Communication cable RS485 2 * 2 * 20AWG

Description :

　　RS485 communication cables generally use twisted pair cables, but in environments with higher requirements, shielded twisted pair cables should be used. When using RS485 communication lines, the cable length between the host (calling device) and the 485 port of the instrument is inversely proportional to the baud rate of data signal transmission for a specific transmission line; This length is mainly affected by signal distortion and noise. In theory, the transmission distance of RS485 communication cable can reach 1200 meters, but in practical applications, the transmission distance should be less than 1200 meters, and the specific length is affected by the surrounding environment.

　　Characteristics of RS485 communication cable: The characteristic impedance of RS-485 communication cable is 120 ohms, the conductor is 2 * 24AWG multi stranded tinned copper wire, PE insulation medium, 100% coverage of aluminum foil/polyester composite tape and 90% coverage of tinned copper wire, a total of 2 layers of shielding, with independent grounding wire and industrial gray PVC outer sheath.

　　RS485 communication line structure:

　　1) Conductor: Stranded tinned copper wire with multiple strands, 7 per strand, each conductor wire diameter of 0.30mm, a total of four conductors, outer diameter: 0.91+/-0.03mm

　　2) Insulation: Solid core PE insulation, outer diameter: 1.90+/-0.03mm

　　3) Shielding: Aluminum foil shielding

　　4) Drainage wire: multi stranded tinned copper wire, 7 per strand, each conductor wire diameter of 0.30mm, a total of one strand, outer diameter: 0.91+/-0.03mm

　　5) Second shielding: Aluminum magnesium braided mesh shielding, with a coverage rate of 55%

　　6) Inner sheath: black PVC, OD: 8.0mm+/-10%

　　After testing, the communication distance of the RS485 communication line is about 1219M, and the transmission rate is 10Mb/S. The transmission rate is inversely proportional to the transmission distance, and the communication distance can only be achieved at a transmission rate of 100Kb/S. If a longer distance needs to be transmitted, a 485 repeater needs to be added. The RS485 bus generally supports 32 nodes. If a specially designed 485 chip is used, it can reach 128 or 256 nodes, and can support up to 400 nodes.

　　Control cables are mainly used for transmitting control signals, so they are PVC insulated and PVC sheathed control cables suitable for industrial and mining enterprises, energy and transportation departments, and for controlling and protecting circuits with AC rated voltage below 450/750 volts.

　　The long-term allowable working temperature of the control cable conductor used in coal mines is 70 ℃, and the cable laying temperature should not be lower than 0 ℃. The allowable bending radius for control cables used in coal mines: For cables with armor or copper tape shielding structures, it should not be less than 12 times the outer diameter of the cable. For flexible cables with a shielding layer structure, it should not be less than 6 times the outer diameter of the cable. For unarmored cables, the outer diameter should not be less than 6 times that of mining cables.

　　Precautions for installation and wiring of control cables:

　　1. Under the eaves. Standard LAN cables can only be used when not directly exposed to sunlight or ultra-high temperatures, and it is recommended to use pipelines. Ultraviolet (UV) - Do not use cables without UV protection in direct sunlight environments;

　　2. On the exterior wall. Avoid direct sunlight on the wall and human damage. Heat - The temperature of cables in metal pipes or cable trays is very high, and many polymer materials will reduce their service life at this temperature;

　　3. In a pipeline (made of plastic or metal). If in a pipeline, pay attention to the damage of plastic pipes and the thermal conductivity of metal pipes. Mechanical damage (repair cost) - Fiber optic cable repair is very expensive, requiring at least two terminations at each breakpoint;

　　4. Suspended applications/overhead cables. Consider cable sag and pressure. Whether the cable is directly exposed to sunlight;

　　5. Directly laying in underground cable trenches has a limited control range. The installation of cable trenches should be checked regularly for dryness or moisture levels. Grounding - If the shielding layer of the control cable needs to be grounded, the corresponding standards must be followed;

　　6. Underground pipelines. For future upgrades, cable replacement, and isolation from surface pressure and surrounding environment, installing auxiliary pipelines for isolation is a better method. But don't expect the pipeline to remain dry forever, as this will affect the choice of cable type. Water - Moisture in twisted pair cables in a local area network can increase the cable's capacitance, thereby reducing impedance and causing near end crosstalk issues.

　　Tianjin Cable Factory Branch has always been committed to serving our customers with the principles of "excellent quality, reasonable price, and thoughtful service"; Sincerely welcome new and old customers to visit.

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• Communication cable RS485