Laurel Electronics LT: 4-20 mA & Serial Data Output Transmitter for Load Cell & Microvolt Signals - Manual

LAUREL ELECTRONICS INC. , 3183-G Airway Ave., Costa Mesa, CA 92626, USA • Tel 714-434-6131 • www.laurels.com 1
LAUREL
ELECTRONICS, INC.
4-20 mA & Serial Data Output Transmitter
for Load Cell & Microvolt Signals
Features
• 20, 50, 100, 250 and 500 mV full-scale input ranges
• 4 or 6-wire hookup to avoid power supply and lead resistance effects
• Digital span adjust from 0 to ±99,999, zero adjust from -99,999 to +99,999
• RS232 or RS485 serial data output, half or full duplex, isolated
• Modbus RTU, Modbus ASCII or Laurel ASCII protocol
• 4-20 mA or 0-10V transmitter output, jumper selectable, isolated
• Easy setup using PC-based Instrument Setup Software
• DIN rail mount housing only 22.5 mm wide
• Detachable screw clamp connectors
• 5V, 10V or 24V dc transducer excitation output, isolated
• Dual solid state relay for alarm or control, isolated
• Universal AC power, 85-264 Vac, or low voltage power, 10-48 Vdc or 12-32 Vac
• Custom curve linearization and rate from successive readings (optional)
Description
The Laureate load cell or microvolt input transmitter is
designed for use with load cells, strain gauges and microvolt
input signals where exceptional sensitivity and stability are
required. A most sensitive full-scale input range ±20 mV can be
scaled internally to ±99,999 counts. The selected input range for
the full 0-20 mA output span can be as wide as ±99,999 counts
or as narrow as 150 counts, limited only by considerations of
electrical noise and time constants of the programmable moving
average digital filter.
A built-in, isolated, 10V, 120 mA excitation supply can power
up to four 350-ohm load cells in parallel. Load cell connection
can be via 4 or 6 wires. With 4-wire load connection, the
transmitter operates in a ratiometric mode to eliminate errors due
to power supply variations. With 6-wire load connection, it also
compensates for lead resistance, allowing long cable runs.
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.
• An unfiltered selection provides true peak and valley
readings and aids in control applications.
• A batch average filter selection averages each 16
conversions for an update every 1/4 sec.
• An adaptive moving average filter selection provides a
choice of 8 time constants from 80 ms to 9.6 s. When a
significant change in signal level occurs, the filter adapts by
briefly switching to the shortest time to follow the change, then
reverts back to its selected time constant. An Auto setting
selects the time constant selection based on signal noise.
Standard features of Laureate transmitters include:
• 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 500Ω (or lower) load for
10V compliance, or 10V into a 5kΩm (or higher) load for 2 mA
compliance.
• Serial communications output, isolated. User selectable
RS232 or RS485, half or full duplex. Three protocols are user
selectable: Modbus RTU, Modbus ASCII, or Laurel ASCII.
Modbus operation is fully compliant with Modbus Over Serial
Line Specification V1.0 (2002). The Laurel ASCII protocol
allows up to 31 Laureate devices to be addressed on the
same RS485 data line. It is simpler than the Modbus protocol
and is recommended when all devices are Laureates.
• Dual solid state relays, isolated. Available for local alarm or
control. Rated 120 mA at 130 Vac or 170 Vdc.
• Transducer excitation output, isolated. User selectable
5V@100 mA, 10V@120 mA or 24V@50 mA.
• Universal 85-264 Vac power. Low-voltage 10-48 Vdc or
12-32 Vac power is optional.
Easy Transmitter programming is via Laurel's Instrument
Setup Software, which runs on a PC under MS Windows. This
software can be downloaded from this website at no charge. The
required transmitter-to-PC interface cable is available from Laurel
(P/N CBL04).