Yaskawa YASNAC PC NC PLC Programming Manual - Manual (Page 31)

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YASNAC PCNC PLC Programming Manual Chapter 5: Address Numbers And Map
(8) Address of Battery Back-up Memory (pm7000 to pm7099, #7100 to #9999)
For the memory to which addresses of #7000s are assigned, such memory is called the
“battery back-up memory”. The data saved to this type of memory are therefore retained
even when the power is turned OFF.
The battery back-up memory data are classified into the following three types:
• Sequence parameters:pm7000 to pm7099
• Keep relays: #7100 to #7999
• Keep memory: #8000 to #9999
(a) Sequencer Parameter Data
The sequencer parameter data are transferred from the NC main section to the PLC in the
following case in addition to the time when the power is turned ON.
Even if one item of sequencer parameter data is changed by parameter write operation, the
entire sequencer parameter data are transferred collectively.
In a sequence program, it is allowed only to read the sequence parameter data. Do not
attempt to change the data.
(b) Data in the Keep Relay and Keep Memory Data
Image data saved in the keep relays and the keep memory in the PLC change continuously
since the data are read and written as the sequence program is executed. Therefore, it is
necessary to transfer the latest image data in the PLC to the battery back-up memory in the
NC main section as the source data. This data transfer is called the automatic data trans-
fer.
While the power is ON, the data in #7100 to #9999 are collectively transferred from the
PLC to the NC.
In the PCNC PLC sequence ladder program, the battery back-up memory can be read
and written directly.
Fig. 5.1 Handling of PCNC Sequence Program