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System Startup
4.1.3
CPU Operation in "RUN" and "STOP" Modes
In these modes the CPU can operate in two ways:
•
Safety mode
The CPU is automatically in safety mode as soon as an EPROM submodule is plugged in.
•
Test mode
In all other cases, the CPU is automatically in test mode.
Safety mode and test mode differ from each other in the following points:
•
Programmer operation ( Volume 2, Chapter 4 of the manual):
In safety mode and in "RUN" mode at present, the operator cannot use the programmer input
functions; in "STOP" mode, he is restricted mainly to enquiry functions only, but cannot make
entries that will change the contents of the RAM (exception: inputs using the parameter entry
DB). In test mode and in "RUN" mode, the programmer can be used for enquiry and test
functions and, in "STOP"mode, the whole range of programmer functions is available.
•
Supplementary self-test with test slice organization ( Volume 2, Section 5.4.1 of the manual)
In test mode, the RAMs of the two subunits are not compared and no restart test takes place.
•
Transmission of the RAM contents of subunit A to subunit B (on restart, to transfer any pro-
gram changes to subunit B):
In safety mode, the parameter entry DB can only be changed when the PC is in "STOP" mode;
for this reason, it is transferred to subunit B on restart. In test mode, the entire user RAM
(5 Kbytes of internal RAM plus the contents of any RAM submodules) is transferred to
subunit B to cope with any blocks loaded later.
•
Error response:
In safety mode, there are the following error responses:
- "Passivate" (deactivation of I/O modules)
- "Large STOP loop" and
- "Lesser STOP loop".
•
Passivation entries
Passivated I/O modules can be re-activated during operation using the FB 255.
The passivation entries in the error DB are deleted.
Passivation is also revoked in the following cases:
- In safety mode with Overall Reset
- In test mode by performing the following: Power OFF, Power ON, RUN.
•
Deleting entries for RAM comparison errors
In safety mode, entries for RAM comparison errors can only be removed with an Overall Reset.
Other error entries are deleted on restart.
4-6
S5-115F Manual
EWA 4NEB 811 6148-02
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