Siemens PLCS7-300 common fault maintenance
1.The PLC power-on indicator is not displayed.
In the past, many cases of this kind of fault were originally DC 24V input power supply, but the user was connected to AC 220V, it is conceivable that this situation will burn the fuse and switch tube, and the capacitor switch tube will be heavy.
The normal 220V power supply PLC module is not displayed when powered on, and the power board is generally damaged (the lowest board) is nothing more than several reasons: 315A fuse, square rectifier bridge and diode. The core component belongs to TOP247FN.
2.The PLC will be powered on and will be powered off for a while.
In the past maintenance process, this kind of failure was encountered many times, and at first it was suspected that it was a capacitance (400V 100UF) problem, but after the replacement, the fault was still the same. The top247FN is replaced by a disconnected device, and it runs normally after powering on.
4.What is the input resistance of the analog mask EM235?
The size of the input resistance depends on the type of input you choose, if you choose a voltage input, the input impedance is not less than 10 megaohms;If the current input is selected, the input immunity is 250 ohms.
5.What does the measured value mean when using the EM231RTD module?
When you apply the EM231RTD module, divide its measurement by 100 is the actual temperature value. The range that the module itself is capable of measuring is -32768 to 32767 degrees Celsius, but the range of the actual measured value depends on the measuring range of the sensor and the actual temperature.
Siemens 300PLC repair failure: Wrong power maintenance, MPI port can not communicate, DP port can not communicate, SF light on, BF light on, DC5V light is not on, BATF light is on, STOP light is always on, RUN light is not on, can not start, indicator light flashes, indicator light does not light up, PLC decryption and other fault maintenance services.
Siemens PLC digital module failure: no input and output, the input light is not on, the input terminal cannot be controlled, the indicator light is always on, the relay is broken for maintenance, and the fuse is burned out for maintenance.
Siemens PLC analog module failure: no input and output at the point, SF light on, indicator light always on, etc.