AMETEK 955DQ Brik LDT User Manual

Page 17

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Frequency or Pulse Rate

Selecting the proper frequency in the LDT’s part number
is very important. The 955DQ has an internal update
time of 1 millisecond 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 955DQ is fac-
tory set from 1KHz - 1.00MHz, consult part number for
your model. The input for the PLC or display will deter-
mine the frequency needed.

Example: If your PLC High Speed counter card or dis-
play accepts a 1MHz encoder input, the choices are

A1 = 1KHz
A2 = 2KHz
A3 = 5KHz

F1 = 10KHz
F2 = 25KHz
F3 = 50KHz
F4 = 75KHz
F5 = 100KHz

F6 = 150KHz
F7 = 250KHz
F8 = 500KHz
F9 = 1.00MHz

Note: If your controller’s maximum input frequency falls
between two available frequencies, choose the lower
frequency.

3.6 955DQ

Output Drivers

The 955DQ BRIK uses a 0L7272 line driver IC. Your LDT
was conﬁgured at the factory for either a TTL level output
or a 13.5 - 30 VDC level output. Refer to label on LDT for
your output type.

D = Differential RS-422 line driver, TTL compatible

L = Differential line driver 13.5 - 30VDC
V out = V in (LDT Power) -1 volt

Option D 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.