S7-300 PLC CPU Panel features

1, load power supply module


Load power supply module is used to convert AC 220V power supply DC 24V, for use by the CPU and I/O module and other modules.

2, backup battery


Backup battery in the PLC is the role of power, to ensure the normal operation of the real-time CPU clock, and you can save a user‘s programs and data (in RAM). Some lower-end CPU because there is no real time clock, there is no backup battery.

3, DC 24V terminals


CPU outputs a DC 24V,L+ DC 24V anode and cathode respectively and m. Can be used as a CPU switch signal input or external power components.

4, mode selector switch


Mode selector switch used to select the operation mode of the CPU. The switch is a key switch, altering the way it needs to insert the key to prevent unauthorized people from changing the CPU operation mode.


Mode selector switch position as follows:


(1) RUN-P (runprogram) location: CPU not only execution of the program can also read and modify procedures and altering the way;


(2) RUN (run) position: CPU execution of the program can read the program, but you cannot modify the program;


(3) STOP (stop) position: CPU does not perform procedures, can read and modify procedures;


(4) the MERS (MEMORY CLEARED) location: can reset the memory, the CPU back to the initial state. This position cannot be maintained, when after the release and return to the STOP position.

5, status and fault led


(1) SF (system fault indicator, red): CPU hardware failure or a software error occurred frequently;


(2) the BATF (battery, red): low battery voltage or no batteries are often lit;


(3) DC 5V (+5V power supply, green): CPU and S7-300 bus +5V power supply normal bright at times;


(4) FRCE (mandatory instructions, yellow): at least one I/O is often by force;


(5) RUN (running instructions, green): CPU in RUN run as often, when booting with the 2Hz frequency of shiny, shiny HOLD State of 0.5Hz frequency;


(6) STOP (stop instructions, yellow): CPU at a STOP, HOLD the State often; request a memory reset blinking at a frequency of 0.5Hz being reset to 2Hz frequency flicker;


(7) the BUSF (bus fault indication, red): Profibud-DP interface to hardware or software failure is often light.

6, memory card


Memory card when the electricity was used to save user programs and data, you can extend the storage capacity of the CPU.

7, MPI interface


MPI interface for CPU and other PLC, PG/PC (PG/PC), OP (operator interface) via MPI network communications.

8, front connector


Front connector is used to connect sensors and actuators to the signal module, front cover (9).