Transmission speed refers to the rate at which data is transferred between devices using the RS485 cable. The transmission speed of RS485 cables can vary depending on factors such as cable length, baud rate, and the quality of the cable itself. Overall, RS485 cables are known for their robustness, reliability, and versatility, making them a popular choice for industrial automation, building control systems, and other applications requiring stable and secure communication over extended distances. The termination also includes pull up and pull down resistors to establish bias for each data wire for the case when the lines are not being driven by any device. The latest point of view on RS485 cables includes advancements in design to support higher data rates and improved resistance to environmental factors such as temperature fluctuations and moisture. In practice, Cat 5 cables have been used successfully in many installations, but there are some concerns. Well, either you know that your grounds are at the same voltage due to other connections, or you provide a ground connection for a reference along with the data wires. I thought that the whole idea was that the 2 data wires carried a differential voltage. RS-485 cables typically have two twisted pairs of wires for differential signaling, allowing for greater immunity to electromagnetic interference.
What is the lifetime of these types of cables? From the computer to the controller, there are multiple options, and since the controller is usually within sight of the computer, there is no need to reinvent the wheel, so to speak, on that. Note if they were local grounds then there would be a number in them like on the right hand side. Note that they have a shield grounded at one end (presumably to avoid earth loops). I guess if nothing else, I could use trial and error to find which one works; while not ideal, it may be my only option. I’ll see if I can find more information on the protocol. Based on information from the Wikipedia page you posted, it looks like there are a limited number of communication standards transmitted over 485, with one being pointed out as the most frequently used. Your 485 to 232 converter should have some information in the manual to tell you what cabling is needed to connect it, but since you are asking, it obviously doesn't say, or isn't clear. Star and ring topologies are not recommended because of signal reflections or excessively low or high termination impedance. Grounds between buildings may vary by a small voltage, but with very low impedance and hence the possibility of catastrophic currents - enough to melt signal cables, PCB traces, and transceiver devices.
The most common cable type is Cat 5e-UTP (unshielded twisted pair) which may work over shorter distances in less demanding applications with low EMI noise levels. 60%, UL Type CMP/CL3P 24 AWG. Electrical signaling is balanced, and multipoint systems are supported. Yes there is, they all use the same symbol so they are all connected together. Or 4 wires and there twisted pairs. Polarity of the wires must be observed. Care must be taken that an SC connection, especially over long cable runs, does not result in an attempt to connect disparate grounds together - it is wise to add some current limiting to the SC connection. This means that in order to work properly, you must constrain the voltages to those levels. I work for an Automation Company named TCS. This allows RS-485 to implement linear bus topologies using only two wires. Not quite, the twisted pair ensures that any signal picked up is common to both wires. No, if this induced signal is also picked up by the ground wire then the differential is still preserved.
Without termination resistors, signal reflections off the unterminated end of the cable can cause data corruption. With Modbus, BACnet and Profibus, A/B labeling refers A as the negative green wire and B as the positive red wire, in the definition of the D-sub connector and M12 circular connector, as can be seen in Profibus guides. If A is negative with respect to B, the state is binary 1. The reversed polarity (A positive with respect to B) is binary 0. The standard does not assign any logic function to the two states. For an on, space or logic 0 state, the driver's A terminal is positive relative to the B terminal. The issue also exists in programmable logic controller applications. Rs232 is only an option for pc to controller. Otherwise RS232 would be my next best option. From what I’ve read, the modbus is a protocol for communication between a computer and an RS485 device, if this is true, I shouldn’t need a modbus lib for this application. Some laptops have the ability to disable them in the bios at boot up which would cause your communication issues.
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