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Digilent WebDAQ 904 User Manual

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WebDAQ 904 User's Guide
June 2024
About this User's Guide
What you will learn from this user's guide
This user's guide describes the WebDAQ 904 data acquisition device, the WebDAQ web interface, and lists device
specifications.
Where to find more information
Additional information about the WebDAQ Series of internet enabled data loggers is available on our website at
digilent.com. You can also contact Digilent with specific questions.
•
WebDAQ web interface: Open the Help window for information about using WebDAQ software.
•
WiFi adapters approved for use with the WebDAQ Series:
•
Tech support:
Digilent Forum
For international customers, contact your local distributor. Refer to the
website.
Hazardous voltages
Take the following precautions if you connect hazardous voltages to the WebDAQ 904. A hazardous
voltage is a voltage greater than 42.4 Vpk or 60 VDC to earth ground.
•
Ensure that hazardous voltage wiring is performed only by qualified personnel adhering to local
electrical standards.
•
Do not mix hazardous voltage circuits and human-accessible circuits on the same device.
•
Make sure that devices and circuits connected to the WebDAQ are properly insulated from human
contact.
Hazardous locations: The WebDAQ 904 is not certified for use in hazardous locations.
Other product and company names mentioned may be trademarks of their respective owners.
USB WiFi Adapters
International Distributors section
Copyright Digilent, Inc. All rights reserved.
1300 Henley Court
Pullman, WA 99163
www.digilent.com
on our
Page 1 of 31

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Summary of Contents for Digilent WebDAQ 904

  • Page 1 June 2024 About this User’s Guide What you will learn from this user’s guide This user’s guide describes the WebDAQ 904 data acquisition device, the WebDAQ web interface, and lists device specifications. Where to find more information Additional information about the WebDAQ Series of internet enabled data loggers is available on our website at digilent.com.

  • Page 2: Powered By Raspberry Pi

    WebDAQ 904 User’s Guide Introducing the WebDAQ 904 The WebDAQ 904 is part of the WebDAQ Series of Internet enabled data loggers. WebDAQ 904 is a universal input data acquisition and logging device designed for multipurpose testing. The WebDAQ 904 provides the following features: •...
  • Page 3 The link-local address is valid only for communications between the WebDAQ and the host PC to which it is connected. Copyright Digilent, Inc. All rights reserved. Page 3 of 31 Other product and company names mentioned may be trademarks of their respective owners.

  • Page 4: Connecting The External Power Adapter

    79 and up. Not recommended for use with earlier versions of the Edge browser. Not recommended for use with Internet Explorer. Copyright Digilent, Inc. All rights reserved. Page 4 of 31 Other product and company names mentioned may be trademarks of their respective owners.

  • Page 5: Configuring The Webdaq For Wireless Communication

    4. Disconnect the Ethernet cable from the LAN connection. Wait a few seconds and refresh the browser window. Copyright Digilent, Inc. All rights reserved. Page 5 of 31 Other product and company names mentioned may be trademarks of their respective owners.

  • Page 6: Configuring The Network Router For Communication Across Networks

    CONFIG RESET button. When pressed, the default network and security settings are written to the device and the WebDAQ is rebooted. Factory default settings. Parameter Specification IP address 192.168.0.101 Subnet mask 255.255.255.0 Copyright Digilent, Inc. All rights reserved. Page 6 of 31 Other product and company names mentioned may be trademarks of their respective owners.

  • Page 7: Functional Details

    Functional Details Functional block diagram Device functions are illustrated in the block diagram shown here. Figure 2. WebDAQ 904 functional block diagram Copyright Digilent, Inc. All rights reserved. Page 7 of 31 Other product and company names mentioned may be trademarks of their respective owners.

  • Page 8: Front Panel Components

    Spring terminals (Analog connections) Connect up to four analog inputs to the 6-position detachable spring terminals (CH0 to CH3). Copyright Digilent, Inc. All rights reserved. Page 8 of 31 Other product and company names mentioned may be trademarks of their respective owners.

  • Page 9: Timing Modes

    • Do not connect any signals to terminals 1 and 2. Timing modes The WebDAQ 904 supports high-resolution, 50 Hz rejection, 60 Hz rejection, and high speed timing modes. Copyright Digilent, Inc. All rights reserved. Page 9 of 31 Other product and company names mentioned may be trademarks of their respective owners.

  • Page 10: Analog Input Circuitry

    • The A/D converter measures voltage across the CH+ and CH- terminals. • The WebDAQ 904 has ±60 V, ±15 V, ±4 V, ±1 V, and ±125 mV voltage ranges. Current mode Figure 7. Current circuitry. Copyright Digilent, Inc. All rights reserved.
  • Page 11 The WebDAQ 904 has a ±25 mA current range. Thermocouple mode Figure 8. Thermocouple circuitry. The WebDAQ 904 uses the ±125 mV range of the ADC to return a voltage reading. Each channel has a built-in thermistor for cold-junction compensation (CJC) calculations. Minimizing thermal gradients Changes in the ambient air temperature near the front connector, or a thermocouple wire conducting heat directly to terminal junctions, can cause thermal gradients.
  • Page 12 The WebDAQ 904 compensates for lead wire resistance in hardware if all the lead wires have the same resistance. • The WebDAQ 904 applies a gain of 2x to the voltage across the negative lead wire and the ADC uses this voltage. 2-wire Resistance and quarter-bridge mode Figure 11.
  • Page 13 The internal excitation voltage varies based on the resistance of the sensor. Copyright Digilent, Inc. All rights reserved. Page 13 of 31 Other product and company names mentioned may be trademarks of their respective owners.

  • Page 14: Rear Panel Components

    POWER LED blinks yellow. The operating system automatically powers off the device at the end of the shutdown procedure. Copyright Digilent, Inc. All rights reserved. Page 14 of 31 Other product and company names mentioned may be trademarks of their respective owners.

  • Page 15: Function Button

    2: STATUS Flashing green 100 ms Waing for a scheduled start condition to be met. on/2s off) Copyright Digilent, Inc. All rights reserved. Page 15 of 31 Other product and company names mentioned may be trademarks of their respective owners.

  • Page 16: Sd Card Slot

    When removable media is plugged into the WebDAQ, the operating system opens it for writing. Use the FUNC button or web interface to unmount the SD card before removing. Copyright Digilent, Inc. All rights reserved. Page 16 of 31 Other product and company names mentioned may be trademarks of their respective owners.
  • Page 17 If you generate data that exceeds the capacity of the selected storage location, a "File too large" error is returned and the acquisition stops. To avoid interruptions, select a storage location with a large capacity. Copyright Digilent, Inc. All rights reserved. Page 17 of 31...

  • Page 18: Power-On Mode

    To automatically run a schedule when the WebDAQ powers up, enable the “Automatically start schedule on system startup” option on the Schedule Settings dialog box of the web interface. If a power cycle occurs, the Copyright Digilent, Inc. All rights reserved. Page 18 of 31...

  • Page 19: Replacing The Battery

    In the web server’s Help, refer to the “Updating WebDAQ Firmware” topic or FAQ for instructions. Calibrating the hardware The Digilent Test department performs the initial factory calibration. Contact Digilent when calibration is required. The recommended calibration interval is one year.

  • Page 20: Specifications

    80 dB at 50 Hz ratio (NMRR) High resolution 65 dB at 50 Hz and 60 Hz Copyright Digilent, Inc. All rights reserved. Page 20 of 31 Other product and company names mentioned may be trademarks of their respective owners.
  • Page 21 ±300, ±1000 2-wire resistance mode accuracy depends on the lead wire resistance. This table assumes 0 Ω of lead wire resistance. Copyright Digilent, Inc. All rights reserved. Page 21 of 31 Other product and company names mentioned may be trademarks of their respective owners.

  • Page 22: Input Noise

    High resolution rejection rejection Voltage, ±60 V Voltage, ±15 V 10.8 Voltage, ±4 V 10.8 Voltage, ±1 V Copyright Digilent, Inc. All rights reserved. Page 22 of 31 Other product and company names mentioned may be trademarks of their respective owners.

  • Page 23: Excitation Level

    Table 8. Digital input/output specifications. Parameter Specification Digital type CMOS (Schmitt trigger) input / open drain output Copyright Digilent, Inc. All rights reserved. Page 23 of 31 Other product and company names mentioned may be trademarks of their respective owners.

  • Page 24: Ethernet Connection

    100 kΩ pull-up resistor of that particular digital input/output bit to the internal 5 V supply. Careful consideration should be made when considering the external pull-up resistor value and the resultant pull-up voltage produced at the load. Copyright Digilent, Inc. All rights reserved. Page 24 of 31...

  • Page 25: Network Configuration

    Flash: 4 GB eMMC (3 GB available for user data storage) Shared folders and mapped drives are reset when factory defaults are restored. Copyright Digilent, Inc. All rights reserved. Page 25 of 31 Other product and company names mentioned may be trademarks of their respective owners.

  • Page 26: Usb Ports

    The USB ports are provided for connection to a mass storage device or approved WiFi adapter. Use the WebDAQ software to configure start and stop settings for jobs and schedules. Copyright Digilent, Inc. All rights reserved. Page 26 of 31...

  • Page 27: Push Buttons

    (default) Refer to this circuit board image for the location of the W1 jumper. Copyright Digilent, Inc. All rights reserved. Page 27 of 31 Other product and company names mentioned may be trademarks of their respective owners.
  • Page 28 If using a different supply, ensure that it has a positive center pin. Copyright Digilent, Inc. All rights reserved. Page 28 of 31 Other product and company names mentioned may be trademarks of their respective owners.

  • Page 29: Safety Voltages

    WebDAQ operation is intended for indoor use only, but may be used outdoors if installed in a suitable enclosure. Copyright Digilent, Inc. All rights reserved. Page 29 of 31 Other product and company names mentioned may be trademarks of their respective owners.

  • Page 30: Signal Connector

    MAINS building installations of Measurement Categories CAT II, CAT III, or CAT IV. Caution! Do not connect the WebDAQ 904 to signals or use for measurements within Measurement Categories II, III or IV.

  • Page 31: Screw Terminal

    Digital bit 2 DIO0 Digital bit 0 DIO3 Digital bit 3 DIO1 Digital bit 1 Digital ground Copyright Digilent, Inc. All rights reserved. Page 31 of 31 Other product and company names mentioned may be trademarks of their respective owners.