LT-QD

Laurel 4-20 mA & Serial Data Output Transmitters for Position or Rate from Quadrature Encoders

Laurel Electronics Inc.

  • 4-20 mA, 0-20 mA, 0-10V or -10V to +10V transmitter output, 16 bits, isolated
  • RS232 or RS485 serial data output, Modbus or Laurel ASCII protocol, isolated
  • Dual 120 mA solid state relays for alarm or control, isolated
  • Accepts low-level differential or single-ended 5V logic level signals from shaft encoders, linear encoders, incremental encoders or optical encoders
  • Programmable for position, angle or rate
  • Quadrature count x1, x2 or x4 with combined pulse rate to 250 kHz
  • Zero channel input

Details

The Laureate quadrature transmitter accepts A & B quadrature encoder signals to provide an analog output that tracks position, length, angle, or rate. The A & B quadrature signals are 90° out of phase, and their phase relationship determines whether up counts (+) or down counts (-) are produced.

One, two or four quadrature transitions may be counted at a maximum combined rate of 250 kHz and be scaled internally to ±999,999 counts. The input circuitry may be jumpered for either single-ended input signals or for balanced line driver signals. Anti-jitter circuitry eliminates errors produced by vibration of the encoder. In the event of a power failure, the latest total may be stored in non-volatile memory and can be used as the starting point for counting when power resumes. Power fail or zero index capabilities are alternate meter setup choices.

A zero index pulse, if available, is interpreted as indicating a zero reference for an integral number of revolutions of a rotary shaft encoder or the home position of a linear encoder. It is used by the meter for initializing and to correct for any cumulative pulse count errors. Special circuitry corrects for width of the zero index pulse.

Available for Total or Rate

  • With the Standard main board, the transmitter totalizes the quadrature counts and then scales the total in software for the output. A zero index Z signal can be added as a third input to the A & B signals. The analog output is generated by an ultra-linear 16-bit (65,536 step) digital-to-analog converter (DAC) for 0.02% output accuracy.
  • With the Extended main board, the transmitter can be programmed to output either total or rate or rate. For example, the output can track the speed of a moving slab from the RPM of a roller. The update rate for rate is a programmed gate time + 30 ms + 0-2 pulse periods.

Standard features of Laureate LT transmitters include:

  • 4-20 mA, 0-20 mA, 0-10V or -10V to +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.
  • Serial communications output, RS232 or RS485 (half or full duplex), jumper selectable. 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 is simpler than the Modbus protocol and is recommended when all devices are Laureates.
  • Dual solid state relays, isolated, for alarm or control. Rated 120 mA at 140 Vac or 180 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.

Laureate DIN Rail Transmitter Case

Key Features:

  • Mounts to 35 mm rail per DIN EN 50022
  • 129 mm deep x 104 mm high x 22.5 mm wide
  • Rugged black polycarbonate housing material
  • Detachable screw clamp connectors meet VDE / IEC / UL / CSA standards
  • For Laureate transmitter series LT, LTE, LTS, LTSE
  • Weight of complete transmitter 183 g (6.5 oz)

Specifications

Interface
RS-232
RS-485
Input Type
Frequency
Counter
Output Type
0 - 10 V DC
±10 V DC
0 - 20 mA
4 - 20 mA
Min Temperature
0°C
Max Temperature
55°C

Models

LT-QD
4-20 mA & Serial Data Output Transmitters for Position or Rate from Quadrature Encoders

Downloads

LT-QD, 4-20 mA & Serial Data Output Transmitter for Quadrature Encoder Input
LT-QD, 4-20 mA Output Transmitter, Quadrature Input