Chapter 2 Devices
2-89
SM408 (2 sec)
SM409 (2n sec)
SM410 (2n ms)
2n sec
2 sec
1 sec
n sec
2n ms
n ms
0.5 Hz
1/2n Hz
11. The flags related to the memory card
SM450~SM453, and SR453
The memory card is used to backup the data in the PLC. The corresponding functions of
these special auxiliary relays and the corresponding function of SR453 are as follows.
SM450
Whether the memory card exists
ON: The memory card exists.
OFF: The memory card does not exist.
SM451
Write protection switch on the memory card
ON: The memory card is write protected.
OFF: The memory card is not write protected.
SM452
The data in the memory card is being accessed.
ON: The data in the memory card is being accessed.
OFF: The data in the memory card is not accessed.
SM453
An error occurs during the operation of the memory card.
ON: An error occurs.
SR453
If an error occurs during the operation of the memory card, the error code
will be recorded.
12. The flags related to the I/○ module
SR655~SR730 record the mapping error occurring in the module table or the error occurring
in the I/○ module.
SR655~SR730 record the mapping error occurring in the module table.
If the mapping error occurs in the module table, the corresponding bit in the special data
register belonging to this module will be ON. Users can read the value in the special data
register to get the information about the position where the error occurs. For example, when
bit 5 in SR655 is ON, users can get the information that the error occurs at slot 5 in
backplane 1.
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