turck EZ-track, Manual

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3 .5 Features (continued)
ZERO Pulse
By sending an input signal to the probe at any point in the stroke, a new zero point can be established . When using the burst
input, the absolute position provided will be relative to the programmed zero position . In probes with volatile storage the
zero point will be kept until a new zero pulse is sent or until the probe loses power . Probes with nonvolatile storage will store
the zero position even if you lose power . The nonvolatile zero can be set 100,000 times; the volatile zero can be set an infinite
number of times .
3 .6 Q21-DQ
Frequency or Pulse Rate
Selecting the proper frequency in the LDT’s part number is very important . The Q21-DQ has an internal update time of 1 milli-
second on LDT’s less than 60” in length and approximately 2 milliseconds on the units greater than 60” in length . The LDT will
stretch the amount of pulses travelled over the update rate . All incremental pulses must be transmitted before the LDT will
interrogate itself again . The frequency or pulse rate of the Q21-DQ is factory set from 1KHz - 1 .00MHz, consult part number for
your model . The input for the PLC or display will determine the frequency needed .
Example: If your PLC High Speed counter card or display accepts a 1MHz encoder input, the choices are
NOTE:
If your controller’s maximum input frequency falls between two available frequencies, choose the lower frequency .
Output Drivers
The Q21-DQ LDT uses a 0L7272 line driver IC . Your LDT was configured at the factory for either a TTL level output or a 10 - 30
VDC level output . Refer to label on LDT for your output type .
R = Differential RS-422 line driver, TTL compatible
L = Differential line driver 10 - 30VDC
V out = V in (LDT Power) -1 volt
Option R has a 5 volt TTL level output regardless of input power .
Option L has an output of 1 volt less than probe input power . This option is used when driving higher voltage input cards and
is not TTL compatible .
A = 10KHz
B = 25KHz
C = 50KHz
D = 75KHz
E = 100KHz
F = 150KHz
G = 250KHz
H = 500KHz
I = 1 .00MHz