Laurel Electronics LT: 4-20 mA & Serial Data Output Transmitter for Duty Cycle Input - 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 Duty Cycle Input
Features
• Transmits ON or OFF period as a percentage of total period
• Frequencies from 0.005 Hz to 10 kHz
• Inputs from NPN or PNP proximity switches, contact closures, digital logic,
magnetic pickups down to 12 mV, or AC inputs up to 250 Vac.
• 4-20 mA or 0-10V transmitter output, jumper selectable, isolated
• Analog output resolution 0.0015% of span (16 bits), accuracy ±0.02% of span
• RS232 or RS485 serial data output, half or full duplex, isolated
• Modbus RTU, Modbus ASCII or Laurel ASCII protocol
• 5V, 10V or 24V dc transducer excitation output, isolated
• Dual solid state relays 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 duty cycle transmitter tracks ON or OFF period
as a percentage from 0% to 100% of total period of repetitive
pulse trains. In the illustration, duty cycle is 100 x t/P. The trans-
mitter determines duty cycle by averaging an integral number of
periods over a gate time, which is selectable from 10 ms to
199.99 s. The same signal is applied to Channels A and B. The
unit divides the average pulse width by the period between
pulses and expresses this ratio in percent. A resolution of 1%,
0.1% or 0.01% is selectable. By selecting leading or falling pulse
edges, the ON or OFF duty cycle can be transmitted.
The dual-channel signal conditioner used for pulse detection
accepts inputs from proximity switches with PNP or NPN output,
TTL or CMOS logic, magnetic pickups, contact closures, and AC
signals from 12 mV to 250 Vac. Jumper selections provide opti-
mum operation for different sensor types and noise conditions.
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).
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 500 ohm (or lower) load for
10V compliance, or 10V into a 5K ohm (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.