74 Rockwell Automation Publication 1756-UM001M-EN-P - February 2012
Chapter 3 Start Using the Controller
Clear the Program from On-board NVS Memory
If your application allows it, follow these steps to clear the program from the
1756-L7x controller’s on-board NVS memory.
1. Remove the ESM from the controller.
2. Remove power from the controller.
You can remove power in either of the following two ways:
• Turn power off to the chassis while the controller is installed in the
chassis.
• Remove the controller from a powered chassis.
3. Reinstall the ESM into the controller.
4. Restore power to the controller in one of these two ways:
• If the controller is already installed in the chassis, turn power back onto
the chassis.
• If the controller is not installed into the chassis, reinstall the controller
into the chassis and turn power back onto the chassis.
Estimate the ESM Support of
the WallClockTime
The ESM provides support for the maintenance of the WallClockTime of the
controller when power is not applied. Use this table to estimate the hold-up time
of the ESM based on the temperature of the controller and installed ESM.
Hold-up Time (in days)
Temperature 1756-ESMCAP 1756-ESMNRM 1756-ESMNSE
20
°C (68 °F) 12 12 0
40 °C (104 °F) 10 10 0
60 °C (140 °F) 7 7 0
Any action causing the 1756-L7x controller to reset (hard or soft), without an
ESM installed, will result in the controller’s wall clock time being reset to the
factory default of 01/01/1998.
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