The U6-Pro has all the features of the normal U6 with the addition of the auxiliary low-speed hi-resolution (24-bit) sigma-delta ADC. This converter takes about 125 ms per sample and provides an effective resolution of about 22-bits over the 0 - 5 or ±5V ranges. Linearity and accuracy also improved compared to the normal converter. 

The LabJack U6 has 14 external analog inputs (AIN0-AIN13). AIN0-AIN3 are available on screw terminals and also on the DB37 connector. All 14 analog inputs are available on the DB37 connector.

The maximum input range is ±10 volts, with software selectable gains of x1, x10, and x100. Each analog input can be measured single-ended, or differentially in even/odd pairs. Analog input resolution is 16 bits at max speed (~20us conversion time), increasing to 18+ bits at slower speeds (see sections 3.1 and 3.2 of manual). Input impedance is at least 1 GOhm, with typical input bias currents of only 10 nA. Command/response (software timed) analog input reads typically take 1-4 ms depending on number of channels and communication configuration. Hardware timed input streaming has a maximum rate that varies with resolution from 4 k samples/s at 18 bits to 50 k samples/s at 16 bits.

The U6-Pro has all the features of the normal U6 with the addition of an auxiliary low-speed high-resolution (24-bit) sigma-delta ADC. Analog input resolution varies from 19.5 bits (RMS or Effective) at max speed (4 ms conversion time), to 22 bits at slower speeds (160 ms conversion time). 

The LabJack U6 has a temperature sensor located very close to the AIN0-AIN3 screw-terminals. Accuracy is ±2 degrees C (max). This sensor is particularly useful for thermocouple cold junction compensation (CJC). The LabJack U6 has 2 fixed current outputs of 10 uA and 200 uA. These are useful for measuring resistance. The LabJack U6 has 2 analog outputs (DAC0 and DAC1) that are available both on screw terminals and the DB37 connector. Each analog output can be set to a voltage between about 0 and 5 volts with 12-bits of resolution. The analog outputs are based on a true voltage reference. The analog outputs are updated in command/response mode, with a typical update time of 1-4 ms depending on communication configuration.

The LabJack U6 has 20 digital I/O channels which can be individually configured as input, output-high, or output-low. The first 4 FIO are available on screw terminals and the DB37 connector. All 8 FIO and 3 MIO are available on the DB37 connector, and 8 EIO and 4 CIO are available on the DB15 connector. Note that on the U6, CIO0-CIO2 are the same as MIO0-MIO2. Command/response (software timed) reads/writes typically take 1-4 ms depending on communication configuration. The digital inputs can also be read in a hardware timed input stream where up to 16 inputs count as a single stream channel.

Up to 4 digital I/O can be configured as timers. The timers are very flexible, providing options such as PWM output, pulse timing, pulse counting, and quadrature input. For more information about the timers see Section 2.10 and Appendix A of the User's Guide. The User's Guide can be found on the U6 downloads page. Up to 2 digital I/O can be configured as 32-bit counters. Since counting is one possible mode of the timers above, the U6 has up to 6 counting inputs. All I/O lines on the U6 are protected against minor over voltages. The AIN lines can withstand continuous over voltage of ±?? volts, the FIO lines can withstand up to ±10 volts, while the EIO/CIO/MIO lines can withstand up to ±6 volts.

By using USB hubs or Ethernet switches, many LabJacks can be interfaced to a single PC, providing an inexpensive solution for low-speed high channel count applications.