Hardware Manual

Hardware Manual PCD 1 / PCD 2 Series│Document 26 / 737│Edition EN 15│2008-07-22

Saia-Burgess Controls AG

Data storage in case of power outage

CPUs and expansion housings

3

3.14 Data storage in case of power outage

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 outage,

the PCD1/PCD2 are equipped with a buffer capacitor (SuperCap) or a buffer battery.

CPU type Buffer Buffer time

PCD1.M110 Super Cap (soldered) 30 days1)

PCD1.M120/M125 Super Cap (soldered) 7 days

PCD1.M130/M135 CR 2032 lithium battery 1-3 years2)

PCD2.M110/M120

hardware version < H

2 × alkaline batteries size

LR03/AAA/AM4/Micro

1-5 years2)

PCD2.M110/M120

hardware version >= H

CR 2032 lithium battery 1-3 years2)

PCD2.M150/M170/M480 CR 2032 lithium battery 1-3 years2)

1) The PCD1.M110 has no hardware clock, so the buffer time is greater than it is for the PCD1.M120

2) 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 comissioning. Observe the polarity of the batteries:

 for alkaline batteries, the polarity can be seen on the socket
 insert CR 2032 coin cell in such a way that the Plus pole is visible
CPUs with alkaline or 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:
 the battery voltage is below 2.4 V or above 3.5 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.
The batteries are easy to locate on all CPU types.

PCD1.M130: PCD1.M135: PCD2.M110/120/150: