Siemens PLC communication failure, BF, SF light on the cause of the failure and maintenance

SiemensplcSFWhen the light is red, it means a system failure, which is the abbreviation of English (SYSTEM FAULT), Caused by internal addressing errors, exceeding the programming address area, damaged modules, loose plug-ins, etc. Clear the programs in PLC first, SF SF SF FONT>If the light is still on, it means that the hardware is broken. If it is not on, there may be a problem with your program. Check it onlinePLCInformationS7-300PLCSFlight is on and BFlight is flashing, it must be distributed fieldbusPROFIBUS-DPcommunication orDPSlave stations such asABBInverter problems, do not suspect other software and hardware problems;PLCIf there is a problem with the analog module, justPLCSFThe light is on (such as with hardware The diagnostic analog module can set the analog signal disconnection, over-range, etc.), without causing SFandBF lights are on at the same time; according to the above analysis, focus on inspectionS7-300PLC Whether the hardware configuration is consistent with the actual hardware (hardware order number and firmware version number), DPWhether the address setting of the slave station is consistent with the configured address; if there is no problem with the configuration, after completing the hardware configuration, you must execute Save and compile, if there is no error, a new system data block will be generated and downloaded to PLC; checkPROFIBUSWhether the cable and its communication connector are correct,PROFIBUS There are two wires in the cable, one is red connectionPROFIBUS FONT>PROFIBUSBconnection, the other one is green and connected to the networkAconnection (incoming lines are B1A1, the outlet isB2, A2), cannot be reversed; if there is only one electrical network segment, that is, from S7-300PLCX2port (PROFIBUS-DPport) There is only one PROFIBUScable, then the first and last (respectivelyS7-300PLCand lastDPSlave) The red terminal resistor of the network connector must be set“ON”Position, middleDPThe network connector on the slave station must be set“OFF”position; ifABBThe inverter is not powered on, and your hardware configuration includes the inverter as a DPslave, then S7-300PLCAfter power on, no detectionABBInverter, soPLCSFlight is on, and BFlight is flashing, this is a normal phenomenon; generallyPLC and touch screen usingMPIcommunication protocol, can be connected with PLCto run at the same time, and can be configured without FONT>MPIcommunication, global dataMPICommunication and ConfigurationMPICommunication. Due to the MPIS7-300PLCand the touch screenMPI FONT>Communication does not needSTEP7Software configuration does not need to write any program, just set the relevant communication parameters on the touch screen configuration software, so there is no problem with the touch screen CauseSFandBFlights on;

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