Omron CPM1A operation manual Memory Backup, Backup method Data

Specifications			Section 2-1
	Note 1. Use TIM 000 to TIM 003 when creating a timer using the high-speed timer
		instruction to perform interrupt processing.
		2. The input interrupt response time is 0.3 ms max.
Memory Backup		The user program and memory area data in the CPM1A are backed up either by
		an internal capacitor or in flash memory as shown in the following table.
		Backup method	Data
		Internal capacitor	Read/write DM area (DM 0000 to DM 0999, DM 1022, and
			DM 1023)
			Error log area (DM 1000 to DM 1021)
			HR area (HR 00 to HR 19)
			Counter area (CNT 000 to CNT 127)
		Flash memory	User program
			Read-only DM area (DM 6144 to DM 6599)
			PC Setup (DM 6600 to DM 6655)

Note 1. The IR, TR, LR, and timer areas are not normally backed up when power is turned off and all contents will be cleared the next time power is turned on. (The PC Setup setting in DM 6601 can be used to back up this data. Refer to details on the PC Setup later in this manual for details.)

2.The bits in the AR and SR areas have special functions and are set accord- ing to these functions when power is turned on.

The capacitor backup time depends on the ambient temperature, as shown in the following graph. The backup time, however, assumes that the capacitor is fully charged, which requires that power be supplied to the CPU Unit continu- ously for at least 15 minutes.

Backup time (days)

20

10

7

1
25	40	80

Ambient temperature (_C)

If the power remains off for a period exceeding the data backup period, AR 1314 will turn ON to indicate that the capacitor can no longer back up data and the data backed up by the capacitor will be cleared. AR 1314 will remain ON unless it is turned OFF using I/O monitor operations, using memory clear operations, or from the user program.

If desired, the PC Setup setting in DM 6604 can be set to create a fatal error and thus stop the system when AR 1314 goes ON.

The data stored in flash memory will not be lost even if power remains off for a period exceeding the data backup period, because the data stored in flash memory will be read to the CPU Unit when the CPM1A is turned on.

If the power is turned off without changing the mode from PROGRAM mode to RUN or MONITOR mode after having made changes in the data that is backed up in flash memory, the changes will not be written to flash memory. If the power is then left off for more than 20 days (at 25_C), the changes (i.e., the contents of the RAM) will be erased and the data values will become undefined.

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