Just to confirm...
Battery: No
565038 - Does the MicroLogix 1000 have a replacement battery
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...&...
59845 - MicroLogix Processors that require a battery to retain user project and data
Access Level: Everyone
Memory: 1K EEPROM
27102 - MicroLogix 1000, 1100, 1200, 1400 and 1500 Memory Types and Sizes
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External Memory option of a sort: HHP
16122 - MicroLogix 1000 hand-held Programmer ( HHP ) using a Memory Module
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...&...
25201 - How to use the 1761-HPP-B30 with the MicroLogix memory and the HHP memory module
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Load from Memory Module: No (only HHM in HHP)
67588 - Is there a memory module for the MicroLogix 1000?
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Data File Protection: No
9550 - File Protection Options for SLC and MicroLogix Controllers
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To answer the opening question...
diat150 said:
How does the backup situation work with the Micrologix 1000? If setpoints are changed in the PLC will it hold those if you power it down?...
Yes - When powering OFF the current Data File values will be saved to EEPROM and then restored at power up.
diat150 said:
...or will it default back to whatever is set in the program that was downloaded to the PLC?...
No - When a program is downloaded to the controller the offline Data File values are also downloaded, but they are not stored in any special memory or way so that the values could be referenced for a future "default" operation to restore the Data File values back to an "as downloaded" state.
After downloading the program - as soon as the Data File values are manipulated, manually or by the running program, the original values are now overwritten. At any point in time that the controller is power cycled, the values will now be saved to the EEPROM at whatever value they happen to hold at the time. An address value may happen to be the same as when it was downloaded, or not. If the value happens to be the same then it is just coincidence or perhaps it had never changed since the last download was performed - all application dependent, of course.
diat150 said:
...Assuming that no type of logic is written to write setpoints back to default using the first scan bit.
You would have to use a method such as this if you do want to automatically default the controller Data File values back to a known Data Set at each power up or "Go to Run". Usually this involves designating addresses within the controller to store the default values to be copied to the working address registers. The default values must never be destructively operated upon - i.e. written to, unless changing a default setting manually.
Other than using a method to achieve similar to this, you would have to perform another download of the program that contains the Data Set you wish to load.
Regards,
George