The DI-2108 vs. the DI-2108-P

At first glance, it would appear that the DI-2108 and the DI-2108-P are one and the same. Both the DI-2108 and the DI-2108-P do feature ±10V full scale measurement ranges, and include 7 digital ports, with dedicated Rate and Count inputs. In addition both are in 6.68″W × 3.28″D × 1.13″H polycarbonate ABS enclosures, and can acquire data to a PC hard drive using WinDaq, or operate in stand-alone mode. That’s where the similarities end.

Under the hood, there are three very significant differences.

Selectable Gain

While the DI-2108 does have a ±10V full-scale measurement range, the gain is fixed at 1. The DI-2108-P on the other hand, has a ±10V measurement range at a gain of 1, with selectable gain ranges of ±2.5, ±5, ±10, 0-5 and 0-10 Volts. This is particularly beneficial when you’re attempting to display and record low-level signals, say 0-500mV or the 1 to 5V signal produced when acquiring 4-20mA data using a 250Ω shunt resistor. See our application note on gain and dynamic range for more on this.

Not only does the DI-2108-P feature selectable gain ranges, it provides true 16-bit analog-to-digital resolution over those ranges. Higher resolution means more precise measurements. The DI-2108, with a fixed ±10V measurement range, features 12 to 16-bit resolution that is sample-rate-dependent (see the chart below).

Channel Expansion Using ChannelStretch

Often times, an application calls for more than 8 channels. Using our proprietary ChannelStretch technology, the DI-2108-P can be daisy chained to other DI-2108-Ps, for expansion up to 128 total channel. Channels from multiple DI-2108-P loggers can be displayed in a single instance of WinDaq, and all synchronously-recorded data is stored in a single file.

The DI-2108 features 8 channels, and cannot be daisy chained to other DATAQ data loggers. You can connect multiple DI-2108s to a single PC, and run a separate instance of WinDaq for each. In this case, each instance of WinDaq will generate it’s own data file.

Armored Analog Inputs

Analog channels on the DI-2108 are protected up to ±100 V without damage. The DI-2108-P ups that protection to ±150 V without damage, with an impressive common mode range of ±220V.

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