Laurel Electronics LT: 4-20 mA & Serial Data Output Transmitter for Position or Rate from Quadrature Encoders - 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
Position or Rate from Quadrature Encoders
Features
• 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
• 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
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 which 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 current 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 by the meter 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 pro-
grammed 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.
Three analog output settings are jumper selectable: 4-20 mA,
0-20 mA or 0-10V. The output tracks the reading up to 999,999
counts that would be 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.
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 500Ω (or lower) load for
10V compliance, or 10V into a 5 kΩ (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.
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).