PM 740 T
page 8 of 21 File: PM740T_r3eng - Settembre 2004 - Manuale per: PM 740 T
PM 740 PM 740
PM 740 T
File: PM740T_r3eng - Settembre 2004 - Manuale per: PM 740 T page 9 of 21
Working modes
The working capability of the PM740 depends upon its
“working mode”: it has several modes each with a different
meaning and functionality.
These modes are:
POWER-ON: it goes in this mode at power-on, when the main
breaker is set to 1: the CPU performs some internal controls,
display the factory’s logotype and after few seconds, the unit
enters the Stand-By mode.
STAND-BY: This is a waiting state, the unit is powered but not
yet ready to generate microwave as the magnetron lament is
not powered. In this mode all of the working parameters can
be set from Operator Panel; the unit enters in Stand-By from
the previous Power-On state or from a Reset state. The unit
exits from Stand-by and goes to Preheating only if there are no
alarms present, and the “hibernate” command is OFF.
PREHEATING: This is a temporary state, controlled by an internal
timer, whitch allows the lament to be heated. Entrance in this
mode is done by an external command or automatically after
the end of the Power-On state. When the timer has elapsed the
unit goes into the Ready mode.
READY: The unit waits for the external enable command to
generate power to the magnetron. The magnetron lament has
been heated.
The unit may remain in this state as long as needed: it auto-
matically exits should any alarm be generated or when the
”hibernate” command is set. When the ENABLE command is
set the unit enters into the “MW-ON” state.
MW-ON: When this appears on the LCD screen the unit is gene-
rating microwave emission at the preset power level.
The unit exits from this mode if:
* the enabling command is set OFF. It will now enter
the Ready state.
* any ALARM signal is generated. It goes into the
Alarm state.
* Hibernate signal is set ON.
ALARM: In this state the output power and the lament is
immediately shut-off.
The alarm type is indicated on the display.
The unit will exit the Alarm mode and enter the Reset Wai-
ting state only when the alarm cause is removed, the enable is
disactivated and the “RESET” signal (CONN#5) is activated.
RESET WAITING: The unit enters in this state when the alarm
cause is cancelled and the enable command is still present
(ON). The unit exits from this condition and enter in Reset
mode, only when the enable command is switched OFF.
RESET: This is a temporary state, driven by a two seconds
timer. When the timer is elapsed the Reset state ends and the
PM740 automatically enters the Stand-By status.
Description of the external commands.
HIBERNATE: has value ON/OFF.
- If ON the magnetron’s lament is not powered and the
PM740 goes into the Stand-by state.
- If OFF the lament is heated and when the related timer
has elapsed, the unit enters the Ready mode. The
heating timer value can be preset from the front panel.
- If a user does not wish to use the Hibernate function, it
may remain disconnected and the system will treat it as in
OFF condition.
POWER ENABLE: has value ON/OFF.
This signal will depend on the state of the HIBERNATE signal:
a) ENABLE OFF and HIBERNATE OFF
the unit performs lament preheating and goes in
Ready state but does not generate output power;
b) ENABLE OFF and HIBERNATE ON
the unit is in the Stand-by state but does not generate
output power;
c) ENABLE ON and HIBERNATE OFF
the unit awaits the end of preheating sequence and
then starts to generate output power provided that the
power set signal is > 10%.
d) ENABLE ON and HIBERNATE ON
the unit is the Stand-by state but does not generate
output power.
POWER SET: This is an analog input signal and set the level
of out power.
When its value is lower than 9% of full value the unit does not
generate any output power, when its value is greater than 9% of
full value the unit generates power proportional to signal value:
the signal is 0-10V.
