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RS485 is simpler because it uses only two wire (or a single pair) to carry out the data in bidirectional manner, using RS232, we need 3 wires at minimum to carry the data bidirectionally. In theatre and performance venues, rs485 cable RS-485 networks are used to control lighting and other systems using the DMX512 protocol. A meter will a thermocouple input and set for Modbus RTU needs to set to full duplex even if the wiring and the receiving unit are for half duplex. RS-485 is also used in building automation as the simple bus wiring and long cable length is ideal for joining remote devices. RS-485 is used as the physical layer underlying many standard and proprietary automation protocols used to implement industrial control systems, including the most common versions of Modbus and Profibus. Some of these converters can convert from RS232 to both RS485 and RS422 however many standard models only has one of the protocols. Due to loading limitations one of the best uses of a RS232 to RS422 serial converter might be in point-to-point communications, such as extending an existing RS232 line.

Below you will see a cabling example for one master and two slaves in a full-duplex and a half-duplex situation. Henceforth, we shall consider Slave devices to be measuring instruments with serial communication, even if the cabling is similar for all Modbus devices. If the PC is connected to the multiple Laureate instruments on an RS485 bus via an Ethernet-to-RS-485 gateway board or a USB-to-RS485 gateway board, use Laurel’s free XLOG2 datalogging software. These cables allow the dual RJ11 jacks of the RS485 option board of Laureate meters (digital interface ordering option 2) to be daisy chained and to be addressed digitally with no need for a hub. Both will work with RJ11 connectors and CBL03 cables. The board with dual RJ11 jacks is the more popular since is can use commercial straight-through, non-reversing, 6-wire data cables with RJ11 connectors. Laureate RS485 boards are available in versions with dual RJ11 jacks (ordering option 2, board P/N L485) and with dual RJ485 jacks (ordering option 4, board P/N LMOD). What are setup steps for RS485? The advantage of the RS485 protocol is that this it can transfer data over longer distances, up to 4000 feet, and have up to 32 nodes per single network, and it can be used for multi-point networks where multiple serial devices are setup in a bus network.

In order to increase the extent of the Modbus network, repeaters can be used; and signal amplifying and regenerating devices provided with two communication ports that transfer to each what they receive from the other. So in order to transfer data from a RS232 serial interface engineers need a converter to be able to connect to a RS485 or RS422 interface. Why use a RS232 - RS485 /RS422 converter? 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. Connect the Master Brick via USB, Ethernet or WIFI with your PC and start the Brick Viewer software. Even better is Ethernet cable, because it is twisted and often shielded. Interoperability of even similar devices from different manufacturers is not assured by compliance with the signal levels alone. 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. Note that these cables are different from4-wire telephone cables or crossover cables.

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. What RJ11 cables should I use with RS485? If you restart the RS485 Master, every Brick/Bricklet of the RS485 network will send the initial enumeration message again. If you restart the RS485 Slave, only the Bricks/Bricklets that are connected to this stack will send the initial enumeration message again. The shielding may be braided (be formed by a mesh of thin conducting wires) or be a foil (consisting of a sheet of metal wound around the conductors): the two types are equivalent. A slave device may only speak when it is spoken to. This means that the master has to grand the slave permission to send. For master configuration choose "Master" as type and input the addresses of the slaves in the RS485 bus as a comma separated list. 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. The RS485 Extension can be positioned in the stack as you wish.