user manual

The converter is comprised of a 4th-order, delta-sigma (Δ∑) analog-to-digital

(A/D) converter modulator followed by a programmable digital filter. A flexible

input multiplexer handles differential or single-ended signals; the programmable

filter allows the user to optimize between a resolution of up to 23 bits noise-free.

Examples of scan sequences, with various channel resolutions and calibration

arrangements, appear in Table 5-1 on page 5-2.

4.7 Input Ranges

You can individually select the input range for each channel. For example, one

channel could be used for volts and another for temperature. Omega’s OM-

DAQ-USB-2401 automatically assigns the appropriate units depending on two

factors:

• The selected range and

• Measurement unit preferences

Measurement unit preferences can be modified from the Omega DAQ Central

‘Channels’ tag of the ‘Configuration’ window. Chapter 4 provides more detailed

information.

The maximum voltage input range (full scale) is –10 to +10

Vdc. The lowest programmable voltage input range is -30mV

to +30 mV. A complete list of the OM-DAQ-USB-2401’s

programmable ranges appears on page 8-1.

Each analog input channel has the following user-specified measurement

parameters:

• Signal type: volts, or thermocouple type J, K, T, E, R, S, B, or N

• Full scale voltage: from -10 to + 10 Vdc; with programmable ranges as

indicated on page 8-1.

• Resolution/sample period: from 22.5 bit RMS at 0.153 samples/sec, to 17 bit

RMS at 50 samples/sec or greater

These rates were obtained with a 16-channel scan.

4.8 Analog Input Configuration

The OM-DAQ-USB-2401 includes 16 analog signal inputs which may be used as

16 single-ended inputs, 8 differential inputs, or as a combination of single-ended

and differential inputs with up to 16 connections.

Single-ended inputs are used with signals that share the same common low

(COM), such as multiple batteries which have their negative sides connected in

common. Differential inputs are required when signals do not share the same

common low, such as in the typical use of thermocouples.

Software

4-15

NOTE: