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WebDAQ 904 Datasheet
Internet Enabled Universal Input Logger

Highlighted Features

The WebDAQ 904 intelligent logger features universal inputs and remotemonitoring and control of real-time data.

Overview• Four 24-bit simultaneous analog inputs;
individually configurable:o Voltage (up to ±60 V), current, RTD,
thermocouples, resistance, bridge-based
sensors• 100 S/s/ch sample rate, max• Voltage and current excitation• Four isolated DIO for triggers and alarms• Log data to internal storage or mapped
network storage• Share folders to view files over a local
network• Export data to csv, UFF, or binary for use inother applications• Alarm and event notifications with email and
SMS messaging• Easy, flexible task scheduling• Configurable read/write access• No driver software to install• Built-in web server• Remote monitoring and control• WiFi support

The WebDAQ 904 is a stand-alone universal input logger
designed for remote monitoring and control. All theintelligence is built into the WebDAQ, eliminating the need for
a PC or additional software. By using the embedded WebDAQ
web server, users can easily configure simple or sophisticated applications, log sensor data, update digital outputs
and/or send notifications based on alarm conditions, and view real-time data from any location and any device witha web browser.
The WebDAQ 904 performs high-accuracy measurements from up to four analog inputs. Users can measureseveral signals from sensors such as strain gauges, RTDs, thermocouples, and load cells. Housed in a heavy-duty
chassis, the WebDAQ 904 is rugged enough for industrial applications.

Integrated Software and Hardware
The WebDAQ Series embedded OS and web server provides an all-in-one package for stand-alone data logging andalarming. Users can monitor and control their applications from anywhere with a web browser.
The WebDAQ web server is optimized for both desktop and mobile use. Users can perform data acquisition tasks
from phones, tablets, and laptops with a single, intuitive user interface.
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WebDAQ 904 Datasheet – Rev 1, June 2024

Remote Access and Control
Install the WebDAQ 904 on any network and access it using any device with a web browser to remotely monitor
and control all operations.

Wireless Communication
After the WebDAQ is detected on a wired network, users can connect an approved WiFi adapter to the rear panel
and communicate with the WebDAQ over a wireless network. Refer to our website for a list of the WiFi adapters
approved for use with WebDAQ Series hardware.

Flexible Triggering
Start or stop the acquisition based on analog or digital thresholds, alarm states, or date/time values. On-demand
push button triggering is also supported.

WebDAQ Web Interface
An embedded web server provides a clean, intuitive interface to access all configuration and data managementtasks.
Hardware, trigger, and alarm settings are contained in a single task, or “job”. Multiple “jobs” can be run in a“schedule” for more complex data logging applications.
For example, users can create a schedule of jobs in which one job automatically runs after an alarm condition istriggered on a different job, such as when a temperature is reached or when a digital input changes.

Device-independent operation lets you remotely monitor and control the WebDAQ 904 from any device with a web browser.

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Other product and company names mentioned may be trademarks of their respective owners.

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WebDAQ 904 Datasheet – Rev 1, June 2024

Introduction
Easy Setup – Powerful Capabilities
Jobs are the building blocks of WebDAQ. The ability to define different data logging jobs, or tasks, and add them toa schedule unleashes flexibility not seen in any other data logger.
Whether you want to set up a simple logging task or a complex task, jobs and a schedule make it easy andstraightforward.

What is a Job?

What is a Schedule?

The basic building block of WebDAQ, a job defineschannel configuration, logging options, start and stop
conditions, and alarming.

A schedule is a collection of jobs that gives flexibility todynamically change data logging attributes, such as
sampling rate, active channels configuration, or alarm levels.

Example:Switching from static acquisition to dynamic
acquisition.
1 Schedule and 2 Jobs
Users can easily set up a job for a slow, static acquisition
and a fast dynamic acquisition. When a trigger condition
is met (i.e. over/under alarm), Job 1 (slow acquisition)ends and Job 2 (fast acquisition) begins. When thetrigger condition returns to normal, job 1 can berestarted.

Clear, Concise, Data Displays
WebDAQ users don’t need to rely on the small screensand difficult to navigate displays of most other loggers.
With WebDAQ’s intuitive web interface, users can easily
see their data and alarm conditions in real time or after
the acquisition is complete.

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Other product and company names mentioned may be trademarks of their respective owners.

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WebDAQ 904 Datasheet – Rev 1, June 2024

Features
Alarm and Event Notifications
Create multiple alarms using analog or digital channel
sources. Configure alarms to reset and re-arm when
the condition clears or reset them remotely with yourbrowser. View the alarm status on the web interface.
Users can configure one or more events to record
when a job is started, stopped, or triggered, or if anerror condition is detected.
Receive alarm and event notifications on one or more
addresses using email and SMS messaging.

Virtually Unlimited Storage
Store data files and configuration settings locally ininternal flash memory or save to external media or
network folders. Users can map a network drive or
FTP server as the location to log data or store files.
Easily transfer files between WebDAQ storage
locations and mapped network storage locations.

Share Folders
Users can share a WebDAQ storage location or
specific folder over a local network.

(high resolution mode). Refer to the Specifications
section for the conversion times for all timing modes.

Universal Input Modes
Each channel is configurable for a different input
mode:• Voltage• Current• Thermocouples• RTD (4-wire and 3-wire)• Resistance (4-wire and 2-wire)• Bridge-based sensors (half- and full-bridge,
and other powered load cells)
Measurement ranges vary for each type ofmeasurement; refer to the Specifications section forrange values per input mode. The max sample rate is
100 S/s per channel.
Voltage and current excitation is provided for
applicable input modes. Each channel has a built-in
thermistor for cold-junction compensation (CJC)
calculations when measuring thermocouples. An
analog pre-filter removes noise that may be present
in the signals prior to conversion.

Real-Time Data Display
View data as it is acquired or from a stored file. Users
can specify a range of data to view and zoom in or out.
Data is plotted on strip chart and scalar displays.

Control Read and Write Access
Users can control who can view and modify job
settings by defining a password and setting thesecurity level for the admin account. A “share”
password can be used to access a shared folder or FTP
server running on the WebDAQ.

Run the Schedule on Startup
Automatically run the schedule when the systemstarts up. Multiple jobs in the schedule are runconsecutively.

Real-Time ClockA real-time clock provides an absolute time reference
for timestamping data. The clock can be set to any
time zone and may be synchronized to the internet
time server.

Analog Input
The WebDAQ 904 provides four individuallyconfigurable channels of 24-bit universal analog
input. All channels are measured simultaneously at
rates of up to 10 ms (high speed mode) or 510 ms

Timing Modes
The WebDAQ 904 supports high resolution, 50 Hz
rejection, 60 Hz rejection, and high-speed timing
modes.
• High resolution mode optimizes maximum
overall noise rejection and provides
rejection of 50 Hz and 60 Hz noise.
• 50 Hz rejection mode optimizes 50 Hz noise
rejection.
• 60 Hz rejection mode optimizes 60 Hz noise
rejection.
• High speed timing mode optimizes the
sample rate.

Isolated Digital I/O
The four isolated digital I/O lines can be used either
as triggers to start or stop the acquisition or as alarm
outputs.

Flexible Power Requirements
Provide power with the 9 volt, 2.2 amp supply thatships with the device, or connect any 6 to 16 DC
supply.

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Other product and company names mentioned may be trademarks of their respective owners.

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WebDAQ 904 Datasheet – Rev 1, June 2024

Firmware Updates
Device firmware is bundled with the operating
system and web server in one update file. This
allows the WebDAQ to be updated in the field.

Calibration
The WebDAQ is factory-calibrated using a NISTtraceable calibration process. Specifications areguaranteed for one year. Return the device to thefactory for recalibration.

REST API
The WebDAQ REST API allows users to communicate
with the device outside of the web interface toretrieve information about the system, schedules,
and jobs, get acquisition and alarm status, and to
start/stop an acquisition.

Functional Block Diagram

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WebDAQ 904 Datasheet – Rev 1, June 2024

Front and Rear Panels
Front Panel
Detachable spring and screw terminals allow quick analog and digital connections.

Rear Panel
The rear panel provides Ethernet and power connections, LED indicators, dual USB ports, one SD card slot, buttons,
and a ground connector.

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WebDAQ 904 Datasheet – Rev 1, June 2024

Specifications
All specifications are subject to change without notice. Typical for 0 °C to 50 °C unless otherwise specified.
Analog Input
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Number of channels: 4 analog input channels
ADC resolution: 24 bits
Type of ADC: Delta-Sigma (with analog prefiltering)
Sampling mode: Simultaneous
Input modes: Voltage, Current, Resistance (4-wire and 2-wire), RTD (3-wire and 4-wire), Thermocouple,
Quarter-bridge, Half-bridge, Full-bridge
Conversion time, no channels in TC modeo High speed: 10 ms for all channels
o Best 60 Hz rejection: 110 ms for all channels
o Best 50 Hz rejection: 130 ms for all channels
o High resolution: 500 ms for all channels
Conversion time, one or more channels in TC modeo High speed: 20 ms for all channels
o Best 60 Hz rejection: 120 ms for all channels
o Best 50 Hz rejection: 140 ms for all channels
o High resolution: 510 ms for all channels
Overvoltage protection: terminals 3 through 6, across any combination: ±60 V
Input impedanceo Voltage mode (±60 V, ±15 V, ±4 V): 1 MΩ
o Current mode: <40 Ω
o All other modes: 1 GΩ
Input bias current: <1 nA
Integral non-linearity (INL): ±15 ppm
Common mode rejection ratio (CMRR)o fin = 60 Hz: >100 dB
Normal mode rejection ratio (NMRR)o Best 60 Hz rejection: 90 dB at 60 Hz
o Best 50 Hz rejection: 80 dB at 50 Hzo High resolution: 65 dB at 50 Hz and 60 Hz

Input mode
Voltage
Current
Thermocouple
4-wire and 2-wire resistance
4-wire and 3-wire RTD
Quarter-bridge
Half-bridge
Full-bridge

Input mode ranges
Nominal range(s)±60 V, ±15 V, ±4 V, ±1 V, ±125 mV±25 mA±125 mV
10 kΩ, 1 kΩ
Pt 1000, Pt 100
350 Ω, 120 Ω±500 mV/V±62.5 mV/V, ±7.8 mV/V

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Actual range(s)±60 V, ±15 V, ±4 V, ±1 V, ±125 mV±25 mA±125 mV
10.5 kΩ, 1.05 kΩ
5.05 kΩ, 505 Ω
390 Ω, 150 Ω±500 mV/V±62.5 mV/V, ±7.8125 mV/V

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WebDAQ 904 Datasheet – Rev 1, June 2024
Accuracy
Gain error (% of reading)
Offset error (ppm of range)
Typical 25 ºC, ±5 ºC, –40 to 70 ºC max±0.3, ±0.4±20, ±50±0.3, ±0.4±60, ±180±0.3, ±0.4±240, ±720
±0.1, ±0.18±15, ±45±0.1, ±0.18±120, ±360±0.1, ±0.6±30, ±100±0.1, ±0.5±120, ±320±0.1, ±0.5±1200, ±3200±0.1, ±0.5±240, ±640
±0.1, ±0.5±2400, ±6400±0.1, ±0.5±2400, ±6400±0.1, ±0.5±2400, ±6400±0.03, ±0.07±300, ±450±0.03, ±0.08±300, ±1000±0.03, ±0.08±2200, ±8000±1 ºC, typicalMode, range
Voltage, ±60 V
Voltage, ±15 V
Voltage, ±4 V
Voltage, ±1 V
Voltage/Thermocouple, ±125 mV
Current, ±25 mA
4-wire and 2-wire resistance, 10 kΩ*
4-wire and 2-wire resistance, 1 kΩ*
4-wire and 3-wire RTD, Pt 1000
4-wire and 3-wire RTD, Pt 100
Quarter-bridge, 350 Ω
Quarter-bridge, 120 Ω
Half-bridge, ±500 mV/V
Full-bridge, ±62.5 mV/V
Full-bridge, ±7.8 mV/V
CJC sensor accuracy*2-wire resistance mode accuracy depends on the lead wire resistance. This table assumes 0 Ω of lead wire resistance.

Stability
Gain drift (ppm of reading/ºC)
±20
±20
±20
±10
±10
±15
±15
±15
±15
±15
±15
±15
±3
±3
±3

Mode, range
Voltage, ±60 V
Voltage, ±15 V
Voltage, ±4 V
Voltage, ±1 V
Voltage/thermocouple, ±125 mV ±Current, ±25 mA
4-wire and 2-wire resistance, 10 kΩ
4-wire and 2-wire resistance, 1 kΩ
4-wire and 3-wire RTD, Pt 1000
4-wire and 3-wire RTD, Pt 100
Quarter-bridge, 350 Ω
Quarter-bridge, 120 Ω
Half-bridge, ±500 mV/V
Full-bridge, ±62.5 mV/V
Full-bridge, ±7.8 mV/V

Offset drift (ppm of reading/ºC)
±0.2
±0.8
±3.2
±0.2
±1.6
±0.4
±3
±30
±6
±60
±120
±240
±20
±20
±20

Input NoiseMode, range
Voltage, ±60 V
Voltage, ±15 V
Voltage, ±4 V
Voltage, ±1 V

High speed
7.6
10.8
10.8
7.6

Conversion time
Best 60 Hz rej.
Best 50 Hz rej.
1.3
1.3
1.9
1.9
2.7
2.7
1.3
1.3

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High resolution
0.5
0.7
1.3
0.5

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WebDAQ 904 Datasheet – Rev 1, June 2024
Input Noise
Conversion time
Best 60 Hz rej.
Best 50 Hz rej.

High resolution

10.8

1.9

1.9

1.0

10.8

1.9

1.9

1.0

4.1

1.3

0.8

0.3

7.1

1.8

1.2

0.7

7.6

1.7

1.1

0.4

10.8

1.9

1.9

0.9

Quarter-bridge, 350 Ω

5.4

1.0

1.0

0.7

Quarter-bridge, 120 Ω
Half-bridge, ±500 mV/V
Full-bridge, ±62.5 mV/V
Full-bridge, ±7.8 mV/V

5.4
3.8
5.4
30

1.0
0.5
1.0
4.7

1.0
0.5
1.0
4.7

0.7
0.2
0.8
2.3

Mode, range
Voltage/thermocouple, ±125mV ±Current, ±25 mA
4-wire and 2-wire resistance,
10 kΩ
4-wire and 2-wire resistance,
1 kΩ
4-wire and 3-wire RTD, Pt
1000
4-wire and 3-wire RTD, Pt
100High speed

Excitation level
Load resistance (Ω)

Measurement conditions
700
240
350
120

Half-bridge
Full-bridge

120
350
1,000
10,000

Excitation (V)
2.5
2.0
2.7
2.2

Resistance, RTD, and quarter-bridge mode excitation level
Load resistance (Ω)
Excitation (V)
50
150
430
2,200

Digital input/output
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Digital type: CMOS (Schmitt trigger) input / open drain output
Number of I/O: One port of 4 bits
Configuration: Bit configurable for input or output
Power on conditions: Power on reset is input mode
Pull-up configuration: Each bit is pulled up to 5 V with a 100 kΩ resistor
Input frequency range: DC – 10 kHz. Applying a signal with a higher frequency will adversely affect system
performance and could cause errors.
Input high voltage threshold: 1.9 V min, 3.6 V max
Input low voltage threshold: 2.3 V max, 1.0 V min
Schmitt trigger hysteresis: 0.6 V min, 1.7 V max

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Page 9 of 13

WebDAQ 904 Datasheet – Rev 1, June 2024
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Input high voltage limit: 15 V absolute max
Input low voltage limit: –0.5 V absolute min, 0 V recommended min
Output voltage range: 0 V to +5 V (no external pull up resistor), 0 V to +15 V max**
Output off state leakage current: 10 µA max
Output sink current capability: 100 mA max (continuous) per output pin
Output transistor on-resistance (drain to source): 1.6 Ω** The external pull-up resistor is connected between the digital output bit and external supply. Adding an external pull-up resistor connects it inparallel with the internal 100 kΩ pull-up resistor of that particular digital input/output bit to the internal 5 V supply.

Network•••••

Ethernet type: 100 Base-TX, 10 Base-T
Communication rates: 10/100 Mbps, auto-negotiatedConnector: RJ-45, 8 position
Cable length: 3 meters (9.84 feet) max
Additional parameters: HP Auto-MDIX support

Network configuration
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Network IP configuration: DHCP, link-local, static DHCP may be disabled by the user and a static IP address
assigned. If DHCP is enabled but is unsuccessful at obtaining an IP address the device will fall back to linklocal and request the IP address 169.254.100.100.
Network device name: The name used for detecting the device using mDNS (zero-conf). This name may bechanged using the web interface.
Network name publication: By mDNS
User accounts: admin and share. These accounts are case-sensitive and cannot be changed using the webinterface.

Factory default settings
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Factory default IP address: 192.168.0.101
Factory default subnet mask: 255.255.255.0
Factory default Gateway: 192.168.0.1
Factory default DHCP setting: DHCP + link-local enabled
Factory default password for admin account: admin. Passwords are case sensitive and can be changed
using the web interface.
Factory default password for share account: share. Passwords are case sensitive and can be changed using
the web interface.
Factory default device name: webdaq-xxxxxx, where xxxxxx is the last 6 digits of the MAC address (printed
on the label on the underside of the device).
Note: When factory defaults are restored, any shared folders or mapped drives are reset.

USB ports•••

Number of USB ports: Two, for connection to a mass storage device or approved WiFi adapter.
USB device type: USB 2.0 (high-speed).
Device compatibility: USB 1.1, USB 2.0, USB 3.0

SD memory card slot

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Page 10 of 13

WebDAQ 904 Datasheet – Rev 1, June 2024••

Memory card type: SD, SDHC, SDXC, MMC, TransFlash.
File systems supported: FAT16, FAT32, exFAT, ext2/3/4, NTFS.

Push buttons•••

Power (POWER):o W1 jumper installed (factory default): Turns device on or off.
o W1 jumper removed (device on when power is applied): Reboots the device.
Function (FUNC): Unmounts external media, or starts/stops an acquisition.
Reset (CONFIG RESET): Restores network and alarm settings to factory default values.

Ground connector•

Connector port for the #6-32 ground screw.

Power
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Input voltage: Center positive. 6 VDC to 16 VDC.
Input wattage: 4 W typ, 10 W max.
External AC adapter: 9 VDC, 2.2 amps, 110 VAC to 240 VAC input range.
Battery: One 3 V button cell lithium battery required to maintain time of day clock when device ispowered off. Replace with Panasonic BR-1225 3V lithium coin cell battery or equivalent. See user’s guidefor the replacement procedure.
Note: refer to the user’s guide for behavior when jumper W1 is installed or removed.

Shock
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Operating shock: 30 g, 11 ms half sine; 18 shocks at 6 orientations.

Mechanical••

Dimensions (L × W × H): 158.8 × 146.1 × 38.1 mm (6.25 × 5.75 × 1.50 in.).
o With BNC connectors: 178.8 × 146.1 × 38.1 mm (7.04 × 5.75 × 1.50 in.)
Weight: 680 g (1.5 lb).

Environmental
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Temperature range: 0 °C to 50 °C max (Operating), –40 °C to 85 °C (Storage).
Ingress protection: IP 30.
Humidity: 10- 90% RH, noncondensing (Operating), 5-95% RH (Storage).
Maximum altitude: 2,000 m (6,562 ft)
Pollution degree: 2
The WebDAQ 904 is intended for indoor use only.

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WebDAQ 904 Datasheet – Rev 1, June 2024

Order Information
HardwarePart No.

Description

6069-410-007-1

WebDAQ 904: Internet enabled universal input logger with four analog inputs,
simultaneous sampling, support for multiple measurement types, embedded operating
system and web server; includes the ATS018T-W090V power supply with USA, UK, andEurope plugs.

Accessories
Part No.

Description

6069-240-005

ACC-205: DIN-rail mounting kit; requires the ACC-404 panel/ wall mounting kit.

6069-240-006

ACC-404: Panel/wall mounting kit; use with the ACC-205 to mount on a DIN rail.

6069-240-000

J Type Thermocouple (Length: 1 Meter)

6069-240-001

J Type Thermocouple (Length: 2 Meter)

6069-240-004

T Type Thermocouple (Length: 2 Meter)

6069-240-002

K Type Thermocouple (Length: 1 Meter)

6069-240-003

K Type Thermocouple (Length: 2 Meter)

WebDAQ Series

6069-410-005-1

WebDAQ 316: Internet enabled data logger with 16 thermocouple inputs and 4 DIO lines,
embedded operating system and web server; includes the ATS018T-W090V power supply
with USA, UK, and Europe plugs.

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WebDAQ 904 Datasheet – Rev 1, June 2024

6069-410-006-1

WebDAQ 504: Internet enabled vibration and acoustic logger with four analog inputs,
simultaneous sampling, IEPE signal conditioning, embedded operating system and web
server; includes the ATS018T-W090V power supply with USA, UK, and Europe plugs.

About Digilent
Digilent is committed to making engineering accessible, offering competitive pricing, portable products, andcomprehensive documentation. Specializing in test and measurement devices, Xilinx-based FPGA development
boards, a variety of expansion modules for customizing applications, and robust options for DAQ and datalogging,our design philosophy champions your creativity. By emphasizing speed, modularity, customizability, and worldclass support, we provide the building blocks while you bring the brilliance.

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