EN/07.2013/58/102
Force single coil function
Address Description Note
24 SET FAN STATUS Get the evaporator fan status from the PLC to set the status without bypass the
delay times set by parameters(1 = ON; 0 = OFF). If the PLC asks to turn off the
evaporator fans and the compressor is on, the compressor is turned off first, then
the evaporator fans
25 SET DAMPER STATUS Get the damper status from the PLC to set the status (1 = ON; 0 = OFF)
26 SET HEATER STATUS Get the heater status from the PLC to set the status (1 = ON; 0 = OFF)
27 SET COMPRESSOR STATUS Get the compressor status from the PLC to set the status without bypass the delay
times set by parameters (1 = ON; 0 = OFF)
28 SET COMMUNICATION STATUS Get communication status from the PLC (1 = ERROR; 0 = NO ERROR)
124 RESET ALARMS Get the command from the PLC for reset the alarms (1 = RESET ALARMS; 0 = NO
OPERATION)
Write single register function
Address Description Note
8 SET COMPRESSOR VALUE Get the compressor value to send to Danfoss compressor (data point Modbus 40212
“Therm in compressor external speed PCT (AOC DRIVE)”) from the PLC. If data point
Modbus 27 SET COMPRESSOR STATUS - FORCE SINGLE COIL FUNCTION is
equal to 1(COMPRESSOR ON) then the minimum compressor value send to Danfoss
compressor is 1 %.
When custom 25 is enabled the machine is always on; by pressing the ON/OFF key is not possible to switch off the
machine. Also the stand-by mode is disabled.
When the evaporator fans are off, the compressor and the heater are always off. When the compressor is on (data point
Modbus 40301 greater than 0) it isn’t possible to switch off the evaporator fans.
The normal control is disabled and all devices, with the exception of the condenser fan, are controlled by PLC described
in the previous tables.
When the data point Modbus 28 is not updated by PLC to 0 for a time greater than M179 (off line status) and the alarms
fire - smoke and thermostat high temperature are not active, the freecooling damper is open completely; the heater, the
compressor and the condenser fan are switched off and the evaporator fans are switched on to the maximum speed.
Visualization
The parameter involved is:
• M179 DELAY FOR PLC COMMUNICATION ERROR ALARM: pre-set = 10 Sec
When custom 25 is enabled, in the fourth row of the first screen of the main menu it’s shown “on line”. When the data point
Modbus 28 is not updated by PLC to 0 for a time greater than M179, then in the fourth row it’s shown “off line”.
In the fourth screen (d) of the main menu it’s shown the compressor value set by PLC (data point Modbus 8).
Alarms
When custom 25 is enabled no alarm is associated to digital input A2.
• PLC communication error
The parameters involved are:
– I99 SELECT RELAY PLC COMMUNICATION ERROR ALARM: pre-set = CA
– M179 DELAY FOR PLC COMMUNICATION ERROR ALARM: pre-set = 10 Sec
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