After programming, a syntax check can be performed to help correct the program syntax errors. 2) monitoring operation: PLC is connected with upper computer through RS232-C interface, the computer can monitor the work of PLC, observe the state of any work position, read all data, and force some work position to be ON or OFF. Also may according to the need convenient and the coal mine local area network link. 3) file management: the program can be stored as disk files, these files can be managed in accordance with the Computer File Management, program printing, and so on. 4) on-line Modification: Monitoring run-time need to modify the control program or found problems in the program, in addition to offline modification, in the case of not too many problems, but also allowed to change the program again. This kind of operation, while changing, not only does not delay the work of PLC, but also can directly find and remove the fault, is a more convenient debugging and improving procedures on the spot. 4. on-site anti-interference measures, because of the particularity of underground power supply in coal mine, the influence of all kinds of interference on the system must be considered. anti-interference is a crucial content in the system design, so corresponding measures are taken from the design of software and hardware to enhance the anti-interference ability of the system. The main interference source in the mine is caused by the power supply and grounding system. For example, the underground coal mine uses the transformer neutral point ungrounded power supply way, the power supply system contains the high-order harmonic component to be big; the underground coal cutter, the main water pump, the transport machine and so on big, the medium-sized electrical equipment use many and the work starts frequently, the electric network voltage fluctuation is big; the direct current overhead line electric locomotive runs in the tunnel, the rail as an electrode its inflow earth stray current is many; the Electric Locomotive Pantograph and the overhead line contact bad produces the electric spark to cause the electromagnetic radiation interference and so on. The disturbance caused by the power supply and the grounding system is very disadvantageous to the normal work of the system, so we take some measures to prevent the disturbance: 1) to the disturbance from the distribution system, add an anti-disturbance AC voltage stabilizer to the 220V output stage of the original distribution panel, so as to minimize the disturbance of the distribution