Hardware Manual for the PCD2.M5 Series│Document 26/856; Version EN 12│2014-07-24
Saia-Burgess Controls AG
Data storage in case of power failure
PCD2.M5_ Classic CPUs and expansion housings
3-31
3
3.11
Data storage in case of power failure
The resources (registers, flags, timers, counters etc), and possibly the user program
and the text strings/DBs, are stored in RAM. To ensure that they are not lost and that
the hardware clock (where present) continues to run when there is a power failure,
the PCD2s are equipped with a buffer capacitor (SuperCap) or a buffer battery:
CPU type
Buffer
Buffer time
PCD2.M5_
Renata CR 2032 lithium battery
1...3 years
1)
1)
Depending on the ambient temperature; the higher the temperature, the shorter the buffer time
With new controllers, the batteries are packaged with the units, and have to be
inserted on commissioning. Observe the polarity of the batteries:
3.11.1 Battery changing
●
Remove PCD cover
●
Pull locking clip in the direction of the embossed plus sign on
the housing (see arrow)
●
Remove old battery
●
Insert new Renata CR2032 battery in such a way that the Plus
pole is in contact with the locking clip
CPUs with lithium batteries are not maintenance-free. The battery voltage is
monitored by the CPU. The BATT LED lights up and XOB 2 is called (if XOB 2 is not
programmed, the ERROR LED will also light up after 1 second of battery failure),
where
the battery voltage is less than 2.4 V
the battery is flat or shows an interrupt
the battery is missing
We recommend changing the batteries with the PCD attached to the power supply, to
avoid any loss of data.