Features
- Suitable for all 1/8 DIN Laureate DPMs, counters, timers & remote displays
- Connects host meter to a computer via USB 2.0 and to a bus with up to 31 Laureate instruments
- Includes USB Type-B connector to PC plus RJ11 jack to RS485 bus
- Selectable baud rates to 9600
- Powered by USB line
- Isolated from meter and power grounds
Certificates of Compliance
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.
Installation
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.
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| USB & RJ11 connectors | USB cable, P/N CBL05 |
Electrical Specifications
| 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. |
Protocol Specifications (protocols reside on Main Board)
| 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 |
Laurel Software Requiring a Communications Board
- Instrument Setup Software runs on a PC and provides a Windows Graphical User Interface (GUI) as an alternative to programming the meter from the front panel. This software can be downloaded from this website at no charge. Its use requires a serial communications board in the meter, but following setup that board can be removed if desired. Compatible with Modbus or Laurel ASCII protocol.
- Custom Curve Linearizing Software is compatible with the Extended option version of all Laureates. Not applicable to temperature. Custom curve linearization can provide exceptional accuracy from low cost transducers and extend their working range on the high and low ends. This software can be downloaded from this website at no charge. Meter setup requires a serial communications board in the meter and the Laurel ASCII protocol, but following setup that board can be removed if desired and any protocol can be used.
- Data Logging Software turns a PC into a data logging system. The RS232 board allows data logging with a single meter. Use of RS485 boards allows data logging with up to 31 Laureate instruments. Data can be logged from selected meters into an ASCII file, which can then be imported into MS Excel. Data can also be displayed on the computer screen in the form of up to 64 actual or virtual panel meters in 4 groups (or screens) of up to 16 meters each. Compatible with Laurel ASCII protocol only.
Laureate USB to RS485 Gateway Board Frequently Asked Technical Questions
USB is an easy-to-use interface for communications between a Laureate meter or counter with a PC. It is typically use for datalogging and for use of Laurel’s Windows-based Instrument Setup (IS) software, which runs on a PC.
USB is easier than RS232 to interface to modern PCs, since these have multiple USB ports but no RS232 port. A Laureate meter with a USB board can be interfaced to a PC using a readily available commercial USB cable, while a Laureate meter with an RS232 board requires the combination of two special cables. Please see our cables web page for details. However, do use RS232 if that is required for interface to other system components, not just to a PC.
Yes, a USB board (P/N LUSB) can simply be plugged into the middle backplane slot without any soldering. Its presence is automatically sensed by the meter’s computer board, which enables USB communications it and brings up the appropriate setup menu items.
You can easily do so. One reason to transfer a USB board from meter to meter is to program multiple meters in the same way using Laurel’s Instrument Setup (IS) software. That software runs on a PC and requires a communications board in the meter. Program a first meter manually, save its setup file on disk of a PC using IS software, and then download that setup file into multiple other meters or back into the same meter when needed.
Use a common USB cable with a square USB Type A connector on the meter end and a flat USB type B connector on the PC end. Laurel sells a 1.8 meter (6 foot) version of this cable as CBL05.
The USB interface is easy to use but is not plug-and-play. It contains an FTDI chip which converts the USB signal to a serial data signal. To set up communications with a PC, you need to specify the Com port and baud rate as fir RS232. Use Device Manager under Control Panel to find the Com port associated with the FTDI chip. Set the baud rate to 9600. Windows recognizes the FTDI converter chip and automatically brings up the required driver for it.
Laureate USB communications, along with Laureate RS232 and RS485 communications, support Laurel’s Custom ASCII protocol and the Modbus RTU protocol. The Custom ASCII protocol includes a command mode and a streaming data mode, where meter data can be output at up to 60 readings per second. The Modbus RTU protocol works in a query-response command mode only.
The easiest way to log data onto a PC via USB is to use Laurel’s free XLOG2 datalogging software, which is described in our web page at https://www.laurels.com/datalogging-software.php and user manual at https://www.laurels.com/downloadfiles/datalogging-manual.pdf. That software is limited to about 2 readings/second. To log time-stamped analog data with millisecond resolution to a PC at rates up to 60 readings/second, use a terminal emulator program like KiTTY
While the USB 2.0 specification is up to 480 Mbps, the recommended error-free USB data rate for Laureate meters and counters is 9600 baud. With analog input meters and transmitters, readings can be transmitted at the maximum analog-to-digital conversion rate of 60/second.
The USB 2.0 specification limits the length of a cable between USB 2.0 devices to 5 meters (16.4 feet). If you need serial communications over longer distances, use RS232 for up to 15 meters (about 50 feet) or RS485 for up to 1200 meters (about 4000 feet).
