Siemens SIMATIC S5-90U System Manual page 115

S5-90U/S5-95U
Example: Program scanning was interrupted at function block FB2. The programmable controller
went into the "STOP" mode with the error message "TRAF" (because of incorrect DB
access, e.g., DB5 is two words long, DB3 is ten words long).
"BSTACK" lets you determine the path used to reach FB2 and which DB was open at
the time of call up. "BSTACK" contains the three (marked) block start addresses.
OB1
00 JU PB1
02
04 JU PB2
06
08 JC PB3
10
xx BE
BLOCK STACK
Block No. Block Add.
PB 4 0174
PB 2 011A
OB 1 0152
The above BSTACK display indicates a block was called up via the path of OB1 PB2 PB4.
During processing of this block, the programmable controller went into the "STOP" mode.
DB5 was valid when this block was called.
Refer to the ISTACK for the block that was being processed when the error occurred and for the
cause of the error.
EWA 4NEB 812 6115-02b
PB1
00
xx BE
PB2
00 C DB5
02 JU PB4
04
xx BE
PB3
00 C DB3
16 JU FB2
18 BE
Figure 5-4. Program Tracing with "BSTACK"
Table 5-8. BSTACK Display
Return Add.
0174
011A
0152
Diagnostics and Trouble Shooting
PB4
00
08 JC FB2
10
xx BE
Rel. Add. DB No.
0000 DB 5
0000 DB 5
0000
Interrupt with the
"TRAF" error
message
FB2
00
2A L DW4
xx BE
DB Add.
0164
0164
5-11