Ethernet & 4-20 mA Output Transmitter for Bidirectional Position or Rate from Quadrature Encoders

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.

Bidirectional 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.

Unidirectional Total and Rate

If the counts are only for one direction, for example for extusions measured by an encoder wheel, only the encoder's "A" channel can be used and be output to an Extended Laureate totalizer transmitter. This model accommodates very high pulse rates up to 1 MHz, and unlike the quadrature transmitter, it can simultaneously track rate and total.

Standard features of Laureate LTE transmitters include:

• Ethernet I/O, isolated. The supported protocols are Modbus RTU and ASCII, which are tunneled via Modbus TCP. Note that RS232 or RS485 data I/O is provided by Laurel's LT Series transmitters.
• 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.
• Dual solid state relays, isolated. Available for local alarm or control. Rated 120 mA at 130 Vac or 180 Vdc.
• Universal 85-264 Vac power. Low-voltage 10-48 Vdc or 12-32 Vac power is optional.

Node discovery and configuration of Laureate Ethernet transmitters are easily achieved with Laurel's Windows based Instrument Setup Software. Additional features are provided by Laurel's Windows based Node Manager Software, such as the ability to send emails or test messages either periodically or in the event of an alarm. Both softwares run on a PC under MS Windows, are at no charge, and can be downloaded from this website.