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Datasheets and User Guides

App Notes

Software & Driver

 

2.7 - AIN

AIN Overview


The LabJack UE9 has 14 user accessible analog inputs built-in. All the analog inputs are available on the DB37 connector, and the first 4 are also available on the built-in screw terminals.

The analog inputs have variable resolution, where the time required per sample increases with increasing resolution. The value passed for resolution is from 0-17, where 0-12 all correspond to 12-bit resolution, and 17 still results in 16-bit resolution but with minimum noise. The UE9-Pro has an additional resolution setting of 18 that causes acquisitions to use the alternate high-resolution converter (24-bit sigma-delta). Resolution is configured on a device basis, not for each channel.

The analog inputs are connected to a high impedance input buffer. The inputs are not pulled to 0.0 volts, as that would reduce the input impedance, so readings obtained from floating channels will generally not be 0.0 volts. The readings from floating channels depend on adjacent channels and sample rate. See Section 2.7.3.8.

When scanning multiple channels, the nominal channel-to-channel delay is specified in Appendix A, and includes enough settling time to meet the specified performance. Some signal sources could benefit from increased settling, so a settling time parameter is available that adds extra delay between configuring the multiplexers and acquiring a sample. The passed settling time value is multiplied by 5 microseconds to get the approximate extra delay. This extra delay will impact the maximum possible data rates.