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Read more about RS485. Read more about RS485. But it does offer some more insight in the implementation that i suspect has ether been neglected or ignored by some big brands building RS485 devices. It only mentions failsafe, but avoids the topic of implementation as that is "application specific" (As a result every single transceiver manufacturer has come up with their own ideas - that may or may not be compatible to each-other) (It is better these days though. RS485 can be great but the standard is too vague in it's implementation to ensure compatibility. Stub length, termination, and biasing resistors can have a significant impact on the performance of the network. Define any network biasing I.e: What is the "correct" idle voltage on the bus? However; How anyone is able to make functioning R485 network based on a standard that barely covers the essentials is a mystery to me. Although the mbpoll is not available from the standard repositories, the README does well enough job explaining what to do, with some twists. The EIA once labeled all its standards with the prefix "RS" (Recommended Standard), but the EIA-TIA officially replaced "RS" with "EIA/TIA" to help identify the origin of its standards.

The Electronics Industry Association (EIA) has produced standards for RS485, RS422, RS232, and RS423 that deal with data communications. Suggestions are often made to deal with practical problems that might be encountered in a typical network. RS485 RS-485 is a standard that allows high speed data transmission along with multiple transmitters and receivers and this makes it able to be incorporated as a network solution. This allows either twisted pair cables to be used with terminal blocks, or Ethernet Cat5e or Cat6e cable to be used with RJ45 jacks. Various build options are possible including 4-wire serial, 1x10-pin female ComBoard header, or a 2x5-pin shrouded header for use with ribbon cables. A number of specifications use EIA-485 as the electrical standard, including SCSI-2, SCSI-3, BitBus, and Profibus. EIA-485 devices may be used in 422 circuits, but EIA-422 may not be used in 485 circuits (because of the lack of an Enable line). Up to 32 transmitters and 32 receivers may be interconnected in any combination, including one driver and multiple receivers (multi-drop), or one receiver and multiple drivers. It is very handy for anything that has an Ethernet port for the ModbusTCP, including devices like Raspberry Pi based controllers industrial controllers.

With 2 pairs of wires -- a dedicated "transmit" pair and a dedicated "receive" pair (similar to some Ethernet hardware), software can't tell the difference between RS-485 and RS-232. High Speed Ethernet or HSE and the "conventional" Ethernet both share the same physical and MAC levels , but use different protocols. However the other standards that have been introduced more recently provide higher levels of performance that are very useful in may applications. Repeaters may be used to extend the net to any number of devices. The number of loads, the termination resistance 60 ohms (120 ohms per side), and the required (turn-on) current of the receivers. RS485 Termination : 120 Ohm (Jumper selectable). RS485 drivers : Up to 1200 m using 26AWG twisted pair wire at 115.2 k Baud into 120 Ohm loads. RS485 Bias : 470 Ohm pull-up and pull-down (jumper selectable). RS485 Bias : 680 Ohm pull-up and pull-down (Jumper selectable).ตัว Converter สามารถ Auto Selectable Baud Rate ให้อัตโนมัติ , ด้าน RS485 มีขั้วต่อให้เลือกใช้ได้ทั้งแบบ สกรูขัน(Terminal) หรือ ขั้ว RJ-11, สามารถใช้งานเป็น Converter RS232 to RS422 ได้โดยการสลับ Dip Switch ภายในกล่อง , Converter ตัวนี้ผ่านการทดสอบ การใช้งานภายในโรงงานอุตสาหกรรมมาแล้วเป็นอย่างดี(Industrial Specification).

RS232 still being very widely used despite the fact that it has been in use for over 40 years. 15 years ago that was painful. We have been producing these converters based on FTDI technology, for over 15 years and have supplied major projects in Civil Engineering, the Military, Aerospace, and Nuclear Industries. The CB485 provides an RS-485 interface for microcontroller projects. The CB485 uses the ComBoard standard for interchangeable serial interface modules. With the 1x10 male header option, the CB485 can be used with solderless breadboards. In fault conditions they are protected to sustain common mode voltages up to peaks of 1KVdc. This isolation can be used in serial communications systems where high integrity data transmission and reception are required in an electrically severe environment. It also features a high-speed 115.2 Kb/s transmission rate, and supports various independent RS-232/485 Ports. RS485 is a hardware architecture that specifies only the electrical characteristics of transmitters and receivers, without endorsing any particular transmission protocol.

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