Siemens S5-135U/155U - Manual (Page 276)

6-14
System Manual
C79000-G8576-C199-06
!
Warning
Since, in the test mode, no CPU can emit a BASP (output inhibit) in the
event of a fault, the test mode must be switched to the inactive state
without fail after completion of startup to avoid a critical or even
hazardous system state.
Before you can go into the test mode with the TEST switch, you have to
enable it on the module. This is achieved differently with the 923A and 923C
coordinators.
Insert jumper 3 - 14 on coding socket EP 45 as shown in the following
sketch.
14 16
8
9
1
3
EP 45
923A Coordinator
Set DIL switch S1.3 from Off to On (the following table shows the DIL
switches as delivered; see also Figure 6-2).
DIL S. on off Effect
S1.1
S1.2
S1.3
S1.4
S1.5
S1.6
x
x
x
x
x
x
–
–
Test mode
No. of occupied CPU slots = 2
No. of occupied CPU slots = 3
No. of occupied CPU slots = 4
When the coordinator mode switch is set from STOP to TEST, the CPUs can
be started individually. There is therefore no synchronized transition to
cyclic program processing. The output of signal BASP is suppressed on all
CPUs, even if there is an error.
f an error occurs with a CPU switched to RUN, only this one goes to the Stop
state in the test mode. The error is indicated by slow flashing of the CPU’s
STOP LED. The error at this CPU does not affect other CPUs.
If the test mode is not activated, a changeover from STOP to TEST does not
result in any reaction of the CPUs.
Test Mode
Enabling the Test
Mode with the
923A
Enabling the Test
Mode with the
923C
Reaction of the
CPUs
Multiprocessor Operation/Coordinators