Laureate USB Interface 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 /Sitemap/Logging-Meter-Counter-Readings and user manual - 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).
