9 Rules for Correct Cabling of the Modbus RS485 Communication Systems

Laureate meter and LT series transmitters support the Modbus RTU protocol and Laurel’s simpler ASCII character based Custom ASCII protocol. A challenge is that Laureate meters use RJ11 jacks, while Laureate LT series transmitters use screw-clamp connectors for three discrete wires. 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. By using two jacks, up to 31 L485 boards can be connected in parallel for daisy chaining using readily available CBL03 data cables with no need for a hub. 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. In order to avoid errors when many devices are connected, cables of the same colour should be used for all the connections to the terminals A and cables of the same colour should be used for all the connections to the terminals B of the various devices (e.g. white for A and blue for B).

All the ‘A’ terminals must be connected together and all the ‘B’ terminals must be connected together respectively. In this case it is possible to connect the main inlet and outlet terminal directly to the terminals of an instrument without creating a branch. If the serial port terminal device receives data but does not respond properly, monitor the data from the serial port device. Confirm hardware connections including serial port devices, and check if your gateway and energy meter are correctly connected. 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. A T- --B; Check if the instructions sent to 485 are correct; Are there proper responses from 485 after sending correct instructions? Use a 485 to USB serial cable, connect it to the interface of the 485 device and the computer's USB port, assign a COM port on the computer, open serial debugging assistant software, set the serial port parameters consistently, input the corresponding COM port, and monitor the data from the 485 device. When you scan the bar code, the information actually gets sent on a 485 transceiver through a long cable to a PC somewhere within the store.

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. It may be used to control video surveillance systems or to interconnect security control panels and devices such as access control card readers. In theatre and performance venues, RS-485 networks are used to control lighting and other systems using the DMX512 protocol. Both boards support the Modbus protocol and Laurel’s Custom ASCII protocol, as well as half-duplex or full-duplex RS485 communications. What RJ11 cables should I use with RS485? What cable should I use to connect meters with an RS485 port to the USB port of a PC? Question:Does RS485 TO ETH support Modbus transmission? 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. If you're sitting in the office right now, and you look to see your thermostat, there's usually RS-485 transceivers connecting that from there to basically the control unit in the building.

It is also used in Digital Command Control (DCC) for model railways. If you change boards, also change the model number on the meter label. The maximum number of repeaters that should be serially connected is 3. A higher number introduces excessive delays in the communication system. Using a repeater, the main cable is divided into different segments, each of which can be up to 700 m in length and connect 32 devices (this number includes the repeaters). Can the device IP be pinged (by default)? On the other side we also have converter RS232 - RS485 ATC - 108N, via the RS232 port is connected to cash or other device with RS232 port. Confirm serial port parameters such as baud rate, data bits, and stop bits: Baud rate should be configured according to the connected RS485 device, commonly used rates are 9600 and 115200; Refer to the device manual or contact RS485 device technical support for configuration, especially if set to Modbus mode, confirm if the function code matches. First set jumpers for your type of communications. The presence of a new board and the type of board are automatically sensed by the meter’s firmware or by Instrument Setup (IS) software.

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