Led Error Signalling; Program Errors; Determining An Error Address - Siemens SIMATIC S5 Manual
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S5-115F Manual
5.1.3
LED Error Signalling
Certain errors are indicated by LEDs on the CPU. Table 5-3 explains these error signals.
LED
QVZ
Time out
lights up
(The CPU has entered the "STOP" mode.)
ZYK
Scan time exceeded
lights up
(The CPU has entered the "STOP" mode.)
BASP
Digital outputs are disabled.
(The CPU is in the "RESTART" or the "STOP" mode.)
5.2
Program Errors
5.2.1
Determining an Error Address
The STEP address counter (SAZ) in the ISTACK (bytes 25 and 26) indicates the absolute memory
address of the STEP 5 statement in the PLC before which the CPU has entered the "STOP" mode.
You can use the "DIR PLC" programmer function to determine the appropriate block starting
address.
Example:
Figure 5-3 shows a program consisting of OB 1, PB 0, and PB 7. PB 7 contains an illegal statement.
OB 1
JU PB 0
BE
Figure 5-3. Structured Program with Illegal Statement
EWA 4NEB 811 6149-02
Table 5-3. Meaning of the Error LEDs on the CPUs
PB 0
JU PB 7
BE
Meaning
PB 7
Illegal
statement
BE
Error Diagnostics
5-5
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