Omega Engineering OM-DAQ-USB-2401 manual Power Line Rejection, Optical Isolation, A/D Conversion

4Software

4.4 Power Line Rejection

The OM-DAQ-USB-2401 Series can take readings while making use of 50/60Hz line cycle rejection. While in the line cycle rejection mode, the maximum sample rate is as follows:

•50 Hz rejection: Scan Rate (SR) Range: 0.153Hz < SR <= 1Hz

•60 Hz rejection: Scan Rate (SR) Range: 1Hz < SR <= 1.667Hz

OMB-DAQ-USB-2401 Series Block Diagram

Power LED
	Isolation
	Barrier
	Power Supply
	Isolated
Power Jack	Power Supply

Local Power

USB
Jack
USB	MCU
Controller	32Bit
Activity LED
	Digital Isolators

CJC

4 Analog Inputs

+12v

Gain = x2, 1/8

+12v output Excitation voltage

CJC

4

Analog Inputs

MUX

SE/		PGIA
DI
			Gain =
			x1,2,4,8,16
	32,64

+12v output
Excitation voltage	1MΩ
CJC
4
Analog Inputs
+12v
+12v output
Excitation voltage
CJC	MUX
4
Analog Inputs
+12v output
Excitation voltage

	MUX	PGA	24–Bit
1MΩ			A/D

Gain = x2, 1/8

SE/	PGIA
DI

1MΩ 1MΩ

Figure 4-25. OM-DAQ-USB-2400 Block Diagram

4.5 Optical Isolation

Your DAQ unit is optically isolated from its host PC by up to 500 Vdc. This means that an inadvertent application of such voltage to the DAQ unit will not affect the PC. In addition to isolation, the device maintains all sensitive acquisition-related circuitry external to the PC. This physical isolation of circuitry from the PC results in less noise and more accurate measurements.

4.6 A/D Conversion

	OM-DAQ-USB-2401 uses an extremely low-noise, 24-bit analog-to-digital (A/D)
	converters. They provide complete high-resolution measurement solutions for
4-14	the most demanding applications.