If an existing standard has some value to you, then you might have a look at PoE. You might make it work anyway, with a bit of stuffing at the protocol level, or it might "just work" with sparse communication and a receiver that interprets 0V differential as idle. 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. The USB-RS485-PCBA converter provides a USB to RS485 serial interface with a simple USB type A connector and PCB for easy integration into a design or as the basis of a converter cable. The cable recommended in this type of connection is the Belden 9842, which has 2 twisted pairs. 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. All the other Master Bricks with RS485 Extension must not have a USB, Ethernet or WIFI connection (they can use a USB Power Supply).

So take advantage of that and let your systems MCUs implement heart beat handshaking directly though the RS485 communications layer using appropriately designed small packets. But I notice that he describes using a (different) RS-485 to USB converter and splicing from the Ethernet cable to the converter, rather than using the converter cable that ships with the charge controller. The device ships with an Ethernet RS-485 communication interface as well as a RS-485 to USB cable, which is said to be able to communicate with a PC using proprietary Windows based software (and driver, I think). There is a huge benefit of the RS-485 electrical layer protocol that allows for long distance communications in the presence of multiple volts of common mode voltage differences between the two ends. One uses the data lines for 10/100 Ethernet, so that there are still 2 unused pairs in that cable. This is often used by switches and other networking gear that uses the data lines anyway.

Modem to modem lines often use 1200, 4800, 9600, 14400, 28800, 33600, and 56000 baud. What RJ11 cables should I use with RS485? AddressingSerial; allows multiple sensors to be connected to any RS485 or SDI-12 data logger via a single cable. Simply using the provided USB converter cable is not working for me right now with the Pi. If your application requires RS485, use the primary serial port (serial1) for RS485 communications, and use the secondary serial port (Serial 2) to program and debug your application code using the RS232 protocol. We have built sophisticated instruments using the QScreen Controller that operate very reliably using multiple interrupts in addition to the software UART. A PoE device needs to accept both variations in either polarity (4 possibilities) to be fully standards-compliant, rs485 cable in addition to the signalling that a standards-compliant source requires to enable the power on that port. The standard specifies a differential form of signalling.

I would highly discourage the use of extra signal pins in the connectors for "cable connected" checking that do not meet the same specs as the RS485 signalling signals. This allows for basic error detection, in that if noise on the transmission line causes one bit to be received incorrectly, either received as a '0' when transmitted as a '1' or vice-versa, the error would be detected due to the count of '1' bits in the byte being odd when it is expected to be even, or vice-versa depending on the parity checking settings. UART interface support for 7 or 8 data bits, 1 or 2 stop bits and odd / even / mark / space / no parity. If you need technical support or have any feedback/review, please click the Submit Now button to submit a ticket, Our support team will check and reply to you within 1 to 2 working days. To interface devices that support synchronized serial interfaces, but are not configurable like the QScreen, determine the device’s requirements for clock phase and polarity and configure the QScreen’s CPHA and CPOL accordingly.