Laurel

RS485 Modbus Interface Board for Laurel Electronics 1/8 DIN Instruments

Features
Allows up to 247 meters to be addressed using the Modbus protocol. Allows up to 31 meters to be addressed using the Laurel ASCII protocol.
Dual RJ45 connectors allow daisy chaining of meters without a hub. Suitable for all 1/8 DIN Laureate DPMs, counters, timers & remote displays.
Jumper selectable 2-wire (half duplex) or 4-wire (full duplex) operation. Selectable baud rates to 19,200.
Isolated from meter and power grounds.  
Description
The Laureate RS485 Modbus interface board allows multiple Laureate meters, counters, timers and remote displays to be connected to the same Modbus RS485 line. Dual RJ45 jacks allow multiple devices to be daisy-chained using 8-wire data cables or patch cords with RJ45 plugs.

The RS485 Modbus interface board is identical to the RS485 Interface Board, except that it uses 8-wire RJ45 jacks as recommended by the Modbus standard, as opposed to 6-wire RJ11 jacks. Both boards are equally compatible with the Modbus RTU and Modbus ASCII protocols.

Operation can be configured for full-duplex or half-duplex operation using jumpers on the RS485 Modbus board. Transmission distances up to one mile are possible. In case of long line lengths, a jumper can be plugged in the RS485 Modbus board at the end of the line to insert a 120-ohm termination resistor to minimize signal reflections.

Two serial multipoint protocols are user-selectable and are implemented on the meter main board: the Laurel ASCII protocol and the Modbus protocol. For detailed information, please see our Modbus Protocol Serial Communications Manual and Serial Communications Manual or

  • The Modbus protocol is an international standard and allows Laureates to share the same RS485 data lines with non-Laurel devices. It supports up to 247 digital addresses. Use of more than 31 Laurel RS485 Modbus boards requires repeaters for impedance reasons.
  • The Laurel ASCII protocol is the simplest and is recommended if the only devices on the RS485 data line are Laureate meters. It supports up to 31 digital addresses.

Specifications

Electrical Specifications
Ethernet Board Specifications
Connection Full duplex (RXD0, RXD1, TXD0, TXD1) or half duplex (TX / RXD0, TX / TXD1)
Data rates 300, 600, 1200, 2400, 4800, 9600, 19200 bps
No. of devices on data line Up to 31 without a repeater, 247 Modbus addresses
connector Dual RJ45 jacks for daisy chaining without a hub
Line length, max 50 to 1000 ft (15 to 300 m) depending on cable
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
Protocol Specifications (implemented on meter main board)
Modbus RTU
Standards Compliance Modbus over Serial Line Specification V1.0 (2002)
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
Applicable Interface Boards Ethernet, USB, RS232, RS485, RS485 Modbus
Conversion to Modbus TCP Automatic
Main Board Revision Level Level 5 or above
Modbus ASCII
Standards Compliance Modbus over Serial Line Specification V1.0 (2002)
Data Formats (selectable) 1. No parity, 7 data bits, 2 stop bits
2. Odd parity, 7 data bits, 1 stop bit
3. Even parity, 7 data bits, 1 stop bit
Applicable Interface Boards Ethernet, USB, RS232, RS485, Modbus RS485
Conversion to Modbus TCP Automatic
Main Board Revision Level Level 5 or above
Laurel ASCII
Data Format No parity, 8 data bits, 1 stop bit
Protocol Laurel Laurel ASCII
Applicable Interface Boards Ethernet, USB, RS232, RS485, RS485 Modbus
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.
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