Ti545/Ti555 Memory And Mode Status At Power-Up; Table 5-3 Ti545/Ti555 Mode And Memory Status After Power-Up - Siemens SIMATIC TI555 System Manual

5.2

TI545/TI555 Memory and Mode Status at Power-up

TI545/TI555 System Manual
When you power up a TI545/TI555 system, the CPU checks the status of the
EEPROM (EPROM) and the battery. A clear (un-programmed) EEPROM
(EPROM) is equivalent to having no EEPROM (EPROM) installed.
Table 5-3 lists mode and memory status (after power up) that result from
various battery and EEPROM (EPROM) conditions.

Table 5-3 TI545/TI555 Mode and Memory Status After Power-up

Conditions
Programmed
Battery
EEPROM (or EPROM)
Status
Installed and Selected
Bad or Off No
Bad or Off Yes
Good and
No
On
Good and
Yes (same program)
On
Good and
Yes (different program)
On
Results
Controller Memory
Cleared
Cleared, then loaded with
program that is in
EEPROM (EPROM)
No change
No change
Cleared, then loaded with
program that is in
EEPROM (EPROM)
Using an EEPROM or EPROM
Controller
Mode
PROGRM
RUN
Mode prior
to power
loss
Mode prior
to power
loss
RUN
5-5