R485, R232, and computer communication issues

232 is for short distances, while 485 is for longer distances; you can search on Baidu – there’s a lot of information available.

RS232 transmission is point-to-point, with a transmission distance of only 15 meters. RS485 transmission supports point-to-multipoint communication, with a transmission distance of up to 1800 meters (using half-duplex transmission)

Thank you! Can we add each other on QQ to communicate more? 270964252, mine 3# paul688688

Ordinary computers do not have RS485 interfaces, so an RS232/RS485 converter is required. --------※------------※-------------※--------------- The following suggestions are intended to be helpful: 1. Using dedicated RS485 cables with impedance matching and low attenuation is more conducive to ensuring reliable communication. The following is generally recommended: standard twisted-shielded cable STP-120Ω (for RS485 & CAN), one pair with 20 AWG wire, and an outer diameter of around 7.7 mm. Suitable for indoor use, pipelines, and general industrial environments. When in use, one end of the shielding layer must be grounded! Standard twisted-shielded cable STP-120Ω (for RS485 & CAN), one pair, 18 AWG; the outer diameter of the cable is around 8.2 mm. Suitable for indoor use, pipelines, and general industrial environments. When in use, one end of the shielding layer must be grounded! Armored twisted-pair shielded cable ASTP-120Ω (for RS485 & CAN), one pair 18 AWG, with an outer diameter of around 12.3 mm. It can be used in areas with severe interference, frequent rodent problems, as well as those with requirements for lightning protection and explosion prevention. When in use, it is recommended to ground both ends of the armored layer, and ground one end of the innermost shielding layer! The CC-Link bus cable is a 3-core twisted shielded cable with a characteristic impedance of 110±10Ω; the domestic model specification is STP-110Ω (for CANopen & CC-Link), 3C×20AWG. When in use, the shield should be grounded at only one end! 2. A termination resistor (usually 120Ω) should be added if the transmission distance exceeds 300 meters. 3. Inverters, power cables, transformers, high-power motors, etc., often generate low-frequency interference, and such interference cannot be eliminated by cables with shielding layers made of highly conductive materials, including original imported cables. Only shielding layers made of high magnetic permeability materials (such as steel strips and steel wires) can effectively suppress low-frequency interference. The most common method is to cover the cable with a steel tube, or to use armored cables made of materials with high magnetic permeability – ASTP-120Ω (for RS485 & CAN), 1 pair, 18 AWG. The equivalent interference frequency caused by lightning is around 100 kHz, which falls within the category of low-frequency interference. Article 6.3.1 of the \"GB50057-94 Code for Design of Lightning Protection of Buildings\": ......In the space to be protected, when shielded cables are used, their shielding layers shall be equipotentially connected at least at both ends and preferably at the boundaries of the lightning protection zones. When the system requires equipotential connection only at one end, two layers of shielding shall be used, with the outer shielding layer being treated in accordance with the aforementioned requirements. The \"GB 50217-2007 Cable Design Code\" contains similar statements; see: http://www.gongkong.com/Forum/ForumTopic.aspx?Id=4-8F2B-47446DC42DCE

Ordinary computers do not have RS485 interfaces, so an RS232/RS485 converter is required. --------※------------※-------------※--------------- The following suggestions are intended to be helpful: 1. Using dedicated RS485 cables with impedance matching and low attenuation is more conducive to ensuring reliable communication. The following is generally recommended: standard twisted-shielded cable STP-120Ω (for RS485 & CAN), one pair with 20 AWG wire, and an outer diameter of around 7.7 mm. Suitable for indoor use, pipelines, and general industrial environments. When in use, one end of the shielding layer must be grounded! Standard twisted-shielded cable STP-120Ω (for RS485 & CAN), one pair, 18 AWG; the outer diameter of the cable is around 8.2 mm. Suitable for indoor use, pipelines, and general industrial environments. When in use, one end of the shielding layer must be grounded! Armored twisted-pair shielded cable ASTP-120Ω (for RS485 & CAN), one pair 18 AWG, with an outer diameter of around 12.3 mm. It can be used in areas with severe interference, frequent rodent problems, as well as those with requirements for lightning protection and explosion prevention. When in use, it is recommended to ground both ends of the armored layer, and ground one end of the innermost shielding layer! The CC-Link bus cable is a 3-core twisted shielded cable with a characteristic impedance of 110±10Ω; the domestic model specification is STP-110Ω (for CANopen & CC-Link), 3C×20AWG. When in use, the shield should be grounded at only one end! 2. A termination resistor (usually 120Ω) should be added if the transmission distance exceeds 300 meters. 3. Inverters, power cables, transformers, high-power motors, etc., often generate low-frequency interference, and such interference cannot be eliminated by cables with shielding layers made of highly conductive materials, including original imported cables. Only shielding layers made of high magnetic permeability materials (such as steel strips and steel wires) can effectively suppress low-frequency interference. The most common method is to cover the cable with a steel tube, or to use armored cables made of materials with high magnetic permeability – ASTP-120Ω (for RS485 & CAN), 1 pair, 18 AWG. The equivalent interference frequency caused by lightning is around 100 kHz, which falls within the category of low-frequency interference. Article 6.3.1 of the \"GB50057-94 Code for Design of Lightning Protection of Buildings\": ......In the space to be protected, when shielded cables are used, their shielding layers shall be equipotentially connected at least at both ends and preferably at the boundaries of the lightning protection zones. When the system requires equipotential connection only at one end, two layers of shielding shall be used, with the outer shielding layer being treated in accordance with the aforementioned requirements. The \"GB 50217-2007 Cable Design Code\" contains similar statements; see: http://www.gongkong.com/Forum/ForumTopic.aspx?Id=4-8F2B-47446DC42DCE

What was said above is quite good. Pay attention to the protocol