
ENDEVCO 6634C
INSTRUCTION MANUAL
IM6634C
Page 4-7
Different filter conditions can be selected for each input type (PE, Velocity Coil, RCC Input) and output mode. The
new filter condition choices are stored as the defaults for each input type and output mode in non-volatile memory.
B.
CUTOFF FREQUENCIES
To remotely set a Cutoff Frequency (-3 dB point), send one of the following commands to the 6634C:
Lnnnnn ;
Set lower cutoff to nnnnn, where nnnnn is Hz in floating point
decimal format. Its value is equal to 0.(byte0)(byte1)
(byte2)(byte3) E (byte4).
Unnnnn ;
Set upper cutoff to nnnnn, where nnnnn is Hz in floating point
decimal format. Its value is equal to 0.(byte0)(byte1)
(byte2)(byte3) E (byte4).
If new filter cutoff frequency is successfully setup, no response will be provided by the 6634C. If a problem is
encountered, and the unit is in Listener/Talker mode, one of the two error messages (E0XXXX "BEL", filter not
installed or E1XXXX "BEL", setup is not allowed) will be provided by the 6634C.
The High and Low Pass Filters provide 36 dB/octave rolloffs with the allowable Cutoff (-3dB) Frequency ranges as
follows:
Lower Cutoff (High Pass)
5 to 500 Hz
Upper Cutoff (Low Pass)
50 to 5000 Hz, Jumper selected
100 to 10,000 Hz, Jumper selected
NOTE: The -5% frequency point can be obtained by multiplying the Cutoff Frequency by 1.2 for the high pass
filter and by 0.833 for the low pass filter.
To determine the current filter cutoff settings, send the following commands to the 6634C (after selecting the
specific 6634C unit as Listener/Talker using the InnXXX; command):
L?XXXX ;
Request current lower cutoff frequency for high pass filter
U?XXXX ;
Request current upper cutoff frequency for low pass filter
Unit responds with:
Lnnnnn "ACK"
where nnnnn is lower cutoff frequency in floating point decimal format.
Unnnnn "ACK"
where nnnnn is upper cutoff frequency in floating point decimal format.
After the new filter cutoff frequency(ies) are successfully implemented, the unit returns to Normal Mode. (If filter
cutoff frequency(ies) cannot be implemented, unit provides "Err" message if in Listener/Talker mode and then
returns to normal mode.) Different filter cutoff frequencies can be selected for each input type and output mode.
The new filter cutoff frequency settings are stored as the defaults for each input type and output mode in non-
volatile memory.