Chapter 4. CPU Operation176 PACSystems* RX7i, RX3i and RSTi-EP CPU Reference Manual GFK-2222AD4.11.3 Power Cycle Operation with an Energy PackEnergy Packs offer distinct advantages over batteries:a) significantly longer life cyclesb) they are more reliablec) flammability during shipment is not an issued) in their end-of-life phase, their decline is a lot more gradual.The system design includes the ability of the CPU and the Energy Pack to monitor each other in real time.This permits the user to monitor alarms and thereby determine when to replace a capacitor pack. Thecapacitor pack is normally replaced while the CPU is powered on, giving it time to charge up before anysubsequent loss of power. Users should target periods which are expected to be free from electricalevents, such as thunderstorms, to carry out such work. Capacitor packs may also be replaced whilepower is off.When power is lost, the Energy Pack supplies current and maintains voltage levels for a period of timesufficient to permit the connected CPU to save all dynamic memory to non-volatile memory.When power is restored, the CPU will not start running its application until the Energy Pack signals thatit is fully charged. The CPU will then resume operation using the contents of memory retained at theprevious loss of power event. The Energy Pack charges continuously during normal operation.The RX3i and RX7i product lines encompass several different Energy Packs, so it is important to usecompatible products:CPU IC695CPE400 IC695CPE330 IC695CPE302IC695CPE305IC695CPE310ICRXICTL000Energy Pack IC695ACC403 IC695ACC402 IC695ACC400 ICRXIACCEPK01Capacitor Pack IC695ACC413 IC695ACC412 IC695ACC400 ICRXIACCCPK01Connecting Cable IC695CBL003 IC695CBL002 IC695CBL001 ICRXIACCCBL01Documentation GFK-3000 GFK-2939 GFK-2724 GFK-2741User memory is preserved only if the compatible Energy Pack is connected (and charged) at power-down.If the Energy Pack is connected at power-up, the CPU waits for it to charge up before beginning normaloperations. For CPE330/CPE400, this typically takes up to 90 seconds.In the event the Energy Pack fails to charge up in a reasonable amount of time, or is absent, the CPU willtime out the wait period and will then commence operations without the Energy Pack. When this occurs,the CPU is vulnerable to loss of memory, should another power failure occur. It is critical to monitor thestatus bits shown in Energy Pack Status Bit Operation so that human intervention can be summoned.Removing or reconnecting the Energy Pack while the connected CPU is powered off has no effect on thepreservation of user memory.Note: Because the Time of Day (TOD) clock is powered by a separate Real Time Clock battery inCPE302/CPE305/CPE310/CPE330/CPE400, the Energy Pack has no effect on the CPU TOD value.
