JUMO 705001 mTRON T - Central Processing Unit Operating Manual - Manual (Page 35)

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5 Operation
5.3 System switch
The central processing unit switch (Run/Stop/Reset) allows the various system states to be set.
However, the system state does not just depend on the switch position; it also depends on in-
ternal errors, which may prevent changeover to another state. For example, an error may result
in a system start being blocked, even though the switch is set to "Run".
Error states are indicated by the "Status" and "BusError" LEDs.
 Chapter 5.4 "LED displays", page 38
The setup program or a Web browser is used for diagnostics and, if necessary, also for trou-
bleshooting.
"Run" switch position
The system enters the "Run" state, provided there are no internal errors that prevent this.
 Chapter 5.2 "System states", page 34
During changeover from the "Stop" state to the "Run" state, an event message is issued (plant
"Run").
"Stop" switch position
The system enters the "Stop" state.
 Chapter 5.2 "System states", page 34
During changeover from the "Run" state to the "Stop" state, an event message is issued (plant
"Stop").
"Reset" switch position (button function)
This switch position triggers three different functions. Starting from the "Stop" position, the
switch must be pushed down in a specific sequence (button function) and held. If the relevant
sequence and the required times are not observed, the entire sequence must be repeated. Dur-
ing a sequence, LEDs signal the end of the time periods and successful completion of the se-
quence.
The following diagrams show the time sequence for the switch position (Reset, Stop) and the
signaling from the "Status" (S) and "BusError" (BE) LEDs. See also:
 Chapter 5.4.1 "Display modes", page 39
When the switch is pushed to the "Reset" position, both LEDs switch off. When the first thresh-
old in the sequence is reached (2 s), the "Status" (S) LED lights up in red. When the second
threshold is reached (10 s or 2 s if pushed again in "Origin" reset), the "BusError" (BE) LED
lights up in red. This allows you to see when the switch can be released.
If the sequence was completed successfully, the relevant reset is triggered. Both LEDs flash
for approx. 2.5 seconds as confirmation. If the sequence was incorrect, a reset is not triggered
and the LEDs resume the state that they were in before the start of the sequence.
NOTE!
In the "Stop" state it is not possible to set the PLC to the "Start" state using the CoDeSys
programming system.
NOTE!
The following reset sequences – except "origin" reset – can be performed only after basic ini-
tialization of the system.