The selection principle of the S7-300 PLC is based on the functions and capacities required for the production process, taking into account the convenience of maintenance, the versatility of the spare parts, and the ease of expansion and the presence or absence of special functions. Let's introduce the main points of the use of Siemens S7-300 series PLC to the introduction of the Aichi Mall Xiaobian.
(1) Anti-interference measures. Clutter from the power line can cause system voltage distortion, resulting in overvoltage, overload, overheating and even burning of components in the system, causing PLC and other control devices to malfunction. Therefore, it is better to provide anti-interference facilities such as shielding transformers or power supply filters at the power inlet. Among them, the ground of the power filter should be connected to the central protection ground with the shortest line. For DC power supplies, a differential capacitor can be added for interference suppression.
(2) Protective grounding. The protective ground of the switchboard can be connected with a protective wire of not less than 10 mm2; the adjacent control cabinets should also be in good contact and reliably connected to the ground. At the same time, lightning protection grounding should be done. Generally, the bus cable can be used with shielded cable and the shielding layer is grounded at both ends, or the analog signal cable is shielded by two layers, and the outer shield is grounded at both ends. In addition, to prevent inductive lightning from entering the system, a surge absorber can be used.
(3) Do a good signal shielding. Signal shielding is critical, and shielded cables can generally be used to transmit analog signals. Note that when multiple analog cables are used to share a multi-core shielded cable or when two shielded cables are used, the signals must be shielded. Moreover, one end of the shield of the cable (generally at the control cabinet end) should be reliably grounded.
( 4) When there is no or impossible hard point setting on the site , you can use the soft button method on the operation interface to solve the problem of selection or control mode selection. In addition, it is better to use a signal line directly connected to the inverter, smart meter, etc.
(5) The use environment of the PLC should be reasonably configured to improve the anti-interference ability of the system . The specific measures are: away from high-voltage cabinets, high-frequency equipment, power screens, and high-voltage lines or high-current power units; communication cables and analog signal cables should not share cable trenches with other screens (disks) or equipment; fluorescent lamps are not used in PLC cabinets. . In addition, although PLC is suitable for industrial sites, it should also avoid direct vibration and shock, direct sunlight, oil mist, rain, etc. in use; do not apply in the vicinity of corrosive gas, excessive dust, and heating body; avoid conductive impurities The object enters the controller.Industrial Dtu,Industrial 4G Dtu,Industrial 2G 3G Module 4G Dtu,4G Industrial Modem Dtu
Shenzhen MovingComm Technology Co., Ltd. , https://www.movingcommiot.com