LAUREL LTS, Owner'S Manual

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3. INTRODUCTION, RS232 OR RS485 SERIAL INPUT TRANSMITTER
The LTS serial input to analog output transmitter (or serial-to-analog converter) accepts
numeric readings embedded in streaming RS232 or RS485 ASCII serial data, and converts
these to an isolated, scalable 4-20 mA, 0-20 mA, 0-10V or -10V to +10V analog output. It also
accepts Modbus RTU or Custom ASCII protocol commands to output a specific current or
voltage. The unit fits on a 35 mm DIN rail and is only 22.5 mm (0.89") thick. Model LTS60 can
be powered by 85-264 Vac AC line voltage. Model LTS61 can be powered by low voltage AC or
DC, like 24 Vdc. All electrical connections are via detachable screw-clamp plugs. LTS models
use an LT counter transmitter board, but no signal conditioner board. LT counters with a signal
conditioner board, like model LT60FR, can also be used for serial to analog conversion.
The current or voltage transmitter output
is jumper selectable and is transformer isolated to
avoid ground loops. Either output provides 16-bit resolution of the output span and is ultra-
linear to within one bit. The output is scaled to the serial input in software. Rated accuracy is
±0.02% of span.
Dual solid state relays rated 120 mA at 140 Vac or 180 Vdc are standard. The relays can
respond to the transmitted serial values or to transmitted control characters, which override the
internal setpoints. The relays can also be controlled independently of the serial input by
applying signals to control inputs 1 and 2.
Isolation to 250V rms is provided for power, the serial data input, analog output, and relay
outputs. Isolation adds safety and avoids possible ground loops.
Serial data input selections are RS232, half-duplex RS485, or full-duplex RS485. Selection is
via jumpers and/or at the connector.
Transmitter setup is via the unit’s serial port using an external PC and Instrument Setup
software, which can be downloaded from our website at no charge. The required 3-wire
transmitter-to-PC interface RS232 cable (CBL04) is easy to build and is also available for
purchase. Plugging cable CBL04 into a CBL02 RS232-to-USB converter cable allows the LTS
unit to be programmed via the USB port of a PC.
The LTS is not plug and play. The format of the strings being received must be known in
advance, including non-printing control characters. If you do not know the format of your ASCII
data, contact tech support of the manufacturer of the sending device. Or use a terminal
emulator PC program, like
HyperTerminal , PuTTY , or RealTerm , to view the received data on
your PC.
The LTSE6 Ethernet input to analog output transmitter accepts streaming Ethernet data and
converts it to an isolated, scalable 4-20 mA, 0-20 mA, 0-10V or -10V to +10V analog output.
That transmitter is covered by a separate user manual.