped with
an echo sensor, which reports the speed signal to the control unit (sockets X6
and X7).
X6/X7 pin assignment:
1
+ 5 V DC
2
Gnd
3
Echo sensor
Furthermore, the control unit has two sockets (X8 and X9) for connecting tem-
perature sensors. One of these sensors is inside the fan module and one is on
the front of the heat exchanger. The air temperature in front of the fans (that is,
the temperature of the air drawn in from the server enclosure, X9) and the tem-
perature behind the heat exchanger (that is, the temperature of the cold air sup-
plied to the server enclosure, X8) are measured.
X8/X9 pin assignment:
1
NTC (5 V/max. 0.5 mA)
2
Gnd
X3 pin assignment (power supply):
1
L
2
N
X4/X5 pin assignment (power supply of the fan modules):
1
L (Speed 1)
2
L (Speed 2)
3
L (Speed 3)
4
L (Speed 4)
5
N
7.2.2 Status LED
The control unit includes an LED which displays the internal status.
The control unit's software continuously reads the analogue values from the
temperature sensors via the analogue channel and establishes an average va-
lue for each sensor. Next, it reads the temperature value in °C from a table and
writes this in the I
2
C transmission buffer.
Furthermore, the software counts the speed pulses of both connected fans and
also writes this into the I
2
C transmission buffer.
The fan set speed determined by the control unit is evaluated and the approp-
riate fan speed is set on the fans via relays. An LED on the fan module shows
an error code, which is indicated by short flash pulses.
0
No error (LED constantly on). The I
2
C data traffic is indicated as the LED is
briefly extinguished when a data packet is requested.
1 Temperature
sensor
defect
2 Fan speed error fan 1
3
Fan speed error fan 2
4 I
2
C timeout (approx. 20 s)