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Test options include: audio, video, ping, TDR, PoE, IP network connections, and LAN (local area network) cable connections. Display and configure video; control PTZ; test cables, audio, IP network connections, PoE voltage; and power 12VDC cameras. The TESTER-CCTVPOE-P Professional CCTV Tester with Power Over Ethernet (PoE) and IP Testing is a portable, multifunction tester for CCTV installations and maintenance. Digital communications networks implementing the standard can be used effectively over long distances and in electrically noisy environments. This provides high noise immunity and allows distances up to 4,000 ft (1200 meters). A symmetrical pin-layout allows two DTEs, data terminal equipment, to be connected directly without use of a modem or other DCE, data communication equipment. RS-485 does not define a communication protocol; merely an electrical interface. The RS485 converter interface uses two wires for communication, one for transmitting and one for receiving data, which is referred to as a half-duplex communication converter.

RS485 is a balanced serial interface for the transmission of digital data. The serial RS232 to RS485 converter and RS232 to RS422 converter units, also called serial converters, are small electronic devices used to convert a serial RS232 signal, (for example the COM port in older computers) into either RS485 or RS422 signals. These signals are commonly called A and B in RS485 systems. I am beginning to suspect that the board is not writing to the RS485 adapter correctly, or that pins are not mapped correctly. The Master Brick of each stack has to be the lowermost Brick (except if you are using a Power Supply). All the other Master Bricks with RS485 Extension must not have a USB, Ethernet or WIFI connection (they can use a USB Power Supply). RS485 cable length can be as long as 1.2 km, while RS232 only about 25 meters. Use Laurel’s 6-wire data cables CBL03-1 (1 ft) and CBL03-7 (7 ft) to interconnect meters if these lengths fit your application. The data is coded as a differential voltage between the wires. At the receiver end the voltage difference should not be less than 0.2 Vdc.

Extending a RS232 line is done by converting the RS232 signal into RS422 and then back to RS232 at the remote end. If the bus is only a few meters long then the cable you use should not matter. If the bus is longer than a few meters then some kind of twisted pair cable is recommended. We then added the 10K pull-up and pull-down resistors to the RS485 Pi board and connected it directly to the Solis inverter. You should see the Master Brick view with the identified RS485 Extension (see images below). The Master Brick has to be restarted to apply the new configuration. At the end, press "Save RS485 Configuration" to save the configuration permanently on the RS485 Extension. Most newer consumer electronics comes with an USB, Firewire or other high-speed communication port, however a lot of industrial and commercial equipment, both old and new, is made only with a RS485 or RS422 serial communications port. The connection between the board and the PC is done through the ultra mini serial to DB9 cable and I can successfully read/write data from and to the board.

A RS232 - RS485 converter is often used in industrial data acquisition and control applications where multiple serial devices communicate with each other through a converter. For example you need to consider the noise level in the environment surrounding the serial converter. The typical serial converter does this in both directions which is also referred to as a bi-directional converter. The reason is that the serial RS232 protocol is, even its old, a very reliable, stable and solid communication protocol, which can easily be implemented with existing industrial equipment. Even better is Ethernet cable, because it is twisted and often shielded. Even RS485 is not commonly as popular as RS232 it is extremely useful for converters in industrial and commercial environments. Usually a RS232 - RS485 converter is the preferred way to establish multi-point networks when working with RS232 devices. The RS422 converter is used for data transmission, using balanced or differential signaling, it is mainly used in industrial and commercial environments since lots of process equipment and machinery have this protocol built-in. RS485, also known as TIA/EIA-485 is a standard serial communications protocol defining the electrical characteristics of a serial converter, drivers and receivers for use in balanced RS485 digital multipoint systems.