Ethernet & 4-20 mA Output Transmitter for Process & Ratiometric Signals

The Laureate 4-20 mA output, process signal input transmitter provides zero and span adjustment for use with a wide range of industrial transducers. Six DC voltage and four DC current input ranges are jumper selectable. The two most sensitive voltage ranges, 200.00 mV and 2.0000V, provide a high input impedance of 1 GΩ to minimize the load on the voltage signal.

The transmitter can be set to a ratio (or potentiometer follower) mode by making selections at the connector and in software. In this mode, the transmitter output tracks a ratio of the applied excitation voltage and is unaffected by changes in the excitation voltage. Ratiometric measurements provide an exceptional accuracy of 0.01% of reading ± 2 counts. This capability is used with the meter's 5V or 10V excitation output for load cells and Wheatstone bridges, and with the meter's 5V excitation output for potentiometers which track wiper position.

Fast read rate at up to 50 or 60 conversions per second while integrating the signal over a full power line cycle is provided by Concurrent Slope (Pat 5,262,780) analog-to-digital conversion. High read rate is ideal for peak or valley capture and for real-time computer interface and control. Digital signal filtering modes are selectable for stable readings in electrically noisy environments. The internal digital readings and analog output can be individually selected to be either unfiltered or filtered.

Standard features of Laureate LTE transmitters include:

• Ethernet I/O, isolated. The supported protocols are Modbus RTU and ASCII, which are tunneled via Modbus TCP. Note that RS232 or RS485 data I/O is provided by Laurel's LT Series transmitters.
• 4-20 mA, 0-20 mA or 0-10V analog transmitter output, isolated, jumper-selectable and user scalable. All selections provide 16-bit (0.0015%) resolution of output span and 0.02% output accuracy of a reading from -99,999 to +99,999 counts that is also transmitted digitally. Output isolation from signal and power grounds eliminates potential ground loop problems. The supply can drive 20 mA into a 500 ohm (or lower) load for 10V compliance, or 10V into a 5K ohm (or higher) load for 2 mA compliance.
• Dual solid state relays, isolated. Available for local alarm or control. Rated 120 mA at 130 Vac or 180 Vdc.
• Universal 85-264 Vac power. Low-voltage 10-48 Vdc or 12-32 Vac power is optional.

Node discovery and configuration of Laureate Ethernet transmitters are easily achieved with Laurel's Windows based Instrument Setup Software. Additional features are provided by Laurel's Windows based Node Manager Software, such as the ability to send emails or test messages either periodically or in the event of an alarm. Both softwares run on a PC under MS Windows, are at no charge, and can be downloaded from this website.

Custom curve linearization

A Laureate process meter or transmitter with the Extended main board option allows exceptionally accurate custom curve linearization. For setup, up to 180 data points can be entered into a spreadsheet. The system then creates multiple non-linear spline-fit segments, which provide much better accuracy than linear segments. One application, as illustrated, is the readout of volume of irregularly shaped tanks based on measured liquid level or pressure. Altimeters and thermistors are further applications.