According to the technical engineer who has been engaged in this technical work for a long time: 1RS485 communication short distance (within 800m) can generally use unshielded ordinary twisted pair 2 When the interference is heavy, the shielded twisted pair can be used (the shield is suspended) / or only one end of the ground - to be separated from the "strong electric ground", especially the "inverter ground") 3 signal ground is generally suspended (not wired), if the grounding is not good, but can not communicate properly.
Most netizens are also above this opinion. However, some netizens believe that the interconnected devices should be common; otherwise, if the receiving end has a higher common mode input, it may damage the receiving device.
In most cases, when connecting the RS-485 communication link, simply connect the "A" and "B" ends of each interface with a pair of twisted pairs, and leave the signal ground - this connection The method works fine in many situations, but you should pay attention to the following two problems:
(1) Common mode interference problem: The RS-485 interface receives the input signal in a differential manner, and does not need to detect the signal relative to a certain reference point. The system only needs to detect the potential difference between the two input lines. However, people often overlook that the receiver has a certain common-mode voltage range. The common-mode voltage range of the RS-485 receiver is -7~+12V. Only when the above conditions are met, the entire network can work normally. When the common mode voltage in the communication line exceeds the range, the communication is stable and reliable, and even the interface is damaged.
(2) Electromagnetic radiation problem: the common mode part of the driver output signal needs a return channel. If there is no low-resistance return channel (signal ground), it will return to the source end in the form of radiation, and the whole bus will be like a huge The antenna radiates electromagnetic waves outward. Scale Inhibitor
Scale inhibitors are a class of agents that can disperse insoluble inorganic salts in water, prevent or interfere with the precipitation and scaling functions of insoluble inorganic salts on metal surfaces, and maintain good heat transfer effects of metal equipment.
Scale inhibitors can remove scale and prevent the formation of scale, improve heat exchange efficiency, reduce electricity or reduce fuel consumption; Water treatment can also reduce sewage discharge, improve water utilization, generally can save more than 60%,in line with the global demand for energy conservation and emission reduction.
The role of scale inhibitors is divided
into four parts: chelating and solubilization, agglomeration and dispersion,
electrostatic repulsion and crystal distortion. And in the laboratory
evaluation test, dispersion is a remedy for cheosylation, and lattice
distortion is a remedy for dispersion.
According to the polymeric composition of
the scale inhibitor, it can be divided into two categories: natural polymer
scale inhibitor and synthetic polymer scale inhibitor. The synthetic polymer
scale inhibitor can be further divided into four kinds of carboxylic acid
polymer scale inhibitor, sulfonic acid polymer scale inhibitor, phosphorus-containing
polymer scale inhibitor and environmentally friendly scale inhibitor.
Scale Inhibitor In Water,Antiscaling Compound,Anticrustator In Water,Scale Prevention
WUHAN RUISUNNY CHEMICAL CO. LTD , https://www.ruisunny-chem.com