Siemens S7-200plc how to set power down to maintain - Database & Sql Blog Articles

SMD aluminum electrolytic capacitor

ESD TVS electrostatic protection tube 0201 package 3.3V ultra low capacitance ESD

Brand AVX TPSE226M035R0125 Low impedance tantalum capacitor AVX 22

Electronic scale crystal oscillator 3.2*2.5mm 3225 16M (16.000MHZ) 12PF 10PPM 20PPM 30PPM

MOS power IC full range

How to set the Siemens S7-200 series plc to maintain power-down, the existing two data MW100, MW102 need to save how to set.
A: It is OK to use MW100 and MW102 as the data in MB0~MB13. This value is a fixed value. Set it in the data save in the system fast, set it up and download it to the PLC. However, this is maintained by using a capacitor, which is about 120 hours.
Powered by supercapacitor, the hold time is: 190 hours / typical value (minimum 120 hours at 40 ° C)
When using the S7-200, the following data retention methods are available:

The CPU's built-in supercapacitor provides power buffering for data and clock retention when the power-down time is not too long.
A CPU card can be attached to the CPU to cooperate with the built-in capacitor to provide a power setting system block for clock and data retention for a long time. The 14 bytes of data in the M area are automatically saved when the CPU is powered off. Data that does not need to be changed is defined in the data block. Download to the CPU can be permanently saved. User programming uses the corresponding special register function to write data to the EEPROM for permanent storage.
The built-in EEPROM memory of the CPU is used to permanently store data, including all V memory areas, partial M memory areas (MB0-MB13), and timers (TONR) that correspond one-to-one with the RAM data area.

For example, the VW100 (RAM) of the V memory area has its exclusive corresponding address in the EEPROM. When the data is written from the EERPOM to the V memory area, the target address is VW100.

Data can be written to the EEPROM data area as follows:

The initial value of the V data area memory location is defined in the DataBlock of the programming software Micro/WIN. When the data block is downloaded, these values ​​are also written to the corresponding EEPROM unit.
Programmatically write data from V memory area to EEPROM with special memory SMB31, SMW32
Set the data hold function in the SystemBlock to automatically write the contents of MB0-MB13 to the EEPROM when the CPU is powered off.

There are three ways: super capacitor hold, backup battery hold, EEPROM hold. among them

1, the super capacitor can only be saved for five or six days, and the super capacitor exists in the S7-200CPU;

2. The backup battery can be kept for about 200 days and needs to be purchased.

3, EEPROM can be permanently maintained, but the EEPROM can only automatically save the maximum of 14 bytes of MB0-MB13 set by the system. The V area needs to be programmed into the EEPROM. If the V area has a piece of initialization data, it can pass. The "data block" is assigned and downloaded to the PLC.