How to Build a Current Loop System with Isolated M Series? Hardware: Multifunction DAQ (MIO)>>M Series
Problem: I want to build a 4 - 20 mA current loop system with Isolated M Series Device. Which module should I use and configurations are possible? Solution: When picking your Isolated M Series DAQ device for a current loop application, there are a few aspects that are important to note since not just any basic Analog Input module will suffice. Isolation - Without properly isolating the DAQ device, a ground loop can form. Ground loops may cause offset errors in your measurements. Also, large common mode voltages caused by ground potential differences can dammage any DAQ Device. Shunt Resistor - Most all DAQ devices measure voltage. A highly effective and accurate method of measuring current is to place a precision shunt resistor between the leads of the DAQ amplifier to convert the current signal into a voltage measurement. The Isolated M Series DAQ devices that contain these two aspects and are suitable for current loop systems are: PCI-6236
PXI-6236 PCI-6238 PXI-6238 PCI-6239 PXI-6239 All Isolated M Series DAQ devices do not have external power supplies attached to them. This will require placing the power supply in line with the transducer which is modeled in Figure 1 as a current source.  Figure 1 Related Links: Attachments:
Report Date: 02/21/2008 Last Updated: 02/22/2008 Document ID: 4IKHMCSG |
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