Allen-Bradley micrologix 1500, Руководство пользователя

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Publication 1764-UM001A-US-P
6-4 Using Real-Time Clock and Memory Modules
Memory Module Write Protection
The memory module supports write-once, read-many behavior. Write protection is
enabled using your programming software.
Removal/Insertion Under Power
The memory module can be installed or removed at any time without risk of
damage to either the memory module or the controller. If a memory module is
installed while the MicroLogix 1500 is executing, the memory module will not be
recognized until either a power cycle occurs, or until the controller is placed in a
non-executing mode (program mode or fault condition).
Memory Module Information File
The controller has a Memory Module Information (MMI) File which provides
status from the attached memory module. At power-up or on detection of a
memory module being inserted, the catalog number, series, revision, and type
(memory module and/or real-time clock) are identified and written to the MMI
file. If a memory module and/or real-time clock is not attached, zeros are written to
the MMI file. Refer to the
MicroLogix 1200 and MicroLogix 1500 Instruction Set
Reference Manual , publication 1762-RM001B-US-P, for more information.
IMPORTANT
Once set, write protection cannot be removed. A change cannot
be made to the control program or data stored in a
write-protected memory module. If a change is required, you
must use a different memory module.