Ametek Gemco Brik 955QD Series Installation, Programming And Maintenance Manual page 16

Chapter 3: 955QD Overview
3.6: 955QD
Frequency or Pulse Rate
Selecting the proper frequency in the LDT's part number is very important. The internal clock inside
of the 955QD interrogates the LDT approximately every 1 millisecond on LDT's less than 60" in length
and approximately every 2 milliseconds on the units greater than 60" in length. The LDT transmits the
incremental pulses at a xed rate; all incremental pulses must be transmitted before the LDT will interrogate
itself again. The frequency or pulse rate of the 955QD is factory set to 10KHz - 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:
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.
Output Drivers
The 955QD Brik uses a 0L7272 line driver IC. Your LDT was congured at the factory for either a TTL level
output or a 10 - 30VDC level output. Refer to label on LDT for your output type.
D = Differential RS-422 line driver, TTL compatible
L = Differential line driver 10 - 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 input cards that are not TTL compatible.
13 Installation, Programming and Maintenance Manual