Laurel Electronics LT SERIES TRANSMITTERS PULSE INPUTS - Manual (Page 4)

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3. PRODUCT OVERVIEW
This manual covers LT Series DIN rail transmitters with isolated 4-20 mA and RS232/RS485
outputs, dual relays, and a pulse input signal conditioner. A separate manual covers LTE Series DIN rail
transmitters with isolated 4-20 mA and Ethernet outputs, dual relays, and a pulse input signal
conditioner.
LT Series transmitters duplicate the signal conditioning and signal processing features of their
1/8 DIN panel-mounted counter / timer counterparts for exceptional accuracy at high read rate. A
wide range of counter / timer functions are accommodated by three signal conditioners:
• Dual-channel pulse input signal conditioner (for frequency, rate, total, arithmetic combina-
tions of two channels, stopwatch, timer, phase angle, duty cycle).
• Voltage-to-frequency signal conditioner (for rate or total from 4-20 mA, 0-1 mA or 0-10V
process signals).
• Quadrature signal conditioner (for position or rate from quadrature encoder signals).
An isolated 4-20 mA, 0-20 mA or 0-10V output is standard. This output is generated by an ultra-
linear 16-bit digital to analog converter which tracks an internal linearized digital reading.
Isolated serial communications are standard. The transmitter serial port is default jumpered for
RS232 or full-duplex RS485 (same jumper settings). Half-duplex RS485 is also selectable either
via internal or external jumpers. Three serial protocols are software selectable: Modbus RTU,
Modbus ASCII and Custom ASCII. Modbus allows devices by different manufacturers to be
addressed on the same data line. The simpler Custom ASCII protocol is recommended when there
are no devices by other manufacturers on the data line.
An isolated transducer excitation output is standard. Three output levels are jumper selectable:
5V at 100 mA, 10V at 120 mA, or 24V at 50 mA. The factory default setting is 10V and can power
up to four 350 ohm load cells in parallel.
Isolated dual solid state relays are standard. These are rated 120 mA at 140 Vac or 180 Vdc.
Isolation to 250V rms is provided for power, signal input, analog output, relay outputs, and com-
munications. Isolation adds safety and avoids possible ground loops. The transducer excitation
output is isolated to ±50V from signal ground.
Internal jumpers are used to select the signal range, communication type, and excitation level.
The transmitter configuration is specified by the model number on the transmitter label. A user
can reconfigure the transmitter by opening the case and moving jumpers.
Transmitter scaling is via serial connection to a PC using MS Windows based Instrument Setup
Software, which can be downloaded at no charge. The required transmitter-to-PC interface cable
is available for purchase.