3 Commissioning
3.5 Power off/Interruption of the power supply
60 Modular PLCs XControl: XC-104-…, XC-204-…, XC-303-… 01/23 MN050005EN Eaton.com
3.5 Power off/Interruption of the power supply
When the program is running, the switching off or interruption of the (CPU)
power supply will cause the program cycle or all tasks to be aborted immedi-
ately. If this happens, data consistency will no longer be guaranteed!
All outputs in which the I/O tasks are used are set to 0 or switched off. The
behavior of retentive variables in shown in can be seen in Table9.
The remaining program cycle will not be completed when power is recon-
nected!
If data consistency is absolutely necessary for an application, additional mea-
sures are required, such as the use of a uninterruptible power supply with
battery back-up. The PLC is started as shown in Figure 47 and Figure 42.
Table 8 How the tags behave after the program starts
CPU operating state display
The CPU's operating state is indicated by the status display LEDs under PLC
and PRG in the front:
If the runtime system does not start properly, the PLC LEDs will signal the
NOT READY state. The CPU remains in STOP state. The CPU can be
restarted after elimination of the fault, see also ￫ Section “3.6 LED indica-
tors”, page 63.
3.5.1 Test and commissioning (Debugging)
The Modular PLCs XControl: XC-104-…, XC-204-…, XC-303-… supports the
following test and commissioning features:
• Breakpoint/Single step mode,
• Single cycle mode,
• Forcing,
• Online modification, ￫ PLC programming with CODESYS manual,
Chapter "Online functions",
Behavior of the variables after …
Variable type Cold start Warm start
Non-retentive Activation of the initial values Activation of the initial values
Retain Persistent Values remain in memory Values remain in memory
CPU status LED PLC
Green Red
RUN ON AUS
STOP
Flashes AUS
NOT READY AUS ON
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