WebDAQ 904 User's Guide
May 2020. Rev 1

Contents
About this User's Guide
Introducing the WebDAQ 904
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 areeither 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 productfor 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 ininjury. 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 ofpeople.

About this User's Guide
This user's guide describes the Measurement Compu ng WebDAQ 904 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 atwww.mccdaq.com/WebDAQ. You can also contact Measurement Compu ng Corpora on with speciﬁcques 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/wdwiﬁ.pdf
Tech support form: www.mccdaq.com/support/support_form.aspx
Email: techsupport@mccdaq.com
Phone: 508-946-5100 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 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 electricalstandards.
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 humancontact.
Hazardous loca ons: The WebDAQ is not cer ﬁed for use in hazardous loca ons.
Contents

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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 acquisi on and logging device designed for mul purpose tes ng. The WebDAQ 904 provides thefollowing features:
Measure and log data from mul ple measurement types:
Voltage (up to ± 60 V)
Current (up to ± 25 mA)
Thermocouples (50 S/s/ch)
RTD (4-wire and 3-wire)
Resistance (4-wire and 2-wire)
Bridge-based sensors (half-, quarter-, and full-bridge, and other powered load cells)

Four bidirectional, isolated DIO
Voltage and current excitation
60 VDC (AI), 15 VDC (DIO), CAT I channel-to-channel and channel-to-earth isolation
Spring terminal connectivity
10/100 Ethernet interface
Support for USB WiFi adapters for wireless connectivity
Support for USB mass storage devices and SD cards for data logging or ﬁle transfer
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 schedulingPowered 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 accessand 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 ofeach component. Open-source code is available upon request from info@mccdaq.com.

Saving large data ﬁlesIf 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 tothe Frequently Asked Ques ons help topic for more informa on about ﬁle systems.

UnpackingAs with any electronic device, you should take care while handling to avoid damage from sta celectricity. 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

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Se ng up the WebDAQ
Connec ng to a local area network
The WebDAQ 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 thisfails, 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 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 thehardware is connected to the network.
WiFi support
A er successfully conﬁguring a wired connec on, you can use the web interface to conﬁgure theWebDAQ for wireless communica on. Refer to the Conﬁguring the WebDAQ for wirelesscommunica 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 adiﬀerent 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 toauto-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.

page 5

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 freedownload – open a browser window and search for Bonjour Print Services. Zeroconf is built into popularapplica ons such as Apple ITunes® and instant messaging so ware, so your computer may alreadysupport 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.
Browser support
The latest version of Chrome, Firefox, Safari, UC Browser, or Opera recommended. Compa ble with theEdge browser version 79 and up. Not recommended for use with earlier versions of the Edge browser.
Not recommended for use with Internet Explorer.
The WebDAQ web interface is shown here.

Figure 1. WebDAQ web interface
page 6

Use the WebDAQ web interface to conﬁgure hardware and acquisi on op ons, schedule and run jobs, and toview 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 forother network scenarios.

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 anduse 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 atwww.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 toconnect 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 thecurrent network or conﬁgure the IP address type (DHCP/Link-Local or Sta c).
4. Disconnect the Ethernet cable from the LAN connec on.
Wait a few seconds, and refresh the browser window.
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, youmust 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 foraccomplishing 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).

page 7

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
IP address
Subnet mask
Gateway
DHCP se ng
Security level
Password for the admin
account
Password for the shareaccount
Device nameSpeciﬁca on
192.168.0.101
255.255.255.0
192.168.0.1
DHCP + link-local enabledOﬀadmin (case-sensi ve)
share (case-sensi ve)
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.
Shared folders and mapped drives are reset when factory defaults are restored.
Contents

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Func onal Details
Func onal block diagram
Device func ons are illustrated in the block diagram shown here.

Figure 2. Func onal block diagram

Front panel components

Figure 3. Front panel
1

Screw terminal

2

page 9Spring terminals

Screw terminal (Digital connec ons)
Connect up to four digital I/O lines (DIO0 to DI03) to the detachable screw terminal. The digital ground (GND)
terminals provide a common ground for the digital bits.

Figure 4. Screw terminal pinout
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, to trigger an
alarm and be driven high or low when an alarm or occurs, or be driven high or low when an event condi on isdetected.

Spring terminals (Analog connec ons)
Connect up to four analog inputs to the 6-posi on detachable spring terminals (CH0 to CH3).

Figure 5. Spring terminal pinout (typical)
The WebDAQ 904 supports mul ple input modes:
Voltage (up to ± 60 V)
Current (up to ± 25 mA)
Thermocouples (50 S/s/ch)
RTD (4-wire and 3-wire)
Resistance (4-wire and 2-wire)
Bridge-based sensors (half- and full-bridge, and other powered load cells)
Each channel is individually conﬁgurable for one of several modes. The following table deﬁnes the signal
connec ons for each mode.

page 10

Terminal assignments per input mode
Input mode
Voltage
Current
4-wire resistance
2-wire resistance
Thermocouple
4-wire RTD
3-wire RTD
Quarter-bridge
Half-bridge
Full-bridge

1
—
—
—
—
—
—
—
—
—
—

2
—
—
—
—
—
—
—
—
—
—

Signal terminals
3
4
—
CH+
CH+
—
EX+
CH+
CH+
—
—
CH+
EX+
CH+
EX+
—
CH+
—
EX+
CH+
EX+
CH+

5
CHCHEXCHCHEXEXCHEXEX-

6
—
—
CH—
—
CHCH—
—
CH-

Connect posi ve and nega ve signals to the CH+ and CH- terminals.
Excita on is provided via the EX+ and EX- terminals for sensors requiring excita on.
Do not connect any signals to terminals 1 and 2.

Timing modes
The WebDAQ 904 supports high-resolu on, 50 Hz rejec on, 60 Hz rejec on, and high speed ming modes.
High-resolu on ming mode op mizes maximum overall noise rejec on and provides rejec on of 50 Hz
and 60 Hz noise.
50 Hz rejec on op mizes 50 Hz noise rejec on.
60 Hz rejec on op mizes 60 Hz noise rejec on.
High speed ming mode op mizes sample rate.

page 11

Analog input circuitry
This sec on provides a circuitry diagram for each input mode.
The WebDAQ 904 is channel-to-channel isolated.
Four 24-bit analog-to-digital converters (ADCs) simultaneously sample all four analog input channels.
An excita on circuit is enabled for all input modes that require excita on.
The WebDAQ 904 reconﬁgures the signal condi oning for each measurement type.
The WebDAQ 904 provides 60 V overvoltage protec on for each channel.
The web interface provides a wiring diagram for each channel type
The Job Editor Channels tab displays a wiring diagram when you add a channel to a job. The diagram
dynamically updates according to the selected channel type.

Voltage mode

Figure 6. Voltage 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
The WebDAQ 904 computes current from the voltage that the ADC measures across an internal shunt
resistor.
The WebDAQ 904 has a ±25 mA current range.

page 12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-junc on compensa on (CJC) calcula ons.
Minimizing thermal gradients
Changes in the ambient air temperature near the front connector, or a thermocouple wire conduc ng heat
directly to terminal junc ons, can cause thermal gradients. Observe these guidelines to minimize thermal
gradients and improve the system accuracy:
Use small-gauge thermocouple wire. Smaller wire transfers less heat to or from the terminal junc on.
Run thermocouple wiring together near the spring terminal connector to maintain a consistenttemperature.
Avoid running thermocouple wires near hot or cold objects.
Minimize adjacent heat sources and air ﬂow across the terminals.
Keep the ambient temperature as stable as possible.
Increasing the thermocouple length
If you need to increase the length of your thermocouple, use the same type of TC wires to minimize theerror introduced by thermal EMFs.

4-wire resistance and RTD mode

Figure 9. 4-wire resistance and RTD circuitry
The WebDAQ 904 sources a current which varies based on the resistance of the load between the EX+
and EX- terminals. The WebDAQ 904 computes measured resistance from the resul ng voltage reading.
Lead wire resistance does not aﬀect these measurement types, because a negligible amount of current
ﬂows across the CH+ and CH- terminals due to the high input impedance of the ADC.

page 13

3-wire RTD mode

Figure 10. 3-wire RTD circuitry
The WebDAQ 904 sources a current which varies based on the resistance of the load between the EX+
and EX- terminals.
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 nega ve lead wire and the ADC uses thisvoltage

2-wire Resistance and quarter-bridge mode

Figure 11. 2-wire Resistance and quarter-bridge circuitry
The WebDAQ 904 sources a current which varies based on the resistance of the load between the CH+
and CH- terminals.
The WebDAQ 904 computes measured resistance from the resul ng voltage reading.
2-Wire Resistance and Quarter-Bridge measurement types do not compensate for lead wire resistance.

page 14

Full-bridge mode

Figure 12. Full-bridge circuitry
The ADC reads the CH+ and CH- inputs diﬀeren ally.
The internal voltage excita on sets the input range of the ADC and returns voltage readings that arepropor onal to the excita on level. The internal excita on voltage varies based on the resistance of thesensor.

Half-bridge mode

Figure 13. Half-bridge circuitry
The CH+ input is referenced to EX-.
The internal voltage excita on sets the input range of the ADC and returns voltage readings that arepropor onal to the excita on level. The internal excita on voltage varies based on the resistance of thesensor.

Rear panel components

Figure 14. Rear panel
123External power
connector
Power bu on
Func on bu on

4

LED indicators (4)7Ethernet connector

56

SD card slot
Factory reset bu on(recessed)

8
9Ground connector
USB connectors (2)page 15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 aposi ve center pin.

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 theopera 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 topower oﬀ. Any unsaved changes may be lostwhen powering down using this method.

Press for approximately 1 second to reboot thedevice; 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 themedia.
The MEDIA LED is steady green when all media is unmounted and safe to remove, and oﬀ when all media isremoved.
page 16

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
1: POWER

2: STATUS

3: ERROR

4: MEDIA

State
Steady yellow
Steady green
Blinkingyellow
Oﬀ
Blinkingyellow
Steady green
Flashing
green
100 ms on/2s
oﬀ)
Blinking
heartbeat
Blinking
green
Oﬀ
Blinkingyellow
Oﬀ
Blinkingyellow
Steady yellow
Blinking
green
Steady green

Descrip on
Device is boo ng up
Device boot is successful.
Device is shu ng down.
Device is oﬀ.
Device is conﬁguring hardware.
Hardware conﬁgura on is complete.
Wai ng for a scheduled start condi on to be met.

Scheduled start condi on is met; wai ng for job start condi on to be met.
Data is being acquired (job start condi on is met).
No error detected.
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.
No error detected.
A job is conﬁgured to log to external media, but the job hasn't started yet;pushbu on will not let you eject media.
External media is inserted into the SD card slot or USB storage port.
Currently logging to an external SD card or USB storage device.
Media has been made safe for removal using the func on bu on, but has
not been removed.

page 17

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
All LEDs
POWER
STATUS

ERROR

State
Solid yellow
Blinkingyellow
Blinking
green
Blinkingyellow
Blinking
green
Blinkingyellow

Descrip on
So ware update is star ng
So ware update is running
Update ﬁle is located; device is being updated
Update ﬁle cannot be located; insert media with update ﬁleUpdate is successful; device will reboot in approximately 5 seconds
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 beejected 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.

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 fora 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 paircable. The maximum communica on distance without using a repeater is 100 m (328 ). For CE compliance themaximum distance is 3 m (9.84 ).

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.

page 18

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.

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 ﬁleformats, 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, werecommend using external media forma ed with the exFAT ﬁle system, such as an SDXC memory card. Whenrunning 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 isreturned and the acquisi on stops. To avoid interrup ons, select a storage loca on with a large capacity.

Logging data to external media
Acquiring data at high speeds can generate large ﬁle sizes. If you expect to acquire a large amount ofdata to a single ﬁle when logging to external media, do not use media forma ed with the FAT32 ﬁlesystem. FAT32 is limited to a 4 GB maximum ﬁle size. If the log ﬁle on FAT32 media grows beyond thatsize, a "File too large" error is returned and the acquisi on stops. Before star ng a logging session ofthis 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.

page 19

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, anda 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, theschedule 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 theoriginal ﬁle. Refer to the WebDAQ help for details about how to conﬁgure schedule and logging op ons.
page 20

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 startschedule enabled, be aware that the schedule may not run automa cally a er a power cycle if the dateor 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 orother 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 lithium coin cell ba ery.
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 theground 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 areavailable for download.
Use the web interface to install the *.swu update ﬁle. Open a browser window and enter h p://webdaqxxxxxx.local/Help, where xxxxxx is the last 6 digits of the MAC address – see the label on the bo om of theenclosure. 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. Returnthe device to Measurement Compu ng Corpora on when calibra on is required. The recommended calibra oninterval is one year.
Contents

page 21

Speciﬁca ons
All speciﬁca ons are subject to change without no ce.
Typical for 0 °C to 50 °C unless otherwise speciﬁed.

Analog input
Table 1. Analog input speciﬁca ons
Parameter
Number ofchannels
ADC converter
resolu on
ADC converter type
Sampling mode
Input mode

Condi onConversion me(no channels in TC
mode)

High speed
Best 60 Hz
rejec onBest 50 Hz
rejec onHigh resolu on
High speed
Best 60 Hz
rejec onBest 50 Hz
rejec onHigh resolu on
Terminals 3
through 6, across
any combina on
Voltage mode(±60 V, ±15 V, ±4 V)
Current mode
All other modes

Conversion me(one or morechannels in TC
mode)

Overvoltage
protec on
Input impedance

Input bias current
Integral nonlinearity (INL)
Common mode
rejec on ra oSpeciﬁca on
424- bits
Delta-Sigma with analog preﬁltering
Simultaneous
Voltage
Current
Resistance (4-wire and 2-wire)
RTD (4-wire and 2-wire)
Thermocouple
Quarter-bridge
Half-bridge
Full-bridge

fin = 60 Hz

10 ms for all channels
110 ms for all channels
130 ms for all channels
500 ms for all channels
20 ms for all channels
120 ms for all channels
140 ms for all channels
510 ms for all channels
±60 V

1 MΩ
<40 Ω
>1 GΩ
<1 nA
±15 ppm>100 dB
page 22

(CMRR)
Normal mode
rejec on ra o
(NMRR)

Best 60 Hz
rejec onBest 50 Hz
rejec onHigh resolu on

90 dB at 60 Hz
80 dB at 50 Hz
65 dB at 50 Hz and 60 Hz

Input mode ranges
Table 2. Input mode range speciﬁca ons
Parameter
Voltage
Current
4-wire and 2-wireresistance
Thermocouple
4-wire and 3-wire
RTD
Quarter-bridge
Half-bridge
Full-bridge

Condi on
±60 V, ±15 V, ±4 V,±1 V, ±125 mV±25 mA
10 kΩ, 1 kΩSpeciﬁca on±60 V, ±15 V, ±4 V, ±1 V, ±125 mV±25 mA
10.5 kΩ, 1.05 kΩ

±125 mV
Pt 1000, Pt 100±125 mV
5.05 kΩ, 505 Ω

350 Ω, 120 Ω
±500 mV/V±62.5 mV/V, ±7.8
mV/V

390 Ω, 150 Ω
±500 mV/V±62.5 mV/V, ±7.8125 mV/V

Accuracy
Table 3. Accuracy speciﬁca ons
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(Note 1) resistance, 10kΩ
4-wire and 2-wire(Note 1) resistance, 1kΩ
4-wire and 3-wire RTD,
Pt 1000
4-wire and 3-wire RTD,
Pt 100Quarter-bridge, 350 Ω

Gain error
Oﬀset error(Percent of(ppm of range)
reading)
Typical 25 °C, ±5 °C, –40 to 70 °C maximum±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
±0.1, ±0.5±30, ±100±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
page 23

Quarter-bridge, 120 Ω
Half-bridge, ±500 mV/V
Full-bridge, ±62.5 mV/V
Full-bridge, ±7.8 mV/V
Cold-junc oncompensa on sensor
accuracy±0.1, ±0.5
±0.03, ±0.07±0.03, ±0.08±0.03, ±0.08±2400, ±6400±300, ±450
±300, ±1000±2200, ±8000±1 ºC, typical

Note 1. 2-wire resistance mode accuracy depends on the lead wire resistance. This table assumes 0 Ω of leadwire resistance.

Stability
Table 4. Stability speciﬁca ons
Measurement
condi ons
Voltage, ±60 V
Voltage, ±15 V
Voltage, ±4 V
Voltage, ±1 V
Voltage/Thermocouple,±125 mV
Current, ±25 mA
4-wire and 2-wireresistance, 10 kΩ
4-wire and 2-wireresistance, 1 kΩ
4-wire and 3-wire RTD,
Pt 1000
4-wire and 3-wire RTD,
Pt 100Quarter-bridge, 350 Ω
Quarter-bridge, 120 Ω
Half-bridge, ±500 mV/V
Full-bridge, ±62.5 mV/V
Full-bridge, ±7.8 mV/V

Gain dri(ppm of reading/
ºC)
±20
±20
±20
±10
±10

Oﬀset dri(ppm of range/ ºC)

±15
±15

±0.4
±3

±15

±30

±15

±6

±15

±60

±15
±15
±3
±3
±3

±120
±240
±20
±20
±20

±0.2
±0.8
±3.2
±0.2
±1.6

page 24

Input Noise
Table 5. Input noise (ppm of rangerms) speciﬁca ons
Mode, range

7.6
10.8
10.8
7.6
10.8

Conversion me
Best of 50 Hz
Best of 60 Hz
rejec onrejec on
1.3
1.3
1.9
1.9
2.7
2.7
1.3
1.3
1.9
1.9

10.8
4.1

1.9
1.3

1.9
0.8

1.0
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

5.4
5.4
3.8
5.4
30

1.0
1.0
0.5
1.0
4.7

1.0
1.0
0.5
1.0
4.7

0.7
0.7
0.2
0.8
2.3

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

Hi resolu on
0.5
0.7
1.3
0.5
1.0

Excita on level
Table 6. Half-bridge and full-bridge mode excita on level speciﬁca ons
Measurement
condi ons
Half-bridge
full-bridge

Load resistance (Ω)

Excita on (V)

700
240
350
120

2.5
2.0
2.7
2.2

Table 7. Resistance and RTD Resistance, RTD, and quarter-bridge mode excita on level speciﬁca ons
Load resistance (Ω)
120
350
1,000
10,000

Excita on (mV)
50
150
430
2,200

page 25

Digital input/output
Table 8. Digital input/output speciﬁca ons
Parameter
Digital type
Number of I/O
Conﬁgura on
Power oncondi ons
Pull-up
conﬁgura on
Input frequency
range
Input high voltage
thresholdInput low voltage
thresholdSchmi trigger
hysteresis
Input high voltage
limit
Input low voltage
limit
Output voltage
range
Output oﬀ state
leakage current
Output sinkcurrent capability
Output transistor
on-resistance(drain to source)

Speciﬁca on
CMOS (Schmi trigger) input / open drain output
One port of 4 bits
Each bit can be independently conﬁgured for input or output
Power on reset is input mode
Each bit is pulled up to 5 V with a 100 kΩ resistor
DC – 10 kHz (Note 2)
1.9 V min, 3.6 V max
2.3 V max, 1.0 V min
0.6 V min, 1.7 V max
15 V max–0.5 V absolute min
0 V recommended min
0 V to +5 V (no external pull up resistor)
0 V to +15 V max (Note 3)
10 µA max
100 mA max (con nuous) per output pin
1.6 Ω

Note 2. Applying a signal with a frequency higher than this speciﬁca on will adversely aﬀect system
performance and could cause errors.
Note 3. The external pull-up resistor is connected between the digital output bit and an external supply. Adding
an external pull-up resistor connects it in parallel with the internal 100 kΩ pull-up resistor of that par cular
digital input/output bit to the internal 5 V supply. Careful considera on should be made when considering theexternal pull-up resistor value and the resultant pull-up voltage produced at the load.

page 26

Network
Ethernet connec on
Table 9. Ethernet connec on speciﬁca ons
Parameter
Ethernet typeCommunica on
rates
Connector
Cable length
Addi onal
parameters

Speciﬁca on
100 Base-TX
10 Base-T
10/100 Mbps, auto-nego ated
RJ-45, 8 posi on
100 meters (328 feet) max
For CE compliance the max length is 3 meters (9.84 feet)
HP Auto-MDIX support

Network conﬁgura on
Table 10. Network conﬁgura on
Parameter
Network IP
conﬁgura on

Network device
nameNetwork namepublica on
User accounts

Speciﬁca on
DHCP, link-local, sta c
DHCP may be disabled by the user and a sta c IP address assigned
If DHCP is enabled but is unsuccessful at obtaining an IP address the device will fallback to link-local and request the IP address 169.254.100.100.
The name used for detec ng the device using mDNS (zero-conf). This name may bechanged using the web interface.
By mDNS
There are two built-in user accounts:
admin
share
These accounts are case-sensi ve and cannot be changed using the web interface.

page 27

Factory default se ngs
Table 11. Factory default se ngs
Parameter
Factory default IP
address
Factory default
subnet mask
Factory default
gateway
Factory default
DHCP se ng
Factory default
admin password
Factory default
share password
Factory default
device nameSpeciﬁca on
192.168.0.101
255.255.255.0
192.168.0.1
DHCP + link-local enabledadmin
Passwords are case sensi ve and can be changed using the web interface.
share
Passwords are case sensi ve and can be changed using the web interface.
webdaq-xxxxxx, where xxxxxx is the last 6 digits of the MAC address (printed on thelabel on the underside of the device).

Note 4. Shared folders and mapped drives are reset when factory defaults are restored.

Processor / Memory
Table 12. Processor / memory speciﬁca ons
Parameter
Microprocessor
MemorySpeciﬁca on
Type: Quad core Broadcom BCM2837
Speed: 1.2 GHz
RAM: 1 GB LPDDR2Flash: 4 GB eMMC (3 GB available for user data storage)

USB ports
Table 13. USB speciﬁca ons
Parameter
Number of USB
ports
USB device type
Devicecompa bility

Speciﬁca on
Two
USB 2.0 (high-speed)
USB 1.1, USB 2.0, USB 3.0

Note 5. The USB ports are provided for connec on to a mass storage device or approved WiFi adapter.

SD memory card slot
Table 14. SD card speciﬁca ons
Parameter
Memory card type
File systems
supported

Speciﬁca on
SD, SDHC, SDXC, MMC, TransFlash
FAT16, FAT32, exFAT, ext2/3/4, NTFS

page 28

LED indicators
Table 15. LED speciﬁca ons – normal opera ng mode
Label
1: POWER

2: STATUS

State
Steady yellow
Steady green
Blinking yellow
Oﬀ
Blinking yellow
Steady green
Flashing green
100 ms on, 2s oﬀ
Blinking heartbeat
Blinking green

3: ERROR

Oﬀ
Blinking yellow

4: MEDIAOﬀ
Blinking yellow
Steady yellow
Blinking green
Steady green
Oﬀ

Descrip on
Device is boo ng up.
Device boot is successful.
Device is shu ng down.
Device is oﬀ.
Device is conﬁguring hardware.
Hardware conﬁgura on is complete.
Wai ng for the schedule start condi on to be met. (Note 6)
The conﬁgured schedule start condi on is met; wai ng for job
start condi on to be met. (Note 6)
The conﬁgured job start condi on is met – the job is running.
(Note 6)
Device is oﬀ.
Error condi on is detected. LED blinks even when the so ware
is conﬁgured to ignore the error.
Error state is cleared on the next schedule start.
No error is detected, or the device is oﬀ
A job is conﬁgured to log to external media, but the job hasn't
started yet; push bu on will not let you eject media.
External media is inserted into the SD card slot or USB storage
port.
Currently logging to an external SD card or USB storage device.
Media has been made safe for removal using the FUNC bu on,
but is s ll inserted in the device.
No external media is detected, or the device is oﬀ.

Note 6. Use the WebDAQ so ware to conﬁgure start and stop se ngs for jobs and schedules.
Table 16. LED speciﬁca ons – so ware update mode
LED
All LEDs
1. POWER
2. STATUS

State
Solid yellow
Blinking yellow
Blinking green
Blinking yellow

3. ERROR

Blinking green
Blinking yellow

Descrip on
So ware update is star ng.
So ware update is running.
Update ﬁle is located; device is being updated.
Update ﬁle cannot be located; insert media containing the
update ﬁle.
Update is successful; device reboot in approximately 5 seconds.
Update failed; user must retry.

page 29

Push bu ons
Table 17. Push bu on speciﬁca ons
Component
Power bu on

Label
POWER

Descrip on
W1 jumper installed (factory default) (Note 7)
When device is oﬀ; press brieﬂy to turn the device on
When device is on:
Press for ~1 second to shuts down the device; release
the bu on when the POWER LED blinks yellow
Press and hold ~4 seconds to force the device to poweroﬀ
W1 jumper removed (Note 7):
Device will always be on if power is applied
Press for ~1 second to reboot the device; release the bu on
when the POWER LED blinks yellow

Func on bu on

FUNC

Dual func on:
Ejects, or safely unmounts, all removable media for safe
removal from the device (default)This func on is disabled when a job that uses external
media is running
The MEDIA LED is steady green when all media isunmounted but s ll inserted in the device
Starts or stops an acquisi on; requires conﬁgura on via
the web interface

Factory reset
bu on

CONFIGRESET

Restores factory default se ngs; refer to the Factory default
se ngs table for values.

Note 7. Refer to this circuit board image for the loca on of the W1 jumper.

Ground connector
Table 18. Ground connector speciﬁca ons
Component
Ground connector

Label
#6-32

Descrip on
Connector port for the #6-32 ground screw

page 30

PowerTable 19. Power speciﬁca ons
Parameter
Input voltage
Input wa age
External power
adapter
Power behavior

Condi ons
Center posi ve
p/n PS9V1AEPS230V(Note 8)W1 jumper
installed(factory default)
W1 jumper
removedBa eryBa eryreplacement

Speciﬁca on
6 VDC to 16 VDC
4 W typ, 10 W max
Phihong PSC15R-090 15 W adapter included. 9 volts, 1.67 amps,
110 VAC to 240 VAC input range required.
So power on using the momentary power bu on; device canturn its power oﬀ to shut down. Device does not resume
opera on if power is lost.
Device is always on if power is applied. Power bu on func ons
only as a reboot bu on.
One 3 V bu on cell lithium ba ery required to maintain me of
day clock when device is powered oﬀ.
Panasonic BR-1225 3V lithium coin cell ba ery or equivalent;user-replaceable.
Refer to the Replacing the Ba ery sec on for the replacement
procedure.

Note 8. If using a diﬀerent supply, ensure that it has a posi ve center pin.

Mechanical
Table 20. Mechanical speciﬁca ons
Parameter
Dimensions(L × W × H)
WeightSpeciﬁca on
158.8 × 146.1 × 38.1 mm (6.25 × 5.75 × 1.50 in.)179.4 × 146.1 × 38.1 mm (7.06 × 5.75 × 1.50 in.) includes spring connectors
680 g (1.50 lb)

Environmental
Table 21. Environmental speciﬁca ons
Parameter
Opera ng
temperature range
Storagetemperature range
Ingress protec on
Opera ng humidity
Storage humidity
Maximum al tude
Pollu on degreeSpeciﬁca on
0 °C to 50 °C–40 °C to 85 °C
IP30
10 to 90% RH, noncondensing
5% to 95% RH, noncondensing
2,000 m (6,562 )2

Note 9. WebDAQ 904 opera on is intended for indoor use only.

Safety voltages
Connect only voltages that are within the limits speciﬁed in this table.
Table 22. Safety speciﬁca ons
page 31

Parameter
Channel-to-earth
ground isola on
Channel-tochannel isola on

Condi ons
Con nuous
WithstandCon nuous
WithstandSpeciﬁca on
60 VDC for analog inputs, 15 VDC for DIO, CAT I
60 VDC, veriﬁed by a 5 second dielectric withstand test
60 VDC for analog inputs, 15 VDC for DIO, CAT I
60 VDC, veriﬁed by a 5 second dielectric withstand test

Measurement Category I is for measurements performed on circuits not directly connected to the electrical
distribu on system referred to as MAINS voltage. MAINS is a hazardous live electrical supply system thatpowers equipment. This category is for measurements of voltages from specially protected secondary circuits.
Such voltage measurements include signal levels, special equipment, limited-energy parts of equipment,
circuits powered by regulated low-voltage sources, and electronics.
Measurement Categories CAT I and CAT O are equivalent. These test and measurement circuits are for othercircuits not intended for direct connec on to the MAINS building installa ons of Measurement Categories CAT
II, CAT III, or CAT IV.
Cau on! Do not connect the WebDAQ 904 to signals or use for measurements within Measurement
Categories II, III or IV.

Signal connector
Table 23. Signal connector speciﬁca ons
Parameter
Connector types
Terminal wiring

Speciﬁca on
Four 6-posi on spring terminal connectors for analog connec ons
6-posi on screw terminal for digital connec ons
Spring terminals: 18 to 28 AWG copper conductor wire with 7 mm (0.28 in.) of
insula on stripped from the end.
Screw terminals: 14 to 30 AWG copper conductor wire with 5 to 6 mm (0.20 to0.24 in.) of insula on stripped from the end.

page 32

Spring terminals
Table 24. Spring terminal signal names
Terminal number
1
2
3
4
5
6

Signal name——
EX+/CH+ (Note 10)
CH+
EX-/CH- (Note 10)CH-

Signal descrip on
No connec on
No connec on
Posi ve excita on or input signal
Posi ve input signal
Nega ve excita on or input signal
Nega ve input signal

Note 10. Depending on the input mode, terminals 3 and 5 are either excita on signals or input signals.
Table 25. Spring terminal assignments per input mode
Input mode
Voltage
Current
4-wire resistance
2-wire resistance
Thermocouple
4-wire RTD
3-wire RTD
Quarter-bridge
Half-bridge
Full-bridge

1
—
—
—
—
—
—
—
—
—
—

2
—
—
—
—
—
—
—
—
—
—

Signal terminals
3
4
—
CH+
CH+
—
EX+
CH+
CH+
—
—
CH+
EX+
CH+
EX+
—
CH+
—
EX+
CH+
EX+
CH+

5
CHCHEXCHCHEXEXCHEXEX-

6
—
—
CH—
—
CHCH—
—
CH-

Screw terminal
Table 26. Screw terminal pinout
Terminal
#
1
2
3

Label
GND
DIO0
DIO1

Terminal
Use
Digital ground
Digital bit 0
Digital bit 1

#
4
5
6

Contents

page 33

Label
DIO2
DIO3
GND

Use
Digital bit 2
Digital bit 3
Digital groundEU Declara on of Conformity
EU Declara on of Conformity
According to ISO/IEC 17050-1:2010
Manufacturer: Measurement Compu ng Corpora on
Address: 10 Commerce Way
Norton, MA 02766
USA
Product Category: Electrical equipment for measurement, control and laboratory use.
Date and Place of Issue: May 31, 2017, Norton, Massachuse s USA
Test Report Number: EMI7018.17
Measurement Compu ng Corpora on declares under sole responsibility that the product
WebDAQ 904
is in conformity with the relevant Union Harmoniza on Legisla on and complies with the essen al
requirements of the following applicable European Direc ves:
Electromagne c Compa bility (EMC) Direc ve 2014/30/EU
RoHS Direc ve (EU) 2015/863 amending Annex II to Direc ve 2011/65/EU
Conformity is assessed in accordance to the following standards:
EMC:
Emissions:
EN 61326-1:2013 (IEC 61326-1:2012), Class A
EN 55011:2009 + A1:2010 (IEC CISPR 11:2009 + A1:2010), Group 1, Class A
Immunity:
EN 61326-1:2013 (IEC 61326-1:2012), Controlled EM Environments
EN 61000-4-2:2008 (IEC 61000-4-2:2008)
EN 61000-4-3:2010 (IEC61000-4-3:2010)
EN 61000-4-4:2012 (IEC61000-4-4:2012)
EN 61000-4-5:2014 (IEC61000-4-5:2014)
EN 61000-4-6:2013 (IEC61000-4-6:2013)
EN 61000-4-11:2004 (IEC61000-4-11:2004)
Environmental Aﬀairs:
Ar cles manufactured on or a er the Date of Issue of this Declara on of Conformity do not contain any of
the restricted substances in concentra ons/applica ons not permi ed by the RoHS Direc ve.
Carl Haapaoja, Director of Quality Assurance

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