1, giving the sensor signal:
A the wiring on site is not standardized, and the control line, signal line and high voltage are mixed together, which will cause signal interference when the high-power equipment is started, and this situation will also occur. I suggest you check the direction of the Frophibus line. B indicates that there is something wrong with the module, or the connecting wire is white, and the module is powered on and grounded.
2. The signal of the sensor is not extinguished.
Check the wiring, power supply and necessary grounding of the sensor. SF light indicates system failure, including many types. The specific fault types can be viewed online through CPU.
The method is as follows: after establishing an online connection with PLC, select the station to be checked in SIMATIC Manager, execute the menu command PLC → diagnosis/setting → module information, open the module information window, and display the CPU information of this station in the diagnosis buffer option of the module information window.
The list of events in CPU is given. Select an event in the Event window, and the gray Details window below will display the details of the selected event. Diagnostic buffer can be used to analyze system errors, find out the reasons for downtime, and classify diagnostic time.
Extended data:
Installation and maintenance of Siemens plc;
If overload occurs, the voltage will automatically drop, and the input at this time will not work for the programmable controller. The input points of each type of PLC are specified. For each unused input point, there is no power consumption, so in this case, the external power supply capacity of the 24V power terminal can be increased. The empty terminal of FX series PLC cannot be used under any circumstances.
2.5 input wiring PLC- usually accepts switch signals input by travel switches and limit switches. The input terminal is the port of load conversion signal between PLC and external sensor. Input wiring usually refers to the wiring between external sensors and input ports. The input device can be any passive contact or open collector NPN tube.
When the input device is turned on, the input terminal is turned on, the input line is closed, and the LED indicating the input is lit. The primary circuit and the secondary circuit at the input end are isolated by photoelectric coupling. The secondary loop is equipped with RC filter to prevent PLC misoperation caused by input contact jitter or electrical noise of input lines in series.
If a diode is connected in series in the input contact circuit, the voltage across the series diode should be less than 4V. If reed switches with light emitting diodes are used, the number of diodes in series should not exceed two.
External input wiring should also pay special attention to the following points:
(1) input wiring is generally not more than 30m. However, if the environmental interference is small and the voltage drop is not large, the input wiring can be appropriately longer.
(2) The input and output lines cannot use the same cable, and the input and output lines should be separated.
(3) The width of the pulse signal acceptable to the programmable controller should be greater than the scanning period. 2.6 Output connection (1) Programmable controller has three forms: relay output, thyristor output and transistor output.
(4) Output terminal wiring is divided into independent output and public * * * output. When the output relay or thyristor of PLC acts, two outputs with the same number are connected. Different types and voltage levels of output voltages can be used in different groups. However, the outputs in the same group can only use the same type of power supply with the same voltage level.
(5) Because the output element of PLC is packaged on the printed circuit board and connected to the terminal board, if the load connected to the output element is short-circuited, the printed circuit board will be burnt out, so the output element should be protected with a fuse.
(6) When the relay is used for output, the inductive load will affect the working life of the relay, so the working life of the relay is required to be longer.
(The output load of PLC may cause noise interference, and measures should be taken to control it.
In addition, for dangerous loads that can cause harm to users, in addition to consideration in the control program, an external emergency stop circuit should be designed so that when the programmable controller fails, the power supply of the load that causes harm can be cut off.
References:
Baidu encyclopedia-Siemens