Rockwell Automation 1747-PT1, D1747NP002 Hand-Held Terminal - Manual (Page 230)

Chapter 16
Bit Instructions
16–6
When the processor changes from the Run to the Program mode or when
power is lost (provided there is battery backup or the capacitor retains
memory), the last true output latch or output unlatch instruction in the ladder
program continues to control the bit in memory. The latched output device is
energized even though the rung conditions controlling the output latch
instruction may have gone false.
!
ATTENTION: Physical outputs are turned off under processor
fault conditions. However, when error conditions are fixed, the
controller will resume operation using the data table value stored
at the instruction address.
Your program can examine a bit controlled by OTL and OTU instructions as
often as necessary.