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

Transmits accurate position or rate from shaft encoders & linear encoders. DIN Rail mounted, digitally programmable.

Quadrature Transmitter with 4-20 mA and Modbus Output

Features

  • 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 TDM 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
  • Analog output resolution 0.0015% of span (16 bits), accuracy ±0.02% of span
  • 5V, 10V or 24V dc transducer excitation output, isolated
  • Universal 85-264 Vac / 90-300 Vdc or 10-48 Vdc / 12-32 Vac power
Description

The 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.

Signal Conditioner Board for  Analog Input Flow Rate Meter and Analog Flow Totalizer

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 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 TDM ASCII. Modbus operation is fully compliant with Modbus Over Serial Line Specification V1.0 (2002). The TDM ASCII protocol is simpler than the Modbus protocol and is recommended when all devices are s.
  • 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.

Easy Transmitter programming is via TDM'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 TDM (P/N CBL04).

Specifications
4-20 mA & RS232/RS485 Data Transmitters for Position or Rate from Quadrature Encoders
Quadrature Inputs
Type Differential or single-ended quadrature
Transitions Monitored x1, x2 or x4
Max Pulse Rate 250 kHz at x1, 125 kHz at x2, 62.5 kHz at x4
Internal Counts -999999 to +999999
Position Error No error contributed by transmitter
Differential High Threshold +200 mV
Differential Low Threshold -200 mV
Differential Limits -11V to +14V
Single-Ended High Voltage 2.5V to 10V
Single-Ended Low Voltage -1V to +1V
Input Resistance, Typ. 17 kOhm
Quadrature Position Mode
Zero Adjust -999999 to +999999
Span Adjust 0 to ±999999
Quadrature Rate Mode
Conversion Technique Inverse period
Output Update Rate 30 ms + 0-2 signal periods
Gate time Selectable 10 ms to 199.99 s
Time Before Zero Output Selectable 10 ms to 199.99 s
Time Base Accuracy Calibrated to ±2 ppm
Zero Adjust -999999 to +999999
Span Adjust 0 to ±999999
Analog Output (standard)
Output Levels 4-20 mA, 0-20 mA, 0-10 Vdc, -10 to +10Vdc (user selectable)
Compliance, 4-20 mA 10V (0-500 ohm load)
Compliance, 0-10V 2 mA (5 kOhm load)
Output Resolution 16 bits (65,536 steps)
Output Accuracy ±0.05% of output span
Output Update Rate 25/sec max
Output Isolation 250V rms working, 2.3 kV rms per 1 minute test
Serial Data Output (standard)
Signal Types RS232 or RS485 (half or full duplex), jumper selectable
Data Rates 300, 600, 1200, 2400, 4800, 9600, 19200 baud
Output Isolation 250V rms working, 2.3 kV rms per 1 min test
Serial Protocols Modbus TCP, Modbus RTU, Modbus ASCII, TDM ASCII
Modbus Compliance Modbus over Serial Line Specification V1.0 (2002)
Ethernet Connector RJ45 jack for 10/100 Base-T Ethernet cable
RS232/RS485 Connector  Screw terminals for easy daisy chaining 
Digital Addresses 247 for Modbus, 31 for TDM ASCII
Dual Relay Output (standard)
Relay Type Two solid state relays, SPST, normally open, Form A
Load Rating 120 mA at 140 Vac or 180 Vdc
Sensor Excitation Output (standard)
Output Levels 5V@100 mA, 10V@120 mA, 24V@50 mA (jumper selectable)
Output Isolation 50V from signal ground
Power Input
Standard Power 85-264 Vac or 90-300 Vdc
Low Power Option 10-48 Vdc or 12-32 Vac
Power Frequency DC or 47-63 Hz
Power Isolation 250V rms working, 2.3 kV rms per 1 min test
Power Consumption 2W typical, 3W with max excitation output
Mechanical
Dimensions 129 x 104 x 22.5 mm case
Mounting 35 mm rail per DIN EN 50022
Electrical Connections Plug-in screw-clamp connectors
Environmental
Operating Temperature 0°C to 55°C
Storage Temperature -40°C to 85°C
Relative Humidity 95% at 40°C, non-condensing
Cooling Required Mount transmitters with ventilation holes at top and bottom. Leave 6 mm (1/4") between transmitters, or force air with a fan.
Pinout
 LT transmitter pinout
Applications Examples
Using Quadrature for Cutting to Length
Using quadrature panel meters or transmitters to cut material to length Controlling the repetitive cutting of material to length is an excellent application of a quadrature transmitter or quadrature meter.
The quadrature encoder shares the shaft of a sensing wheel, whose rotation corresponds to lineal displacement of material. The transmitter compares the displacement reading against setpoint information, and then uses its dual relays to first slow down and then cut the material.
Using Quadrature for X-Y Positioning
Using quadrature panel meters or transmitters for X-Y positioning Accurate X-Y position or rate can be obtained from two shaft encoders, which convert linear position to quadrature signals as a shaft turns. In addition to serving as a transmitter, each transmitter or meter can use its optional dual relay setpoint capability for closed loop control.
Using Quadrature to Monitor a Drilling Operation
Uswing quadrature meters or transmitters to monitor an oil drilling operation Quadrature can be used to track position and vertical drilling speed of the bit in an oil drilling operation. A shaft encoder is rotated by a cable that moves with the drilling shaft. In this application, the same encoder signal is applied to a quadrature transmitter for position, and to a second quadrature transmitter for rate. Both transmitters can send a 4-20 mA signal to a control room and be alarmed.

In this application, quadrature provides much higher immunity to noise and jitter than a magnetic pickup.

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