Serial Communication Options
for Laureate 1/8 DIN Instruments

Description

A serial communication option board allows a Laureate digital panel meter, scale meter, counter or timer to be interfaced to a PC for programming via Laurel's free Windows-based Instrument Setup Software, or to output readings to a remote PC, PLC or other device with a serial communication port. The transmitted data may include the latest reading, peak value, valley value, alarm status, and setup information. The data can then be displayed, processed and data logged. The data can also be received by a Laureate 6-digit remote display, which will display the serial data like a meter and can also process the serial data to control relays and generate a scaled, isolated 4-20 mA or 0-10V analog output.

An RS232 board or a USB board is recommended, depending on the available PC interface, if the primary objective is to program the instrument via Instrument Setup Software. An RS485 board, Modbus RS485 board or USB-to-RS485 converter board is recommended if the objective is to communicate over long distances in an electrically noisy plant environment and to digitally address multiple instruments on the same data line. All Laureate serial inputs and outputs are isolated.

Two serial multipoint protocols are selectable. The industry-standard Modbus protocol is recommended if the Laureate instrument has to share the same data line with other Modbus devices. The simpler Laurel ASCII protocol is recommended if all devices on the data line are Laureates. For detailed information on protocols, please see our Serial Communications Manual or Modbus Protocol Serial Communications Manual.

1.  RS232 Interface Board

The Laureate RS232 board features a 6-pin RJ11 jack and is intended for point-to-point communications with a computer, PLC or other device with an RS232 port. Normally there is only one Laureate per RS232 line; however, two 6-digit Laureate remote displays can be connected to a single RS232 line in multidrop fashion and be digitally addressed.

Point-to-point communications via RS232	RS232 pinout

CBL01 cable assembly. Includes DB9 and RJ11 connectors to connect a Laureate with an RS232 board a PC com port.	Combined CBL01 and CBL02 cable assembly. Includes USB and RJ11 connectors to connect a Laureate with an RS232 board to a PC USB port.

Plugging into the Laureate is the RJ11 connector of a common 6-wire telephone extension cable. Plugging into the COM port of a PC is custom-wired DB9 to RJ11 adapter, which accepts the other end of the telephone extension cable. The DB9-to-RJ11 cable assembly is sold by Laurel as Part No. CBL01. Laurel also sells a USB-to-DB9 adapter a Part No. CBL02. A combined CBL01 and CBL02 cable assembly allows a Laureate with an RS232 interface to be connected to the USB port of a PC.

The RS232 request-to-send line (RTS) can be set to a latched mode, where a single reading is transmitted when the line is taken high momentarily. This mode allows a single data transfer to be commanded by another device.

2.  RS485 Interface Board

The Laureate RS485 board allows multiple Laureates plus non-Laureate devices to be connected to the same RS485 line in parallel, multidrop fashion. The board provides for up to 31 digital addresses, so that multiple Laureates can be addressed and transmit readings on the same data line. The use of RS485 lines optimizes utilization of computer ports and simplifies plant wiring. In the absence of a computer, a single Laureate device with an RS485 board can drive multiple Laureate 6-digit remote displays.

Transmission distances up to one mile are possible. In case of long line lengths, the RS485 board at the end of the line can be terminated by a jumper-selectable 120-ohm resistor to minimize signal reflections. A full duplex mode with separate wire pairs for transmit and receive is selectable, as is a half duplex mode with shared transmit and receive wires. For details, please see our Serial Communications Manual.

RS485 multidrop communications	RS485 pinout

The Laureate RS485 board provides two 6-pin RJ11 jacks, whose pins are wired in parallel. This allows multiple Laureates to be daisy-chained with no need for an RS485 hub.

The signal levels of the Laureate RS485 board are compliant with the EIA/TIA-485 standard. Devices by different manufacturers can share the same RS485 data line, provided that their connectors are wired appropriately. The Laureate RS485 board can be used with Modbus; however, it uses RJ11 jacks.

3.  Modbus RS485 Interface Board

The Laureate Modbus RS485 board offers all capabilities of the RS485 board and is fully compliant with the Modbus over Serial Line Specification V1.0 (2002). This includes RJ45 connectors and half or full-duplex operation (jumper selectable).

With Modbus, up to 32 devices by different manufacturers can share the same RS485 data line, be connected using similarly-wired RJ45 connectors, and be addressed using the same protocol. The Modbus Serial Line protocol is a master-slave protocol, where a master node (computer) issues commands to slave nodes (peripheral devices) on the bus and processes responses.

The Laureate Modbus RS485 board features two 8-pin RJ45 jacks wired in parallel, one of which is equipped with two indicator LEDs. The Modbus protocol is implemented by the microcomputer in the Laureate main board and is compliant with both Modbus RTU and ASCII transmission modes.

4.  USB 2.0 Interface Board

The Laureate USB 2.0 board provides a USB Type-B connector for plug-and-play connection to the USB port of a PC. It is intended for use with a PC to program a Laureate meter using Instrument Setup Software. The required USB cable is readily available in computer stores and also from Laurel as P/N CBL05.

USB Type-B connector	USB cable, P/N CBL05

The Laureate USB 2.0 to RS485 converter board includes a USB Type-B receptacle for connection to a PC, plus an RJ11 connector for interface to a multipoint RS485 network. The USB port allows meter setup with Instrument Setup Software and also serves as the PC interface to the RS485 network. In this application, the converter board is used as both a meter interface to a PC and as a USB-to-RS485 converter. The RS485 network can use the Modbus protocol or simpler Laurel ASCII protocol. Three-way isolation is provided: board to PC, board to RS485 network, and USB to RS485.

USB-to-RS485 Converter Board Specifications

Data ports
Data rates
No. of devices on USB line
No. of devises on RS485 line
No. of RS485 digital addresses
Connectors
Line length, max
Standards Compliance, USB
Standards Compliance, RS485
Three-way isolation

USB 2.0 and RS485, full duplex or half duplex.
300, 600, 1200, 2400, 4800, 9600, 19200 bps
1 per line
32 max
247 max
USB Type-B connector & RJ11 connector
5 m for USB, 4000 ft (1.2 km) for RS485
Universal Serial Bus Spec Revision 2.0, Full Speed
EIA/TIA-485
250V rms working, 2.3 kV rms per 1 min test

• Instrument Setup Software for easy meter programming using a Windows Graphical User Interface (GUI).
   
• Setup & Calibration Software can facilitate the setup of Laureate digital panel meters, scale meters, counters, timers and remote displays as an alternative to programming these devices from the front panel. It is required to set up Laureate transmitters, which don't have a front panel. It can be downloaded from this website at no charge. It utilizes Laurel's Laurel ASCII Protocol. It's use requires an external PC and a serial communications board in the meter. Following setup, this board can be removed if desired.
    
• Custom Curve Linearizing Software is applicable to the Extended option version of all Laureate digital panel meters, counters and timers, excluding only temperature meters (the latter already include preset linearization). Custom curve linearization can provide exceptional accuracy from low cost transducers and extend their working range on the high and low ends. It can also solve special application problems where there is a non-linear relationship between the input and desired readout. This software can be downloaded from this website at no charge. It utilizes Laurel's Custom ASCII Protocol. Its use requires an external PC and a serial communication board. Following setup, this board can be removed from the Laureate.
    
• Data Logging Software can turn a PC into a powerful, low-cost data logging system when connected up to 31 Laureate instruments. These can be any mix of digital panel meters, counters and timers. Data can 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. Data can be logged from selected meters into an ASCII file, which can then be easily imported into MS Excel for graphing and analysis. The logging time interval is user selectable. Requirements include an external PC with a free COM port, and RS232 to RS485 converter for multiple instruments, and a serial communications board in the meter. A modest software license fee applies. Laurel's Data Logging software works with Laurels Laurel ASCII Protocol, not with the Modbus Protocol.