Digital Loggers


Frequently Asked Questions for DIN Relays


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Frequently Asked Questions

How can I control higher-current loads?
How can I power the DIN relay itself?
 What are the latest new features?
How do I set up network access from Windows?
How do I set up network access from a Mac? - Thanks to John McClintock
How can I access the switch from my own application or remote script?  What's the cURL API?
How do I set up a router to port forward for Internet access? -Thanks to Mike G.  Find more specific port forwarding examples here.
What are the contact ratings?
Basics: What is a relay? How can I wire it up?
What is the power dissipation?  
What are the power requirements?
What size terminals should I use?
I'd like to build a DC / solar powered IP Cam, WiFi AP, or similar DC powered system.  What components do I need?
What's the Scripting Language all about?
What's syslog?  How can I keep an event log?
How can I momentarily pulse a relay?
How do I use Wake on Lan?
What are the mounting dimensions?
What is the physical size?
How can I communicate with the serial port?
Do you have a 3-D step file or IGIS drawing?
What is the current firmware version?
Do you have a ruggedized version? Something suitable for mobile use?
What is the default IP address?
What wire should I use? How should I torque the terminals?
How do I reset to defaults
What is the default password?
On initial setup, I can't establish a Ethernet communications from a Windows PC.  Help! Do I need a crossover cable?
How can I control the switch from my own applications?   
How can I send HTTP requests?
Can you develop custom firmware for my application?
Can you develop custom hardware for my application?
Can I invert AutoPing or the web page links to use the NC contacts?
Do you support PowerMan?
Can you explain the auto-ping settings?
How can I expand EEPROM to store scripts?
What are the CRITICAL and PROTECT functions?
Where can I find the manual or spec sheet for the earlier model?
Do you have a Visual Basic.NET example program?  Thanks to Alan Holmes
Do you have a Python programming example?
Do you have a C++ programming example?
Do you have a .NET programming example?
Do you have a Java programming example?
How can I run the perl script from LabView?
Do you have a compiled Windows command line tool or a Perl example?
Do you have a Crestron control module?
Do you have a Python programming example?
Where can I find iPhone, iPad, or Android apps for Digital Loggers?

Question:        What's new in this product?

Answer:           In our second version, DIN Relay II, with serial numbers DIN22000 and higher, we added these features:

  • Relay anti-chatter protection.  Maximum relay switching frequency is limited to ~2Hz for safety and longevity.
  • Variable coil current control.  Relay holding and pull-in currents are regulated for improved efficiency.  Power consumption has been reduced by more than 40% from earlier models.
  • Watchdog supervisor.  We've added a second processor which continuously monitors the microcontroller and reboots it gracefully if necessary.
  • Increased memory. Non-volatile memory has been increased from 16kb to 256kb.  No memory expansion board is required for script storage.

In version 3.0 of  DIN Relay III, we added these features:

  • DC input voltage rating now increased to 48VDC
  • Added audio alarm-beeper
  • Added 2x16 LCD display to display status and help with setup.
  • Added internal real-time-clock with NTP and local time synchronization
  • Numerous firmware upgrades including scheduling feature , increased AutoPing speed limit and added more scripting commands.
  • Increased relay contact rating and durability
  • Added keypad for local control
  • Updated rating, testing, and specifications for higher DC input voltages
  • Eliminated the internal RJ-45 bulkhead for more reliable connection to unshielded RJ-45 plastic plugs. Connection status displayed on LCD.
  • Case color has changed, manual and box are updated, power consumption has increased slightly

In version 3.1, we added these features:

  • Added RS-232 web console for remote machine control. The +5 supply has been removed.  RS-232 has 2.5kv isolation and is brought out to three screw terminals in the upper right hand corner.
  • Added internal UVLO (Under-Voltage LockOut) for more reliable operation on battery power.  UVLO starts at 11.5V and shuts off at 10V to prevent battery damage.  This feature is designed to augment an existing UVLO/OVP charge controller in battery powered applications.  It is not a substitute for a solar/wind charge controller and doesn't guarantee proper reset of attached devices in the event that a battery is highly discharged.
  • Minor internal improvements.

Tell us what you'd like to see in the next version -

Question:        What are the contact ratings?

Answer:           All eight internal T-90 Relays have the following ratings:

Relay Contact Ratings
















Relays are RU and CE component approved, and rated at 250,000 operations MTBF at 50% load.  Case terminals are rated at 8-12A, depending on agency.  Only stranded wire of appropriate gauge should be used.  Terminals must be well torqued, but not over 10in/lbs.  It is wise to recheck torque after completing the installation.  Heavy traces and gold plating are used to minimize internal resistance between the terminals and relay contacts, typically 25m Ohms, so internal contact power dissipation is not normally a consideration. For maximum flexibility, relay contacts are unprotected.  For high current inductive switching, consider adding an external snubber circuit to extend contact life. Download contact protection information from

Question:        What are the power requirements?

Answer:  The relay dissipates an absolute maximum of 5W during switching with all relays on.   Power dissipation decreases with input voltage due to the use of an efficient switching power supply. Typical dissipation with relays off is 2W.  Although the case is well ventilated, ambient air temperature should not exceed 135F for maximum reliability.  Surges over 40V P-P may damage the internal regulator. 

The relay will shut down at input voltages below 9VDC. If you expect to encounter brown-out conditions in your application, set the Power-on-Recovery Mode on the setup page for safest operation.  To prevent oscillation, a brown-out re-latch function is also provided on the Setup page in firmware versions 1.6.9 and later. In the event of a brown-out, you may specify a time period after which the relay will attempt to re-latch the contacts. This function is disabled by default and has no effect if the relay is properly powered.   Please read the UVLO and OVP suggestions below.

Add an external MOV or other protection device across the power input terminals in noisy environments.  Power consumption below does not include any load on the +5V accessory output.  We are working hard to make this the most efficient product in its class.

DIN III Power Requirements - Idle
DC Volts I (Amps) Power (W)
8 0.250 2.00
9 0.211 1.90
10 0.191 1.91
12 0.151 1.81
14 0.129 1.81
16 0.114 1.82
18 0.101 1.82
20 0.092 1.84
22 0.082 1.80
24 0.073 1.75
26 0.061 1.59
DIN III Power Requirements - All On
DC Volts I (Amps) Power (W)
8 0.521 4.17
9 0.460 4.14
10 0.410 4.10
12 0.341 4.09
14 0.315 4.12
16 0.287 4.15
18 0.231 4.16
20 0.207 4.14
22 0.182 4.00
24 0.162 3.89
26 0.151 3.93

 The +5 output is protected by an auto-resetting polyfuse PPTC.  Overloading this output will thermally shut down the polyfuse.  Remove the load and allow 60 seconds for the fuse to reset if this occurs. 

Question:        Can I invert AutoPing or the Web Page to use NC contacts?

Answer:           For safety reasons and to prevent support issues, we have not implemented an "invert relay" function in either the web UI or AutoPing.  You can drive the relays in reverse by:

  • Setting up a script to turn a relay -on- in the event of an AutoPing failure.  For example  Line 2:  "ON 1"
  • Use the AutoPing event to trigger the script (enter the line number ie 2 of the script for that Autoping IP).

You can also use the programmable web links to start a script.  For example, a link like "CIRCUIT 1 OFF", could be lined to a script 2. ON 1, 3. END.  This inverts the "OFF" operation by closing the relay.

Question:        What are the mounting dimensions and physical size? Do you have drawings?

Answer:           Mounting holes are located on 5.308 x 1.968” centers.   Download a 2-D print here (.pdf).  Find a 3D SolidWorks drawing file here and a SolidWorks part-file here.  Here are BMP graphics of the front and back of the relay.

Question:        What terminals should I use?


Any fork or "spade tongue" terminal with a width of .270 or less and a slot of .135 or larger will work fine. Size the barrel to terminal to match your wire gauge. Be careful not to over-torque.

What is the current version of firmware?

Answer:     The current version is  on the update page  Find the revision history here, and firmware update instructions here.

What components do I need to build a remotely powered DC site using the DIN relay as a power controller?

Answer:     In addition to the load (ie. APCam, PtP link, AP, etc), you'll need a battery, some source of power, ie wind or solar, and most importantly a charge controller with OVP and UVLO features.  Over Voltage Protection is needed for reasonable battery life.  Under Voltage Lockout is needed to correctly reset attached devices as well as the DIN relay and to prevent oscillation when the battery is nearly discharged.

Question:     What is the default IP address?  How do I reset to defaults?  What is the default password?

Answer:         If you have lost the IP address or admin password, follow this procedure to reset to the default IP address of

  • Press and hold the reset button for 5 seconds to reset the network settings, user name and passwords.

The default master login is "admin" and default password is "1234".  This procedure resets the admin login and IP address and lockout, but doesn't affect outlet names and links.


Question:        Wiring and terminal information?

Answer:           Use stranded wire from 28AWG to 14AWG, or crimp and use .187-.250 spade lugs.  Ring terminals and solid (unstranded) wire should not be used.  Maximum torque recommended by the terminal manufacturer is 10in/lbs.  Excessive torque will tear the terminal from the internal PCB, cracking the solder joint and could potentially cause safety issues.

Question:     On initial setup, I can't establish a Ethernet communications from a Windows PC.  Help!

Answer:       Follow the instructions in this document.

Question:     Can you explain the auto-ping settings?


  • Enabling auto-ping

  • To enable auto-ping, the check-box to the left of the IP address must be checked, then the change button pushed. You will get a message "Autoping will automatically be enabled after 10 successful pings". This prevents rebooting units before conditions are properly established.

  • Time Between Pings
    The time between which each ping is set. The time between pings to a particular device is (Time_Between_Pings * Number_of_devices_enabled_in_the_ping_list).

  • Ping failures before reboot
    Number of times the ping has to fail (in a row) on a given device before it is power cycled.

  • Ping responses to enable autoping (0-100 pings)
    How many pings should be sucessful before enabling the autoping. This setting prevents enabling autoping on an unreliable network and rebooting equipment unnecessarily.

  • Times to attempt reboot
    Number of times to attempt power cycling before giving up and disabling auto-ping.

  • Device reboot delay
  • Length of time after a power cycle before checking for a response from the device. This allows a device or computer time to completely boot up.

    Find a more detailed description of Auto-Ping here.  Find instructions on modifying Auto-Ping behavior using scripting here.

    Question:        How can I control the switch from my own applications? 

    Answer:            Download the latest User Utility which includes PowerMan support for Linux. Your application can use HTTP communications. Here are some examples with source.

    Windows users can download a Perl interpreter to run the script version.  This script is compatible with all DLI power controllers.

    Question:        Can you develop custom firmware for my application?

    Answer:         Gladly.  We've done this for many customers.  Our programming rate is $75/hour.  After we agree on a -very specific- project description, we can send you an estimate of the time involved to code, debug and test.   

    Question:        Can you develop custom hardware for my application?

    Answer:           Gladly.  We've done this for many customers.   Please call with your requirements

    Question:        Do you support PowerMan?

    Answer:           Yes, absolutely.  The latest code is here: Download the latest User Utility here.

    Question:        How can I expand EEPROM to store scripts?

    Answer:           If you have an early DIN relay (first model with a serial number below DIN22000), you'll need expanded memory.  A 256K bit EEPROM option is available, P/N 256EE.  This is a factory installed PCB, so you'll need to send the early unit back to DLI for upgrade.  If you have the new DIN Relay II, with serial number DIN22000 or higher, 256K of non-volatile memory is already installed.

    Question:        How can I momentarily trigger (pulse) a relay?

    Answer:          Three examples:

    Just wire a capacitor in series with the circuit (assuming a DC load).  Simple.

    Click "Cycle"
    Press the existing cycle button in combination using the NC contact (instead of NO):


    Custom Script
    Name your circuit here:

    create a button that starts a script starting on line #2:

    Clicking "Open the Blinds" toggles pulses the relay per this script:.

    Try it at  admin/4321
    You can also trigger scripts remotely. More on that here.


    Question:        What's a relay?  How can I wire it up?

    Answer:           The DIN relay has dry contact FORM-C outputs.  They provide whatever output voltage you connect to them.  For example, if you connect a wire from the positive side of your 24V supply to the COM terminal, then the NO terminal will provide 24 volts when the relay is switched on, and the NC terminal will provide 24V when the relay is off.  You can operate the DIN relay on a different voltage than the relay contacts.  For example, the DIN relay could run on 12VDC, but switch 220VAC.  You can also use the relay to switch data, phone lines, or other electrical signals.  In a relay, contacts are electrically isolated from the coil.  The DIN relay controls the coil in the diagram below:

    N.O. means Normally Open
    N.C. means Normally Closed
    COM means COMmon

    Each relay is fully isolated, there is no internal connection between the relays.

    A relay schematic looks like this:
    Find relay basics here:



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    If we haven't answered your questions here, please call (408) 330-5599 or send us an email.  We'll be glad to help.

    Digital Loggers, Inc. 2005.