turck EZ-track, Руководство пользователя

Страница: 6 / 20

6 B1403
www.turck.com • Phone: 763-553-7300 • Application Support: 1-800-544-7769 • Fax: 763-553-0708 • Turck Minneapolis, MN 55441
Chapter 3: EZ-track Q21-DQ Overview
3 .1: Quadrature Output
The output from the transducer can be wired directly to any incremental encoder input card, without the need for a special
converter module or PLC interface card designed specifically for use with a pulsed output magneto-restrictive transducer .
The quadrature output provides absolute position data in engineering units . This means that the need for the calibration
constant (wire speed) programming has been removed, thereby eliminating the possibility of having an improperly
calibrated system . The output signal wires are driven by differential line drivers, similar to the drivers used in most pulsed type
transducers, providing a high degree of noise immunity .
A unique feature of this transducer is a “burst” mode of operation . An input on the transducer triggers a data transfer of all the
incremental position data relative to the transducer’s absolute zero position . This can be used to achieve absolute position
updates when power is restored to the system or anytime an update is needed to re-zero or home the machine . Additionally,
another input to the transducer can be used to establish a “zero” position for the transducer .
3 .2: Signal Connection Application Note
Overview
This application note will clarify the input and output signals of the Q21-DQ LDT probe .
Inputs
The quadrature probe has two inputs, the “zero” and “burst” inputs . These inputs are “single ended” . That is, the connection for
each input consists of only one wire, the corresponding signal wire . For these single ended inputs, the signal is measured with
reference to the power supply ground, which is sometimes referred to as “common” .
The quadrature probe is available with 24 VDC level signal thresholds or TTL level thresholds . The signal voltage level
required to activate the input for the +24 VDC level signal is approximately 41% of the power supply voltage .
* For example, if the power supply voltage powering the probe is exactly 24VDC, the threshold voltage would be
approximately 9 .84 volts .
The TTL level threshold signals are activated when these inputs exceed the typical TTL level threshold, which is 2 .0 VDC .
Additionally, for the 24 VDC level signals, either a “sourcing” or “sinking” type of input can be specified . A “sourcing” input type
is pulled high internal to the probe . To activate a “sourcing” input, the customer must pull the signal lower than the threshold
voltage to activate the input . A “sourcing” input is usually driven by a “sinking” output or a switch connected to ground .
A “sinking” input type is pulled low internal to the probe . To activate a “sinking” input, the customer must pull the signal
higher than the threshold voltage to activate the input . A “sinking” input is usually driven by a “sourcing” output or a switch
connected to the power supply .
It is important that the customer drive the signal levels much greater or lower than the threshold voltages . Asserting a signal
with a voltage level close to the threshold voltage could induce multiple activations of that input (or none at all) and therefore
produce unexpected results or probe readings .