- OMEGA OMB-DBK Option Cards/Module User Guide

Input Signal Conditioning Configuration
Hardware settings affect 3 aspects of signal conditioning:
• Input circuit selection: analog or digital
• Attenuation selection
• Low-pass filter selection.
Input Circuit Selection
Each input channel can be set for the analog or digital circuit. Two jumpers must be set for each channel.
Select the input circuit for each input channel as follows:
1. Determine the best circuit type for each channel.
•
The digital input circuit works best for DC-coupled signals where the low level is less than
0.5 V and the high level is above 2.5 V and the voltage does not exceed ±15 V. By using a
pull-up resistor, switches and relays can create the signal. Frequencies can be as high as
960 kHz. The digital input circuit does not attenuate or filter the input signal.
•
The analog input circuit is AC-coupled and is sensitive to signals from 100 mV to 84 V p-p.
It also provides attenuation and low-pass filtering to reduce the effects of noise.
2. Position the input circuit jumpers for analog or digital (see figure). Verify that both jumpers for a
channel are set the same (JP3 and JP4 for channel 0; JP23 and JP24 for channel 1;
JP43 and JP44 for channel 2; and JP63 and JP64 for channel 3).
Default
Analog
Attenuation Selection (Analog Input Circuit Only)
When measuring strong analog signals, the attenuator can reduce the input sensitivity and the effects of
noise. If enabled, the attenuator reduces the input sensitivity by a factor of about 20.
Set the attenuation for each channel as follows:
1. Determine the best attenuation for each channel.
•
Use attenuation and reduced sensitivity if the input signal’s peak level exceeds 1 V.
•
Disable attenuation for full sensitivity if the input signal’s peak level is less than 1 V.
2. For attenuation, position the jumper across pins 1 and 2. Attenuation is enabled (the default setting).
(See figure.)
Default
Attenuation Enabled
(Reduced
Sensitivity)
3. To disable attenuation, position the jumper across pins 2 and 3.
The full-strength signal is used.
DBK7, pg. 6 879895 DBK Option Cards and Modules