USB-2408 Serie

The USB-2408’s digital outputs default to powering up as high (5V). Primarily this is because the pull jumper (J6) is set at our factory to the Up (5V) position. However, changing this jumper to the Down position is not the answer to achieve digital outputs that power up low. While doing so will cause the outputs will power up low, they will not be usable, since then they can never be set to high due to their architecture being “open drain”. Writing out a “1” in software shorts the output to ground, while wring out a “0” allows the “pull” voltage to reach the output (note that open drain has inverted logic). We chose to design the outputs to be open drain on the USB-2408 and USB-2416 models so that they could control much higher currents than traditional TTL/CMOS logic. However, one trade-off is that powering up as low is not possible. If you are switching a solid-state relay, you could choose a relay that itself has inverted logic.

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For the USB-2408 (and USB-2416), do not use the Composite VIs. Instead, use the analog input VIs, and both your voltage and thermocouple channels will be read properly. Here is a link to an FAQ with an example VI: http://kb.mccdaq.com/KnowledgebaseArticle50396.aspx

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InstaCal does play a role in configuring the analog channels of the USB-2408, but not in configuring its digital channels. Also close InstaCal all the way before launching LabVIEW (do not have both applications open). Below is a knowledgebase article that includes a downloadable example VI that uses the digital channels for both input and output in LabVIEW: http://kb.mccdaq.com/KnowledgebaseArticle50354.aspx

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Hello, Interrupt on Change is not supported by the USB-2408. Please contact Sales Engineering at 1-800-234-4232 Ext-3 for assistance with selecting a product that supports Interrupt on Change.

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Figure 7 in the USB-2408’s hardware manual (PDF) shows the typical differential thermocouple connections. Differential is required for thermocouples, to best reject noise common to both wires of a thermocouple. Attempting to read a thermocouple in single ended mode will have too much noise to be useful. Also be sure to set the datarate (not the sample rate) to either 50 Hz or 60 Hz, depending upon your local power grid’s frequency, to help reject that particular noise. Our ULx driver (through our underlying UL driver) for LabVIEW handles the cold junction compensation and linearization for you. This is rather complex and there is rarely a benefit of attempting to performing them yourself (also our ULx driver does not give you a way to read the CJC sensor alone).

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The USB-2408 Series hardware does support using a mix of Single-Ended (SE) & Differential (DIFF) Inputs, together in the same acquisition. You must designate each channel pair as either SE or DIFF, usually done in InstaCal, or done in DAQami if that is the software package being used. Take care to note which channel numbers to have your software sample from (as the numbering is different between SE and DIFF).

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The USB-2408 is supported by two of our “Out of the Box” applications, DAQami and TracerDAQ. Either application will allow you to acquire and generate data. DAQami and TracerDAQ also support data logging to a file and allow for file conversion to a CSV format, for use within Excel.

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There is no user-accessible offset adjustment on MCC’s thermocouple measurement devices. No offset adjustment should be required to meet specified accuracy for USB-2408 units that have been in service for < 1 year (since factory calibration). If you feel that the temperatures are offset on the order of 1 or 2 deg C, then try preventing excessive airflow over the USB-2408’s screw terminals. An error of 10’s of degrees indicates an incorrect setting for your type thermocouple wire. If the offset error is << 1 deg C, then it is most likely within the overall accuracy spec of the USB-2408, or it could be error in the thermocouple itself or in the standard that you are comparing the USB-2408 to.

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The lowest input range supported on the USB-2408 and USB-2416 is +- 0.078125V. You can select any of the supported inputs ranges when in single ended or differential mode. Open circuit detection is only supported when in thermocouple mode.

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Hello VH - Be sure to not have InstaCal and DASYLab open at the same time. The result may be that channel settings made in InstaCal are not picked up by DASYLab. Drag the Analog Input module, from the MCC-DRV module list, to the worksheet. Double click on it, and note that this module defaults to one channel. Double click on additional channels at the top (to turn a blue channel icon to orange). The result, after you close the window, will be additional channel terminals appearing on the right side of the module icon.

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Hello JP – the Upgrade price to go from DASYLab Version 10 to Version 13 would depend on which version of DASYLab you currently own (Lite, Basic Full, Pro) Please give us a call to discuss this upgrade. Yes, we will give you the $49 credit that you spent on DAQami towards a DASYLab upgrade.

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Hello JP, Yes, you can use 2 or more USB-2408s on a single PC to increase your channel count. Each USB-2408 will require its own USB port. Below are the software packages that will support multiple USB devices: TracerDAQ PRO, Universal Library for Windows, UL for Android, ULx for NI LabVIEW, and DASYLab. Based on our discussion yesterday, you have DASYLab BASIC v10. My recommendation would be to upgrade your current license to v13. Your other options would be to upgrade to TracerDAQ PRO or use one of the supplied programming libraries and develop your own custom program. At this time DAQami only supports 1 USB device so if your desire is to use DAQami then you will need to purchase the USB-2416.

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Yes, the $599.00 price for the USB-2408 includes our MCC DAQ CD which includes InstaCal, TracerDAQ (virtual Instrument suite), the Universal Library for Microsoft .NET, the UL for Android , and our ULx drivers for NI LabVIEW. Yes, with the use of a shunt resistor you can measure current using the USB-2408. For example if we were to assume that you have a 4-20mA input signal you could use a 250 ohm shunt resistor which would create a voltage drop of 1-5 volts with 1 volt equal to 0.004A and 5 volts equal to 0.020A. To calculate your resistance value simply use Ohms law (I = E/R).

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Hello Serchu, Yes, our DAQ devices are compatible with DC based LVDT sensors. Our expertise here at MCC is with our DAQ hardware but the LVDT sensors that I am familiar with generally require a 10 -30 VDC excitation source and output a +- 5 volt or a 4-20 mA signal based on its displacement.

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The legacy UL for LabVIEW did not support 24 bit A/D data, and thus it cannot be used for voltage measurements on the USB-2408. Temperature measurements do work, so thermocouples could be used. If you can’t update to a newer LabVIEW version, you could make analog measurements by directly calling the cbVIn function in our DLL. Contact our Technical Support folks for more info if needed.

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Hello Eric, There are two likely issues you may be seeing. First there is a known issue, listed in the ULx help file that is specific only to LabVIEW 2009. Secondly, independent of the LabVIEW version: For the USB-2408 and USB-2416, all channels are considered to be “voltage” channels, not temperature channels, even if some of your channels are measuring thermocouples. There is an FAQ on this topic here: http://kb.mccdaq.com/KnowledgebaseArticle50481.aspx

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Measurement Computing recently released Android (tablet/smartphone) support for several USB products. Unfortunately, the USB-2408 is currently not one of them. You can view all of the Android supported hardware here: http://www.mccdaq.com/daq-software/universal-library-android.aspx

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The USB-2408-2AO is not a web enabled DAQ device. We offer a library for the Android OS that you can use with various DAQ devices on your smartphone. https://www.mccdaq.com/daq-software/universal-library-android.aspx We also offer the WebDAQ 316 and the WebDAQ 504. Both are Web Enabled DAQ devices that allows date to be accessed and viewed from anywhere on an internet-enabled device. https://www.mccdaq.com/internet-enabled-data-loggers

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With LabVIEW closed all the way, configure one or more channels in InstaCal for thermocouple type N, and also set the datarate to 60 Hz (for best noise rejection). Then close InstaCal and launch LabVIEW. Now when you make a voltage measurement on those channels, the data will automatically be returned in Degrees Celsius. i.e. you do not need to know the CJC value, since our driver will perform all the calculations for you.

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Hello Paolo - please see the below KB article for more information on this topic: http://kb.mccdaq.com/KnowledgebaseArticle50584.aspx

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Thank you for your inquiry. I reviewed your question and the USB-2408-2AO will support your application requirements. One thing to note is that the USB-2408 series supports an aggregate sample rate of 1000Hz. So if you need to sample your inputs at a faster rate you will require a different product. The -2AO version also supports 2 analog outputs. However, I do not see a requirement for analog outputs therefore, if you need a faster 24 bit DAQ device our USB-2404-10 would be a good choice. As for software I would recommend that you use our DASYLab graphical programming language. Please feel free to give us a call if you would like to discuss this further.

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