Teledyne BDS-3960 Setting Software Parameters Filter, Gas Factor, Tmp. Coeff

Oxygen Analyzer Maintenance

amplifier. The range of this count is the same as the BDS sensor, 0000 to 4095. The last digit is a status digit—zero indicates the I/O PCB is in normal mode. If the I/O PCB receives a remote command to zero or span, it will let the PPC program know through this digit.

Zero Offset line displays the actual Analog to Digital count of the electronics plus sensor offset stored in the memory of the PPC. The lower the number the better, but a high number does not hinder the performance of the sensor very much. One reason for a high count could mean that the sensor is still drifting downward and therefore an additional zero calibration might be needed to maintain accuracy.

Span Factor displays a number which is a factor needed to convert digital counts to PPB oxygen concentration. This number should be between 10 and 40.

AmpGain/RangeID/DAC displays the command sent to the I/O PCB and determines what gain the amplifier should have and what range ID contact should open. Both numbers are from 0 to 4. Usually, with default ranges, they should be the same but not necessarily.

DAC is a count number sent to the analog to digital converter of the I/O PCB. This sets the output for the concentration 0-1 vdc and 4-20 madc outputs. Its range is from 0 to 4095. A large discrepancy between AmpGain and RangeID would point to a hardware problem e.g.: AmpGain/RangeID/DAC: 0/4/265.

4.3.2Setting Software Parameters: Filter, Gas Factor, Tmp. Coeff.

There are three parameters that are under the control of the user and are accessible from the parameter selection box as shown below. These are:

•Digital filter—noise reduction

•Gas Factor—compensates for different background gases

•Temperature coefficient—corrects baseline drift due to temperature.

Teledyne Analytical Instruments 45