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The Laureate USB-to-RS485 Gateway Board P/N LNET485 can connect a computer with a USB port to a Laureate host meter or counter and to up to 31 Laureate remote meters and counters on an RS485 bus. It features a USB Type-B connector for connection to a PC via a standard USB cable (Laurel cable CBL05), plus an RJ11 jack for interface to an RS485 bus with up to 31 Laurel meters equipped with Laurel's RS485 interface board. That board provides dual RJ11 connectors wired in parallel for RS485 daisy-chaining using commercial 6-wire RJ11 data cables (Laurel cable CBL03), with no need for a hub.
Two serial protocols are user-selectable: Modbus RTU and Custom ASCII. The text string based Laurel ASCII protocol is the simplest and is recommended if Laureates are the only devices on the network. For more information, please see our Modbus Protocol Serial Communications Manual and our Serial Communications Manual. The Laurel Laurel ASCII protocol supports 31 device addresses, one of which needs to be the converter board. The two Modbus protocols support 247 device addresses; however, only 31 addresses can be electrically driven on an RS485 line without a repeater.
Multiple meters on an RS485 bus can also be digitally addressed using our Ethernet-to-RS485 converter board, which can be connected directly to a PC via an Ethernet cable or via the Local Area Network (LAN) to with the PCis also connected.
Connecting the LUSB485 board to a PC will cause the PC to download the required driver. The board is connected to PC via a UART, so you need to specify RS485 communications. Specify the baud rate, normally 9600, and enter the COM port number assigned by the computer. The individual meters, including the host meter, are selected in software by their own digital address, which can be entered from the meter front panel or by using Laurel's free Windows-based Instrument Setup Software.
 USB & RJ11 connectors |
 USB cable, P/N CBL05 |
| RS485-to-RS485 Converter Board P/N LNET485 | |
|---|---|
| Baud Rates | 300, 600, 1200, 2400, 4800, 9600 |
| Devices per PC USB Port | 1 for host meter plus up to 31 on RS485 bus |
| USB Connector | USB Type-B receptable |
| USB Compliance | Universal Serial Bus Spec Revision 2.0 |
| USB Line Length, Max | 5 m |
| Devices per RS485 Line | Up to 31 |
| RS485 Connector | RJ11 jack |
| RS485 Compliance | EIA/TIA-485 |
| Power to Converter Board | Via USB line |
| Isolation | 250V rms working, 2.3 kV rms per 1 min test |
| ESD Protection | 15 kV per IEC 1000-4-2 |
| EMI Immunity | 10 V/m per IEC 1000-4-3 |
| EFT Protection | 2 kV per IEC 1000-4-4s |
| Short Circuit Protection | Continuous |
| Selectable Protocols | Modbus RTU, Custom ASCII. |
| Modbus RTU Protocol | |
|---|---|
| Standards Compliance | Modbus over Serial Line Specification V1.0 (2002) |
| Protocol Type | Master-slave, query-response command mode |
| Data Streaming Mode | Not supported by Modbus specification |
| Data Formats (selectable) | 1. No parity, 8 data bits, 2 stop bits |
| 2. Odd parity, 8 data bits, 1 stop bit | |
| 3. Even parity, 8 data bits, 1 stop bit | |
| Main Board Revision Level | Level 5 or above |
| Custom ASCII Protocol | |
| Standards Compliance | Laurel proprietary protocol |
| Data Format | No parity, 8 data bits, 1 stop bit |
| Protocol Type | Text string based command mode or continuous data streaming mode |
| Data Streaming Mode | User selectable for up to 60 readings/sec |
| Main Board Revision Level | Any |
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