The M218 controllers include an RTC to provide system date and time information and to support related functions requiring a real-time clock. To continue keeping time when power is off, a non-rechargeable battery is required (see reference below). A battery LED indicates if the battery is depleted or absent.
The table below shows how RTC drift is managed:
|
RTC characteristics |
Description |
|---|---|
|
RTC drift |
Less than 60 seconds per month without any user calibration at 25 °C (77 °F) |
The controller has one RTC battery (to be ordered separately).
In the event of a power interruption, the backup battery retains the time for the controller.
The table below shows the characteristics of the RTC battery:
|
Use |
In the event of a transient power outage, the battery powers the RTC. |
|
Backup Time |
At least 1.5 years at 45 °C max (113 °F). At higher temperatures, the time is reduced. |
|
Battery Monitoring Features |
Yes |
|
Replaceable |
Yes |
|
Controller RTC Battery Type |
Lithium thionyl chloride type, TSX PLP1 |
Installing and Replacing the RTC battery
While lithium batteries are preferred due to their slow discharge and long life, they can present hazards to personnel, equipment and the environment and must be handled properly.
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|
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EXPLOSION, FIRE, OR CHEMICAL BURNS |
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Follow all the instructions of the battery manufacturer. oFollow all the instructions of the battery manufacturer. oRemove all replaceable batteries before discarding unit. oRecycle or properly dispose of used batteries. oProtect battery from any potential short-circuit. oDo not recharge, disassemble, heat above 100 °C (212 °F), or incinerate. oUse your hands or insulated tools to remove or replace the battery. oMaintain proper polarity when inserting and connecting a new battery. |
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Failure to follow these instructions will result in death or serious injury. |
|
Step |
Action |
|---|---|
|
1 |
Power off your controller. |
|
2 |
Slide out the battery holder of the controller: 
|
|
3 |
Remove the battery from the battery holder. |
|
4 |
Insert the new battery into the battery holder in accordance with the polarity markings on the battery. |
|
5 |
Replace the battery holder on the controller and verify that the latch clicks into place. |
|
6 |
Power up your Modicon M218 Logic Controller. |
|
7 |
Set the internal clock. For further details on the internal clock, please refer to M218 RTC Library. |
