Measurement Computing WebDAQ 504 User manual

WebDAQ 504 User's Guide
September 2019. Rev 4
Contents
About this User's Guide
Introducing the WebDAQ 504
Seng up the WebDAQ
Funconal Details
Specificaons
EU Declaraon of Conformity
Trademark and Copyright Informaon
Measurement Compung Corporaon, InstaCal, Universal Library, and the Measurement Compung logo are
either trademarks or registered trademarks of Measurement Compung Corporaon. Refer to the Copyrights &
Trademarks secon on mccdaq.com/legal for more informaon about Measurement Compung trademarks.
Other product and company names menoned herein are trademarks or trade names of their respecve
companies.
© Measurement Compung Corporaon. All rights reserved. No part of this publicaon may be reproduced,
stored in a retrieval system, or transmied, in any form by any means, electronic, mechanical, by photocopying,
recording, or otherwise without the prior wrien permission of Measurement Compung Corporaon.
Noce
Measurement Compung Corporaon does not authorize any Measurement Compung Corporaon product
for use in life support systems and/or devices without prior wrien consent from Measurement Compung
Corporaon. Life support devices/systems are devices or systems that, a) are intended for surgical implantaon
into the body, or b) support or sustain life and whose failure to perform can be reasonably expected to result in
injury. Measurement Compung Corporaon products are not designed with the components required, and are
not subject to the tesng required to ensure a level of reliability suitable for the treatment and diagnosis of
people.
About this User's Guide
This user's guide describes the Measurement Compung WebDAQ 504 data acquision device, the WebDAQ
web interface, and lists device specificaons.

Where to find more informaon
Addional informaon about the WebDAQ Series of internet enabled data loggers is available on our website at
www.mccdaq.com/WebDAQ. You can also contact Measurement Compung Corporaon with specific
quesons.
WebDAQ web interface: Open the Help window for informaon about using WebDAQ soware.
Knowledgebase: kb.mccdaq.com
WiFi adapters approved for use with WebDAQ Series hardware: www.mccdaq.com/pdfs/manuals/wd-
wifi.pdf
Tech support form: www.mccdaq.com/support/support_form.aspx
Email: [email protected]
Phone: [phone] and follow the instrucons for reaching Tech Support
For internaonal customers, contact your local distributor. Refer to the Internaonal Distributors secon on our
website at www.mccdaq.com/Internaonal.
Hazardous voltages
Take the following precauons if you connect hazardous voltages to the WebDAQ 504. 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 locaons: The WebDAQ is not cerfied for use in hazardous locaons.
Contents
WebDAQ 504 User's Guide
page 2

Introducing the WebDAQ 504
The WebDAQ 504 is part of the WebDAQ Series of Internet enabled data loggers. WebDAQ 504 is a
vibraon/acousc data acquision and logging device that provides the following features:
4 simultaneously sampled analog inputs
24-bit resoluon
Data rates up to 51.2 kS/s per channel
AC/DC coupling
IEPE signal condioning
An-aliasing filters
Overvoltage protecon
Four bidireconal, isolated DIO
10/100 Ethernet interface
Support for USB WiFi adapters for wireless connecvity
Support for USB mass storage devices and SD cards for data logging or file transfer
Powered by an external power supply (included)
WebDAQ Series devices are designed with an integrated operang system and web interface. You communicate
with the device over a network connecon using the web interface opened in a web browser.
Mobile support – access the WebDAQ from any device with a web browser, such as a phone or tablet
Remote monitoring and control
Run simple to complex logging operaons
Flexible task scheduling
Powered by Raspberry Pi
The WebDAQ is designed with the Raspberry Pi Compute Module, featuring a quad core processor with speeds
up to 1.2 GHz, 1 GB RAM and 4 GB Flash memory.
Integrated operang system and web service
The WebDAQ is a complete data acquision system containing an embedded operang system and web server.
The operang system resides in internal flash memory, and includes a web service and device driver. All
configuraon, acquision, and data management is performed using the web interface.
Ethernet interface
The WebDAQ has a built-in 10/100 BASE-T auto-negoaon, high-speed communicaon port. You can access
and configure your WebDAQ from anywhere with access to the network to which it is connected. A unique
MAC address is assigned to each device at the factory. You configure the Ethernet connecon sengs through a
web interface. The default network device name uses the format webdaq-xxxxxx, where xxxxxx are the lower
six digits of the factory-assigned MAC address. You can change this name with the web interface.
Open-source soware
WebDAQ firmware uses open-source soware components. Refer to Licenses for the licensing informaon of
each component. Open-source code is available upon request from inf[email protected].
WebDAQ 504 User's Guide
page 3

Funconal block diagram
Device funcons are illustrated in the block diagram shown here.
Figure 1. Funconal block diagram
Saving large data files
If you expect to acquire a large amount of data to a single file when logging to external media, do not use
media formaed with the FAT32 file system. FAT32 is limited to a 4 GB maximum file size. If the log file on
FAT32 media grows beyond that size, a "File too large" error is returned and the acquision stops. Before
starng a logging session of this type, reformat the media using a different file system such as NTFS. Refer to
the Frequently Asked Quesons help topic for more informaon about file systems.
Unpacking
As with any electronic device, you should take care while handling to avoid damage from stac
electricity. Before removing the board from its packaging, ground yourself using a wrist strap or by simply
touching the computer chassis or other grounded object to eliminate any stored stac charge.
Contents
WebDAQ 504 User's Guide
page 4

Seng up the WebDAQ
Connecng to a local area network
The WebDAQ 504 requires a TCP/IP connecon to a network or the Ethernet port of a computer. A standard
Ethernet cable is shipped with the device. The WebDAQ IP address type is set by default for DHCP/Link-Local.
When connected to a network, the device first aempts to receive an IP address from a DHCP server. If this
fails, a link-local address is used. Use of a stac address requires configuraon via the web interface. The IP
address idenfies the WebDAQ 504 on the network, and is used to access the web interface.
Connecng to a network with DHCP enabled
Connect one end of the Ethernet cable to the connector on the WebDAQ rear panel, and connect the other end
to a 10Base-T or 100Base-TX compable Ethernet port, hub, or switch.
Once the device is detected, DHCP assigns an address. A different address may be assigned each me the
hardware is connected to the network.
WiFi support
Aer successfully configuring a wired connecon, you can use the web interface to configure the
WebDAQ for wireless communicaon. Refer to the Configuring the WebDAQ for wireless
communicaon secon for more informaon.
Connecng directly to a PC
Connect one end of the Ethernet cable to the connector on the WebDAQ rear panel, and connect the other end
directly to the Ethernet port on a PC. The WebDAQ aempts to communicate with the host PC using
169.254.100.100 – the link-local address stored on the device. The host PC may accept this address or use a
different address. The link-local address is valid only for communicaons between the WebDAQ and the host PC
to which it is connected.
Connecng the external power adapter
Connect the network cable before connecng to external power
Connecng to the external supply before installing on a network results in the device aempng to
auto-negoate a network address before one is available.
An external power adapter is included with each shipment (PS 9V1AEPS230V).
Connect the adapter to the power connector labeled EXT PWR on the device rear panel, and plug the AC
adapter into an electrical outlet.
Press the POWER buon. The POWER LED on the rear panel turns yellow as the hardware starts up, and green
when it is ready for use.
WebDAQ 504 User's Guide
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Detecng the device on a network
WebDAQ uses the "zeroconf" zero-configuraon protocol to announce its presence on a local area network.
Zeroconf uses a device name which can be accessed from other computers on the network.
Zero-configuraon networking is helpful to find your WebDAQ hardware on the network
The easiest way to add zeroconf support to Windows is to install Bonjour Print Services. Bonjour
soware is Apple's implementaon of zero-configuraon networking, and is readily available as a free
download – open a browser window and search for Bonjour Print Services.
Zeroconf is built into popular applicaons such as Apple ITunes® and instant messaging soware, so
your computer may already support it.
Many Linux systems will have the avahi version of zeroconf installed by default, so it’s likely zeroconf is
available if you’re running Linux.
Accessing the WebDAQ web interface
To access the WebDAQ web interface, open a browser window and enter hp://webdaq-xxxxxx.local, where
xxxxxx is the last 6 digits of the MAC address. The MAC address is on a label at the boom of the WebDAQ
enclosure.
If your network is configured for the zeroconf protocol, the WebDAQ web interface opens.
If the web interface does not open or an error is returned, install a device discovery tool such as Bonjour
Print Services. Refer to the note above about zero-configuraon networking.
The WebDAQ web interface is shown here. Note that this figure shows a WebDAQ schedule that includes two
jobs.
Figure 2. WebDAQ web interface
Use the WebDAQ web interface to configure hardware and acquision opons, schedule and run jobs, and to
view and manage data. The Help window provides details about all components on the web interface.
Once a connecon is established and you can communicate to the device, you can change the configuraon for
other network scenarios.
* The latest version of Chrome, Firefox, Safari, UC Browser, or Opera recommended. Compable with IE v11
with the latest Windows Updates installed. Not recommended for use with other IE versions or the Edge
browser.
WebDAQ 504 User's Guide
page 6

Configuring the WebDAQ for wireless communicaon
Once communicaon is established on a wired network, you can connect a WiFi adapter to the USB port and
use the web interface to configure the WebDAQ for communicaon over a wireless network. With the WebDAQ
connected through the wired connecon, perform the following procedure.
1. Connect an approved WiFi adapter to the USB port on the WebDAQ rear panel.
A list of WiFi adapters approved for use with WebDAQ Series hardware is available on our website at
www.mccdaq.com/pdfs/manuals/wd-wifi.pdf.
2. Open the WebDAQ web interface in a browser window and go to the Device window, Network tab.
3. Select WiFi. Once the list of available networks updates, select the wireless network that you want to
connect to, and enter the password, if any.
If the connecon is successful, the selected wireless network will show above this list with a checkmark
next to it.
You can click on the selected network to open a WiFi Network Sengs dialog box where you can forget the
current network or configure the IP address type (DHCP/Link-Local or Stac).
4. Disconnect the Ethernet cable from the LAN connecon.
Changing to a wireless network may require a reboot
If a connecon can't be established aer changing the network, you may need to reboot the operang
system and restart the WebDAQ using the Power buon.
Configuring the network router for communicaon across networks
To communicate with the WebDAQ over the internet from a computer connected to a different network, you
must change the network configuraon of the network router.
Cauon! This procedure should only be performed by a network administrator or computer
professional. Incorrect sengs can significantly disrupt a network.
In the following procedure, the WebDAQ is installed on the host LAN, the computer is installed on the client
LAN, and it is assumed that you have successfully connected the device to a local network.
1. Determine the IP address of the WebDAQ – open the Device window from the web interface, and note the
IP Address value on the Network Sengs tab.
2. Configure your router so that the address determined above is a stac address. The procedure for
accomplishing this varies between routers; refer to your router documentaon for instrucons.
3. Configure the firewall/router to forward an unused port to port 80 on the WebDAQ at the IP address
configured for the device. Note the stac IP address assigned to the router – this is referred to as the WAN
address.
4. To access your WebDAQ from a remote locaon, enter the WAN address followed by the port selected
above preceded by a colon in the web browser. The format of the address entered in the browser is:
00.000.00.00:00000 (WAN address of router:port selected for the WebDAQ).
WebDAQ 504 User's Guide
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Security
Use the web interface to set the level of access to the website and to change the administrator password.
High: access to the web page requires a password.
Medium: access to the web page is permied for any user, and data can be read by any user, but changes
to the device configuraon or files require a password.
Off: full access is permied for all users; no password is required.
By default, security access is set to "Off", and the administrator password is set to "admin". To change the
security level or password, open the web interface and go to the Device window, Security tab. Use the device
Reset buon to restore security sengs to factory default values.
Restoring factory default sengs
To restore network configuraon and security sengs to the factory default values, use a paper clip to press
the CONFIG RESET buon. When pressed, the default network and security sengs are wrien to the device
and the WebDAQ is rebooted.
Factory default sengs
Parameter Specificaon
IP address 192.168.0.101
subnet mask 255.255.255.0
Gateway 192.168.0.1
DHCP seng DHCP + link-local enabled
Security level Off
Password for the admin
account
admin (case-sensive)
Password for the share
account
share (case-sensive)
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).
The network sengs, security level, user account passwords and device name can be changed with the
WebDAQ web interface.
When factory defaults are restored, any shared folders or mapped drives are reset.
Contents
WebDAQ 504 User's Guide
page 8

Funconal Details
Front panel components
Figure 3. Front panel
1 Screw terminal 2 BNC connectors
Screw terminal
Connect up to four digital I/O lines (DIO0 to DI03) to the detachable screw terminal.
Figure 4. Screw terminal pinout
The digital ground (GND) terminals provide a common ground for the digital bits.
Digital connecons
The digital I/O lines are electrically isolated from the analog circuits. Each bit is individually configurable for
input or output, and features Schmi trigger inputs and open drain outputs. All DIO channels are pulled high to
5 V.
Any digital bit can be configured with the web interface as a trigger to start or stop an acquision. Any digital
bit can also be configured to trigger an alarm, and be driven high or low when an alarm occurs.
BNC connectors
Connect up to four analog inputs to the BNC connectors (AI0+/AI0– to AI3+/AI3–). All analog inputs are
simultaneously sampled at rates of up to 51.2 kS/s per channel.
Figure 5. BNC connector pinout
The center pin of the connector (AI+) provides the DC excitaon (when enabled) and posive input signal
connecon. The shell of the connector (AI–) provides the excitaon return path and AC ground reference
Use the web interface to individually configure each input for voltage or Integrated Electronic Piezoelectric
(IEPE) sensor measurements. IEPE sensor types include acceleraon, sound pressure, velocity, and force.
Voltage channels can be configured for AC or DC coupling. IEPE channels are automacally configured for AC
coupling. An internal excitaon source current is automacally enabled for IEPE sensor types.
WebDAQ 504 User's Guide
page 9

Analog signal connecons
You can connect ground-referenced or floang signal sources to the WebDAQ 504. Use a floang connecon to
minimize ground noise. If you make a ground-referenced connecon between the signal source and the
WebDAQ 504, make sure the voltage on the AI– shell is in the common-mode range to ensure proper
operaon. The AI- shell is protected against accidental contact with overvoltages within the overvoltage
protecon range. Refer to the Specificaons chapter for more informaon about operang voltages and
overvoltage protecon. Figure 6 shows a diagram for connecng a grounded signal source to the WebDAQ 504.
Figure 6. Connecng a grounded IEPE sensor
Figure 7 shows a diagram for connecng a floang signal source to the WebDAQ 504.
Figure 7. Connecng a floang IEPE sensor
Rear panel components
Figure 8. Rear panel
1 External power
connector
4 LED indicators (4) 7 Ethernet connector
2 Power buon 5 SD card slot 8 Ground connector
3 Funcon buon 6 Factory reset buon
(recessed)
9 USB connectors (2)
External power connector
Connect the external AC adapter that shipped with the device to the connector labeled EXT PWR on the rear
panel. Click here to jump to the power specificaons.
If using a different power supply than what was shipped with the hardware, ensure that the supply has a
posive center pin.
WebDAQ 504 User's Guide
page 10

Power buon
The buon labeled POWER turns the WebDAQ device on and off. WebDAQ hardware is designed with a 2-pin
jumper (W1) that users can remove to connuously power the device. The behavior of the POWER buon
when jumper W1 is installed or removed is listed in the following table.
Jumper W1 installed (factory default seng) Jumper W1 removed
When the device is off, press the POWER buon
briefly to turn the device on.
The device is always on as long as the power
adapter is connected and receiving power
(Power-On Mode).
When the device is on, press the POWER buon
for approximately 1 second to shut down the
operang system and WebDAQ hardware;
release the buon when the POWER LED blinks
yellow.
The operang system automacally powers off
the device at the end of the shutdown
procedure.
Press and hold the POWER buon for
approximately 4 seconds to force the device to
power off. Any unsaved changes may be lost
when powering down using this method.
Press for approximately 1 second to reboot the
device; release the buon when the POWER LED
blinks yellow.
Refer to Power-On Mode for the procedure to remove jumper W1 and enable Power-On mode.
The WebDAQ device can also be restarted or shut down using the web interface; refer to the WebDAQ
help for details.
Funcon buon
The buon labeled FUNC has two funcons; it can be used to eject external media or to start/stop an
acquision.
Eject external media (default): Pressing the buon unmounts all removable media so they can be safely
removed from the device.
Start or stop an acquision (requires configuraon with the web interface): When configured, pressing
this buon starts an acquision, or stops an acquision that is currently running.
Use the web interface to safely unmount removable media, when present.
When removable media is plugged into the WebDAQ, the operang system opens it for wring. To safely
remove the media, you must unmount it first.
When a job is configured to log data to external media, pressing FUNC while the job is running will not eject the
media.
The MEDIA LED is steady green when all media is unmounted and safe to remove, and off when all media is
removed.
WebDAQ 504 User's Guide
page 11

LED status indicators
The WebDAQ has four LEDs on the rear panel that indicate the status of power and host communicaons. The
following table defines the LED states during normal operaon.
LED states – normal operang mode
Label State Descripon
1: POWER Steady yellow Device is boong up
Steady green Device boot is successful.
Blinking
yellow
Device is shung down.
Off Device is off.
2: STATUS Blinking
yellow
Device is configuring hardware.
Steady green Hardware configuraon is complete.
Flashing
green
100 ms on/2s
off)
Waing for a scheduled start condion to be met.
Blinking
heartbeat
Scheduled start condion is met; waing for job start condion to be met.
Blinking
green
Data is being acquired (job start condion is met).
Off No error detected.
3: ERROR Blinking
yellow
Error condion is detected. This LED blinks even when the soware is
configured to ignore the error.
Error state is cleared when the next schedule starts.
Off No error detected.
4: MEDIA Blinking
yellow
A job is configured to log to external media, but the job hasn't started yet;
pushbuon will not let you eject media.
Steady yellow External media is inserted into the SD card slot or USB storage port.
Blinking
green
Currently logging to an external SD card or USB storage device.
Steady green Media has been made safe for removal using the funcon buon, but has
not been removed.
WebDAQ 504 User's Guide
page 12

WebDAQ LEDs behave differently when soware is updated on the device. The following table defines the LED
states during a soware update.
LED states – soware update mode
LED State Descripon
All LEDs Solid yellow Soware update is starng
POWER Blinking
yellow
Soware update is running
STATUS Blinking
green
Update file is located; device is being updated
Blinking
yellow
Update file cannot be located; insert media with update file
ERROR Blinking
green
Update is successful; device will reboot in approximately 5 seconds
Blinking
yellow
Update failed; user must retry
Refer to Updang WebDAQ firmware for more informaon about WebDAQ firmware.
SD card slot
The SD slot accepts SD (Secure Digital), SDHC, SDXC, MMC, and TransFlash memory cards. Memory cards can be
ejected using the web interface or the hardware FUNC buon, unless the buon is configured to start/stop an
acquision.
When removable media is plugged into the WebDAQ, the operang system opens it for wring. Use the FUNC
buon or web interface to unmount the SD card before removing.
Acquiring data at high speeds can generate large file sizes
If you expect to acquire a large amount of data to a single file when logging to external media, do not
use media formaed with the FAT32 file system. FAT32 is limited to a 4 GB maximum file size. If the log
file on FAT32 media grows beyond that size, a "File too large" error is returned and the acquision stops.
Before starng a logging session of this type, reformat the media using a different file system such as
NTFS. Refer to the Frequently Asked Quesons help topic for more informaon about file systems.
Factory reset buon
The recessed buon labeled CONFIG RESET restores factory default sengs. When pressed, the default sengs
are wrien to the device and the WebDAQ is rebooted. Refer to the Restore factory default sengs secon for
a list of the default sengs that are restored.
Ethernet connector
The WebDAQ has one 10 Base-T/100 Base-TX, auto-negoaon, high-speed communicaon port. The port
connector is an RJ-45, eight-posion connector. The Ethernet port accepts shielded or unshielded twisted pair
cable. The maximum communicaon distance without using a repeater is 100 m (328 ).
Ground connector
The WebDAQ ships with a ground screw in the connector labeled #6-32. To ground the WebDAQ chassis, aach
a ring lug to a 14 AWG (1.6 mm) wire. Connect the ring lug to the grounding screw on the WebDAQ rear panel.
Aach the other end to a safety ground.
WebDAQ 504 User's Guide
page 13

USB connectors
The two high-speed USB ports can be used for connecons to a mass storage device and approved WiFi
adapter.
When removable media is plugged into the WebDAQ, the operang system opens it for wring. Use the FUNC
buon or web interface to unmount the USB device before removing.
Use a self-powered hub when external media requires higher current
USB-powered hard drives may use an excessive amount of current during operaon. The WebDAQ
device could shut down or experience other errors if the power requirements of a connected device
exceed the power available. Use a self-powered hub if the current requirement of external media
exceeds 500 mA.
We recommend that you connect USB-powered hard drives before powering up the WebDAQ.
Acquiring data at high speeds can generate large file sizes
If you expect to acquire a large amount of data to a single file when logging to external media, do not
use media formaed with the FAT32 file system. FAT32 is limited to a 4 GB maximum file size. If the log
file on FAT32 media grows beyond that size, a "File too large" error is returned and the acquision stops.
Before starng a logging session of this type, reformat the media using a different file system such as
NTFS. Refer to the Frequently Asked Quesons help topic for more informaon about file systems.
Analog input circuitry
The analog input channels are referenced to chassis ground through a 50 Ω resistor. To minimize ground noise,
make sure the chassis ground is connected to earth ground. The input signal on each channel is buffered,
condioned, and then sampled by a 24-bit Delta-Sigma ADC.
Figure 9. Input Circuitry for One Channel
Overvoltage protecon
WebDAQ 504 provides 30 V overvoltage protecon for each channel.
AC/DC coupling
Use the web interface to configure voltage channels for AC or DC coupling. Configure for DC if the signal has no
offset voltage or if the DC content of the acquired signal is not important.
AC coupling is automacally enabled for IEPE channels to remove any DC offset from the measurement.
Common-mode bias current
The WebDAQ 504 uses common-mode bias current to bias the current-liming diodes when IEPE current is
turned off. When the WebDAQ 504 is using grounded signal sources, the current causes an error that is
dependent on the AI– lead impedance, and is approximately 50 ppm of range and 15 ppm of reading per Ω of
AI– impedance. The common-mode bias current causes an error only with grounded sources and is not an issue
with floang signal sources. For best accuracy, use a floang connecon or use low-impedance leads when
connecng grounded signal sources; refer to the connecon diagram shown in Figure 10.
WebDAQ 504 User's Guide
page 14

Figure 10. Measurement Error Introduced by Common-Mode Bias Current
Data rates
The frequency of the master mebase (fM) controls the data rate (fs) of the WebDAQ 504. The internal master
mebase frequency on the WebDAQ 504 is 13.1072 MHz. The data rates available on the WebDAQ 504 can be
calculated with the following equaon: fs = (fM ÷ 256)/n , where n is any integer from 1 to 31. The data rate
must remain within the appropriate data rate range. Using the internal master mebase of 13.1072 MHz results
in data rates of 51.2 kS/s, 25.6 kS/s, 17.067 kS/s, and so on, down to 1.652 kS/s, depending on the value of n.
An-aliasing filters
The WebDAQ 504 uses a combinaon of analog and digital filtering to provide an accurate representaon of in-
band signals while rejecng out-of-band signals. The filters discriminate between signals based on the
frequency range, or bandwidth, of the signal. The three important bandwidths to consider are the passband,
the stopband, and the alias-free bandwidth.
The WebDAQ 504 represents signals within the passband, as quanfied primarily by passband flatness and
phase nonlinearity. All signals that appear in the alias-free bandwidth are either unaliased signals or signals that
have been filtered by at least the amount of the stopband rejecon.
Passband
The signals within the passband have frequency-dependent gain or aenuaon. The small amount of variaon
in gain with respect to frequency is called the passband flatness. Digital filters adjust the frequency range of the
passband to match the data rate, so the amount of gain or aenuaon at a given frequency depends on the
data rate. Figure 11 shows typical passband response for the WebDAQ 504.
Figure 11. Typical Passband Response
WebDAQ 504 User's Guide
page 15

Figure 12 shows the passband at one data rate.
Figure 12. AC cutoff frequency response
Stopband
The filter significantly aenuates all signals above the stopband frequency. The primary goal of the filter is to
prevent aliasing. Therefore, the stopband frequency scales precisely with the data rate. The stopband rejecon
is the minimum amount of aenuaon applied by the filter to all signals with frequencies within the stopband.
Alias-free bandwidth
Any signal that appears in the alias-free bandwidth of the WebDAQ 504 is not an aliased arfact of signals at a
higher frequency. The alias-free bandwidth is defined by the ability of the filter to reject frequencies above the
stopband frequency, and it is equal to the data rate minus the stopband frequency.
Logging data
You can log up to 3 GB of data to internal WebDAQ storage. To generate larger data files, log data to external
media with a storage capacity suitable for the acquision. USB drives and SD cards are available in different file
formats, and OS support for each format varies. WebDAQ supports FAT32, exFAT, ext2/3/4, NTFS file systems.
When generang large data files with Windows or Mac, or transferring files between operang systems, we
recommend using external media formaed with the exFAT file system, such as an SDXC memory card. When
running Linux, use external media formaed with the ex2/ex3/ex4 file system. Refer to the WebDAQ help FAQ
for more informaon about file formats.
File too large error
If you generate data that exceeds the capacity of the selected storage locaon, a "File too large" error is
returned and the acquision stops. To avoid interrupons, select a storage locaon with a large capacity.
WebDAQ 504 User's Guide
page 16

Power-On Mode
WebDAQ Series hardware can be configured to start automacally when power is applied, instead of requiring
users to press the POWER buon. This is useful if the WebDAQ is operang in a remote locaon and a power
loss occurs. This "power-on mode" is enabled by removing a 2-pin jumper (labeled W1) from the WebDAQ
circuit board.
When jumper W1 is removed, the device does not shutdown completely unless the power adapter is
unplugged from the device or power source.
Perform the procedure below to remove jumper W1 from the WebDAQ circuit board and enable power-on
mode.
Cauon! The discharge of stac electricity can damage some electronic components. Before removing
the WebDAQ device from its housing, ground yourself using a wrist strap or touch the computer chassis
or other grounded object to eliminate any stored stac charge.
1. Power down the WebDAQ device and disconnect the power supply.
2. On the rear panel, remove the Ethernet cable, power cable, SD card, and any USB devices.
3. Remove the #6-32 ground screw.
4. Remove the nut and washer from the EXT PWR connector.
5. Remove the two front panel bezel screws and remove the front bezel.
6. Slide out the circuit board with the front panel intact.
7. Remove jumper W1 from the specified locaon shown below.
8. Slide the circuit board back into the enclosure.
9. Aach the front bezel and secure with the two bezel screws removed in step 5.
10. Secure the power connector with the nut and washer (removed in step 4) to the power connector, and
aach the ground screw, Ethernet and power cables, and any USB devices.
To automacally run a schedule when the WebDAQ powers up, enable the "Automacally start schedule on
system startup" opon on the Schedule Sengs dialog box of the web interface. If a power cycle occurs, the
schedule will restart from the beginning, regardless of which job was running when the power was lost. In
order to retain the data from each schedule start, make sure to set the logging opon for each job to "Append
Date/Time to File Name" so that each run aer power loss creates a new data file rather than overwring the
original file. Refer to the WebDAQ help for details about how to configure schedule and logging opons.
WebDAQ 504 User's Guide
page 17

Enabling power-on mode with a complex or date/me triggered schedule
When running a complex or date/me-triggered schedule with both power-on mode and auto start
schedule enabled, be aware that the schedule may not run automacally aer a power cycle if the date
or me trigger is no longer valid. In this case, the user may sll access the WebDAQ remotely to modify
the start sengs.
Replacing the baery
A buon cell lithium baery provides the me reference for WebDAQ hardware when the device is powered
off. The average lifespan of the baery is approximately 10 years.
Cauon! The discharge of stac electricity can damage some electronic components. Before removing
the WebDAQ from its housing, ground yourself using a wrist strap or touch the computer chassis or
other grounded object to eliminate any stored stac charge.
1. Power down the WebDAQ device and disconnect the power supply.
2. On the rear panel, remove the Ethernet cable, power cable, SD card, and any USB devices.
3. Remove the #6-32 ground screw.
4. Remove the nut and washer from the EXT PWR connector.
5. Remove the two front panel bezel screws and remove the front bezel.
6. Slide out the circuit board with the front panel intact.
7. Remove the baery by sliding it forward toward the slot, and replace with a 3 V buon cell baery – type
BR1225, CR1225 or similar.
8. Slide the circuit board back into the enclosure.
9. Aach the front bezel and secure with the two bezel screws removed in step 5.
10. Secure the power connector with the nut and washer removed in step 4, to the power connector, aach the
ground screw, Ethernet and power cables, and any USB devices.
Set the device system clock from the Device window, Device Info tab on the web interface.
Updang WebDAQ firmware
Device firmware is bundled with the operang system, web server, and documentaon in a soware update
(*.swu) file. Firmware updates are posted on the Measurement Compung Firmware Updates page and are
available for download.
Use the web interface to install the *.swu update file. Open a browser window and enter hp://webdaq-
xxxxxx.local/Help, where xxxxxx is the last 6 digits of the MAC address – see the label on the boom of the
enclosure. Refer to the "Updang WebDAQ Firmware" help topic or FAQ for instrucons.
Calibrang the hardware
The Measurement Compung Manufacturing Test department performs the inial factory calibraon. Return
the device to Measurement Compung Corporaon when calibraon is required. The recommended calibraon
interval is one year.
Contents
WebDAQ 504 User's Guide
page 18

Specificaons
All specificaons are subject to change without noce.
Analog input
Table 1. Analog input specificaons
Parameter Condion Specificaon
Number of
channels
4 analog input channels
ADC resoluon 24 bits
Type of ADC Delta-Sigma (with analog prefiltering)
Sampling mode Simultaneous
Internal master
mebase (fM)
Frequency 13.1072 MHz
Accuracy ±50 ppm max
Data rate range (fs) 1.652 kS/s min
51.2 kS/s max
Data rates (fs) (fM ÷ 256)/n, where n is any integer from 1 to 31
Input coupling AC/DC; soware-selectable
AC cutoff
frequency
–3 dB 0.5 Hz
–0.1 dB 4.6 Hz max
Input range ±5 V
AC voltage full-
scale range
±5 Vpk min
±5.1 Vpk typ
±5.2 Vpk max
Common-mode
voltage range
AI– to earth
ground
±2 V max
IEPE excitaon
current;
soware-selectable
on/off
2.0 mA min
2.1 mA typ
Power-on glitch 90 μA for 10 μs
IEPE compliance
voltage
(Note 1)
19 V max
Overvoltage
protecon, with
respect to chassis
ground
Signal source
connected to AI+
and AI–
±30 V
Low-impedance
source
connected to AI+
and AI–
–6 V to 30 V
Input delay (40 + 5/512)/fs + 2.6 μs
Gain dri 0.14 mdB/°C (16 ppm/°C) typ
0.45 mdB/°C (52 ppm/°C) max
Offset dri 19.2 μV/°C typ
118 μV/°C max
Channel-to-channel Phase (fin in kHz) fin × 0.045° + 0.04 max
WebDAQ 504 User's Guide
page 19

matching Gain 0.01 dB typ
0.04 dB max
Passband Frequency 0.45 × fs
Flatness (fs = 51.2
kS/s)
±40 mdB (pk-to-pk max)
Phase nonlinearity fs = 51.2 kS/s ±0.45° max
Stopband Frequency 0.55 × fs
Rejecon 100 dB
Alias-free
bandwidth
0.45 × fs
Oversample rate 64 × fs
Crosstalk 1 kHz –110 dB
CMRR fin ≤ 1 kHz 40 dB min
47 dB typ
SFDR fin = 1 kHz, –60
dBFS
120 dB
Input impedance Differenal 305 kΩ
AI– (shield) to
chassis ground
50 Ω
Note 1: If you are using an IEPE sensor, use this equaon to make sure your configuraon meets the IEPE
compliance voltage range:
(Vcommon-mode + Vbias ± Vfull-scale) must be 0 to 19, where
Vcommon-mode is the common-mode voltage applied to the WebDAQ 504.
Vbias is the bias voltage of the IEPE sensor.
Vfull-scale is the full-scale voltage of the IEPE sensor.
Table 2. Measurement accuracy specificaons
Measurement
Condions
Percent of Reading
(Gain Error)
Percent of Range
(Offset Error) Note 2
Calibrated Max (0
°C to
50 °C)
±0.34% (±0.03 dB) ±0.14% (±7.1 mV)
Typ (25
°C
±5 °C)
±0.07% (±0.006 dB) ±0.01% (±0.5mV)
Note 2: Range = 5.1 Vpk.
Table 3. Idle channel and noise density specificaons
Idle Channel 51.2 kS/s 25.6 kS/s 2.048 kS/s
Noise 97 dBFS 99 dBFS 103 dBFS
50 µVrms 40 µVrms 25 µVrms
Noise density 310 nV/√Hz 350 nV/√Hz 780 nV/√Hz
WebDAQ 504 User's Guide
page 20