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Panel Meters - Counters - Timers - Transmitters, 4-20 mA & Modbus - Ethernet - USB - RS485 - RS232

High-Speed Ethernet Board P/N LNET1 with USB & RS485

LNET1 Ethernet and USB communications board

Key Features

  • Fits all Laureate 1/8 DIN size instruments.
  • Allows Laureate instruments to be polled using Modbus commands.
  • Network speeds of 10 or 100 Mbits/sec.
  • Can be polled via Ethernet every 2 msec.
  • Includes Mini-USB port for programming or data transfer at 38400 baud.
  • Includes RJ11 RS485 port for programming, for operation as a Modbus slave at up to 115200 baud, or for operation as a Modbus master at 19200 baud to up 31 meters or transmitters on an RS485 bus.
Description

LNET1 is a second generation communications board that plugs into the middle slot of a Laureate host 1/8 DIN digital panel meter, counter or timer. It provides high-speed Ethernet, USB and RS485 ports to connect the host instrument to an external PC or HMI. High data rates are a major advantage compared to Laurel's first-generation LNET communication boards.

Ethernet operation complies with IEEE 802.3 and utilizes an industry-standard RJ45 jack for a 10/100 Base-T connection to a local area network (LAN) or directly to a PC or HMI. Multiple instruments, each with their own assigned IP address, can be individually addressed and polled. Data rates can be 10 or 100 Mbits/sec depending on the router. Using Ethernet and Modbus TCP, the LNET1 board can be polled every 2 msec.

A mini-USB connector is standard and can be used for meter programming or for data polling as a Modbus slave at 38400 baud in parallel with polling via Ethernet. To connect to the USB port of a PC, use our cable CBL07 or another readily available A-male to Mini-B USB cable.

An RJ11 connector is standard for RS485 and can be used for meter programming, for data polling as a Modbus slave at up to 115200 baud, or for operation as a Modbus master at 19200 baud to an RS485 bus with up to 31 adressable Laureate meters or LT series transmitters. Meters on the RS485 bus can be daisy chained using our CBL03 data cables. LT transmitters can be added using our BKBD breakout board.

Cached operation is a key feature of the LNET1 board. It allows the host meter to be polled at the maximum rate allowed by the meter's main board, and in turn to be polled asynchronously at a much faster rate using external Ethernet or USB communications and Modbus RTU/TCP commands. These are document in our LNET1 & LNET1-485 user manual. Updated analog readings can be retrieved every 18 or 21 msec, depending on the meter's 60 Hz or 50 Hz AC line noise rejection setting. Cashed counter readings can be retrieved every 10 msec.

Setup of WiFi, USB and RS485 communications uses our free Laurel Network Setup (LNS) utility. It automatically discovers the board's Ethernet IP address assigned by the WiFi router, the COM port used for USB communications, the meter type, and the signal conditioner type. The USB or RS485 ports can also be used with our free Instrument Setup (IS) software to set up the host instrument and remote instruments on an attached RS485 bus.

Networks with LNET1 Boards
Network with Ethernet meters
Network with Ethernet meters
Specifications
Ethernet Operation
Ethernet application Operation of host meter as a Modbus slave
Ethernet standard IEEE 802.3
Ethernet connector RJ45 jack
Ethernet cable 10/100 Base-T
Data rate 10 or 100 Mbits/sec
Communications protocol Modbus TCP (same commands as for Modbus RTU)
Min read interval from cache 2 msec
USB Operation
USB applications Laurel Network Setup, host meter programming, operation of host meter as a Modbus slave.
USB connector Mini-USB
USB cable Mini-USB to Type A (CBL07) or customer furnished
Data rate 38400 baud
Communications protocol Modbus RTU (same commands as for Modbus TCP)
Min read interval from cache 10 msec
COM port Discovered by Laurel Network Setup (LNS) utility
RS485 Operation
RS485 applications Laurel Network Setup in lieu of USB, host meter programming, operation of host meter as a Modbus slave, or operation as a gateway to an RS485 bus with up to 31 meters or transmitters.
RS485 connector RJ11 jack
RS485 cables CBL06 adapter cable to PC USB port, CBL03 to daisy chain meters on RS485 bus.
RS485 Data rate 1200 to 115200 baud as a Modbus slave, 19200 baud as a Modbus RS485 master
Communications protocol Modbus RTU (same commands as for Modbus TCP)
Min read interval from cache 10 msec
COM port Discovered by Laurel Network Setup (LNS) utility
Cache Memory
Data written into cache Display value or set of 6 values (user selectable)
6 values for analog in DPMs Alarm status, display value, peak, valley, display value, display value
6 values for scale meters Alarm status, display value, peak, net weight, gross weight, display value
6 values for counters Alarm status, item 1 (display value), peak, valley, item 2, item 3
Write interval for 1 value 18 msec or 21 msec (filtering set for 60 Hz or 50 Hz noise rejection)
Write interval for 6 values 108 msec or 126 msec (filtering set for 60 Hz or 50 Hz noise rejection)
Read inteval from cache Set by externa Modbus Master, 2 msec min for Ethernet, 10 msec min for USB
Measurement Update Intervals
Analog input meter 18 msec or 21 msec (filtering set for 60 Hz or 50 Hz noise rejection)
Totalized pulse readings Signal period or programmable gate time from 10 msec to 199.99 sec
Frequency/rate readings Gate time + 30 msec + 1-2 signal periods
Communication Protocols
Meter polling via Ethernet Modbus TCP (same command set as for Modbus RTU)
Meter polling via USB Modbus RTU (same command set as for Modbus TCP)
Meter programming Custom ASCII protocol for Instrument Setup (IS) software
Mechanical
Board dimensions 79 x 39 mm
Mounting location Middle slot of Laureate Series 2 panel meter or counter
Environmental
Operating temperature -40°C to 85°C
Relative humidity 95% from 0°C to 85°C, non-condensing
Electrical Protection
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 1000-4-4
Short circuit protection Continuous
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