Carel MPXPRO User Manual page 31

MPXPRO, inside the showcase or cold room, can use temperature probes
to measure:
• the air outlet temperature (evaporator outlet);
• the defrost temperature (in contact with the evaporator);
• the air intake temperature (evaporator inlet).
The default confi guration for the assignment of the control probes is as
follows:
• S1 = Outlet probe (Sm);
• S2 = Defrost probe (Sd);
• S3 = Intake probe (Sr).
The default confi guration also involves these three probes being standard
CAREL NTC. However, other types of probes can be connected by setting
parameter /P1, if the product code allows that.
On MPXPRO the default settings can be changed to choose the function
associated with any of the probes connected.
There are also cases where the characteristics of the applications require
diff erent settings.
Examples:
Control inside a cold room is normally performed using just two
temperature probes, in particular the intake temperature is not read. In
this case, the possible confi guration may be:
• /FA=1: outlet temperature on probe S1 (Sm=S1);
• /Fb=2: defrost temperature on probe S2 (Sd=S2);
• /Fc=0: no intake temperature;
Alternatively:
• /FA=1: outlet temperature on probe S1 (Sm=S1);
• /Fb=3: defrost temperature on probe S3 (Sd=S3);
• /Fc=0: no intake temperature.
Share control status
This function is used to satisfy the needs of cold rooms or showcases with
multiple evaporators, where the Slaves are essentially used as expansions
for the management of diff erent electronic valves. This function shares
the Master control status across the tLAN network. In this way, the Master
determines the control status, and each Slave operates as a consequence,
without consider the parameters set locally. This means Slave controllers
can be used without outlet and intake probes. If the Slave controller is
not accessible from the Master, "duty setting" operating mode must be
activated, setting the corresponding parameter c4 >0.
Activation: to activate sharing of the control status, set /FA = 0 and /Fc =
0 on the controllers MPXPRO Slave.
Note:
• the confi guration /FA = 0 and /Fc = 0 on a Master controller causes
the alarm 'rE';
• if the Slave controller is not accessible from the Master, alarm 'MA' is
displayed.
The function manages the control status (activation and deactivation
of the cooling request) on the Slave controllers from the Master via the
tLAN network. This means that only the Master parameters (set point,
diff erential, night-time set point variation, control off set in the event
of probe error) aff ect the control algorithm. The value of the Slave
parameters has absolutely no infl uence. If the Slave controller is not
accessible from the Master (the user interface shows alarm 'MA'), "duty
setting" mode is activated based on the local setting of parameter c4, and
the corresponding management (duty setting starts in the status found
prior to the instant it is activated, i.e. it starts with compressor on if this
was on, and with compressor off if it was off ).
Note: activation of the continuous cycle on the Master means all
the dependent Slave observe the compressor management times
of the Master controller (only parameter cc on the Master has an eff ect,
while the values set on the Slaves are ignored). This operating mode is
only highlighted on the Master user terminal, as the Slave controllers
ignore the Master control mode. This means that a Slave controller
serving the Master, even in the continuous cycle, manages the user
interface as if it were in normal control (compressor icon on during
cooling request and off when no request). Attempts to activate
continuous cycle on a Slave serving the Master are ignored, both local
and sent from the Master.
Note: if the Master controller enters duty setting mode, the related
Slave controllers follow as regards the compressor management
times and the user interface does not show the icon fl ashing when the
compressor is off , due to the fact that they ignore the Master control
mode. On the other hand, if the Slaves enter duty setting mode due to
lack of communication with the Master; in this case they manage the user
interface correctly.
Calibration (parameters /c1, /c2, /c3)
MPXPRO can adjust the values read by the probes and some of the
internal variables. In particular, /c1 to /c3 are used to increase or decrease
the values read by the physical probes connected to the inputs S1, S2, S3,
if confi gured as temperature probes. Parameter /cE, on the other hand,
corrects the value of the saturated evaporation temperature calculated
directly based on the evaporation pressure. The serial probes cannot be
calibrated, while the probes shared with the Master are calibrated by the
Master.
T2
A
min
Key
T1 Temperature read by the probe
T2 Value calibrated by T1
A Off set
min, max Range of measurement
Par. Description
/c1 Probe 1 calibration
/c2 Probe 2 calibration
/c3 Probe 3 calibration
31
ENG
T1
max
Fig. 5.b
Def Min Max U.0.M.
0 -20 -20 (°C/°F)
0 -20 -20 (°C/°F)
0 -20 -20 (°C/°F)
Tab. 5.e
MPXPRO - + 0300055EN rel. 1.1 30/08/10