Power-Up And Power-Down Sequences; Power-Up Sequence; Power-Down Sequence - GE PACSystems RXi User Manual

Chapter 5. CPU Operation

Power-Up and Power-Down Sequences

5.11
Note:

5.11.1 Power-Up Sequence

System power-up consists of the following parts:
■
■
■
■
Power-Up Self-Test
On system power-up, the CPU module executes hardware checks and software validity
checks.
If a low or failed Energy Pack fault indication is present, a fault is logged in the Controller
fault table.
CPU Memory Validation
The next phase of system power-up is the validation of the CPU memory. First, the system
verifies that user memory areas are still valid. A known area of user memory is checked to
determine if data was preserved. Next, if a ladder diagram program exists, a checksum is
calculated across the _MAIN ladder block. If no ladder diagram program exists, a checksum
is calculated across the smallest standalone C program.
When the system is sure that the user memory is preserved, a known area of the bit cache
area is checked to determine if the bit cache data was preserved. If this test passes, the Bit
Cache memory is left containing its power-up values. (Non-retentive outputs are cleared on a
transition from Stop to Run mode.) If the checksum is not valid or the retentive test on the
user memory fails, the bit cache memory is assumed to be in error and all areas are cleared.
The CPU is now in a cleared state, the same as if a new CPU module were installed. All logic
and configuration files must be stored from the programmer to the CPU.
System Configuration
After completing its self-test, the CPU performs the system configuration. It first clears all
system diagnostic bits in the bit cache memory. This prevents faults that were present before
power-down but are no longer present from accidentally remaining as faulted.
I/O System Initialization
The operation of input and output defaults for remote I/O modules in an RXi PROFINET
network is described in Section 10.7.5, I/O Defaults Operation.

5.11.2 Power-Down Sequence

System power-down occurs when the CPU detects that incoming DC power has dropped
below 18Vdc for more than 15ms.
If an operational Energy Pack is connected, it maintains power long enough for the Controller
to write its user memory contents to non-volatile memory.
94
To ensure user memory backup, an operational Energy Pack must be attached at the
moment of power-down and at power recovery.
Power-up self-test
CPU memory validation
System configuration
I/O system initialization
PACSystems* RXi Distributed IO Controller User Manual GFK-2816F