Parker RAC Europe
PSD04 | User manual ver. 3.6 | Code 144PSDE364
page 59 of 74
9.7
Algorithm status
Bit 10 of Alarm status (AlSt) is raised for LOP, MOP, LoSH, HiSH, LowPressure or if the measures needed by the
algorithm are not valid.
This monitoring is in effect only while the system is working in SH-algorithm and in manual mode.
The Algorithm status (AlgS) variable holds the specific state that generated the alarm, according to this table:
Algorithm status
Description
Value 0
Value 1
bit 0
Measures acquired
Data not read (Alarm status.b10 0 1)
bit 1
algorithm is running
control algorithm halted
bit 2
algorithm is active
algorithm is skipped (manual mode is active)
bit 3
No LoSH algorithm is running
LoSH algorithm is running
bit 4
No LoSH alarm
LoSH alarm (Alarm status.b10 0 > 1)
bit 5
No HiSH algorithm is running
HiSH algorithm is running
bit 6
No HiSH alarm
HiSH alarm (Alarm status.b10 0 > 1)
bit 7
No LOP algorithm is running
LOP algorithm is running
bit 8
No LOP alarm
LOP alarm (Alarm status.b10 0 > 1)
bit 9
No MOP algorithm is running
MOP algorithm is running
bit 10
No MOP alarm
MOP alarm (Alarm status.b10 0 > 1)
bit 11
No LowPressure
LowPressure (warning signal only)
bit 12
No LowPressure alarm
LowPressure alarm (Alarm status.b10 0 > 1)
Note that if the manual mode is active, a read error of the measurement data due to incorrect probe configuration only
generates a warning. While, if the control algorithm is running, the inability to read the measurements makes it
impossible for the algorithm to continue, so this triggers a probe alarm.
Bits 0 and 1 of Algorithm status (AlgS) are always calculated, while the other bits, given their dependencies on the
active control algorithm, are only valid while SH-algorithm is running.
9.8
Algorithm protection functions
9.8.1
LoSH
When enabled (Pa10), this alarm is triggered when the SH drops below the low heating threshold (Pc02, Pp02, Pd02).
The condition is signalled in the Algorithm status (AlgS) and, when the timeout (Pa12) expires, an alarm is set.
The alarm and signal are cleared automatically when the SH returns above the threshold (hysteresis defined in Pa11).
9.8.2
HiSH
When enabled (PA20), this alarm is triggered when the SH rises above the high heating threshold (Pc03, Pp03, Pd03),
a bit is set in Algorithm status (AlgS) and, after the timeout (Pa22) expires, an alarm is set. The alarm and signal are
cleared automatically when the SH returns below the threshold (hysteresis defined in Pa21).
9.8.3
LOP
When enabled (Pa40), this alarm is triggered when the evaporation temperature (Te) drop below the LOP threshold
(Pc04, Pp04, Pd04). The condition is signalled in the Algorithm status (AlgS) and, when the timeout (Pa42) expires, an
alarm is set. This protection is most useful during start-up of the machine, when the evaporation temperature is
effectively low. It is possible to optimise this phase by setting a correct value in the valve opening on start-up
parameter (parameter Pc21 or Pp21). When the Te temperature returns within its limits (Pa41 defines the hysteresis),
the alarm and signalling are cleared and the normal regulation algorithm resumes.