Specifications

SLC 500™ Power Supplies
11
1746-IN004A-ML-P
Power Supply Undervoltage Operation
SLC 500 controllers continue to operate (hold-up) for a short period of time if the
input voltage to the power supply drops below the recommended operating
voltage range. The controller continues to scan the user program and control I/O
during this time. CPU hold-up for each power supply is shown on pages 9 and 10.
SLC 500 controllers turn OFF (stop scanning and disable outputs) if input
voltage to the power supply is removed or drops below the recommended
operating range for a period exceeding the CPU hold-up time. The controller
resumes operation automatically when the input voltage is restored to normal.
If the input voltage to the 1746-P7 power supply falls into a range of 4 to 9V for
a period exceeding the CPU hold-up time, the controller turns OFF and will not
turn back ON until:
• input voltage is increased to 11V dc.