ABB AC500 PLC Hardware Manual page 1294

System Assembly, Construction and Connection
AC500 (Standard) > Handling of Accessories
Bus topology Point-to-point with RS-232 or bus topology with RS-485. Modbus is a master-slave protocol.
For further information on Modbus see chapter Communication with Modbus RTU.
2.6.5 Handling of Accessories
This section only describes accessories that are frequently used for system assembly, connec-
tion and construction. A description of all additional accessories that can be used to supplement
AC500 system can be found in the Hardware PLC device description.
2.6.5.1 TA521 - Lithium Battery
● Manganese dioxide lithium battery, 3 V, 560 mAh
● Non-rechargeable
Purpose The TA521 lithium battery is the only applicable battery for the AC500 processor modules
Ä Chapter 1.2.2.1 "PM57x (-y), PM58x (-y) and PM59x (-y)" on page 65 and PM56xx. It cannot
be recharged.
Purpose The processor modules are supplied without lithium battery. It must be ordered separately. The
TA521 lithium battery is used for data (SRAM) and RTC buffering while the processor module is
not powered.
See AC500 Battery.
The CPU monitors the discharge degree of the battery. A warning is issued before the battery
condition becomes critical (about 2 weeks before). Once the warning message appears, the
battery should be replaced as soon as possible.
Handling ● Do not short-circuit or re-charge the battery! It can cause excessive heating and explosion.
Instructions
● Do not disassemble the battery!
● Do not heat up the battery and not put into fire! Risk of explosion.
● Store the battery in a dry place.
● Replace the battery with supply voltage ON in order not to risk data being lost.
● Recycle exhausted batteries meeting the environmental standards.
Battery Lifetime The battery lifetime is the time, the battery can store data while the processor module is not
powered. As long as the processor module is powered, the battery will only be discharged by its
own leakage current.
1294 3ADR010121, 13, en_US 2019/04/17