Xitron supports a 4 channel USB relay card for the purpose of switching things on and off.  It was envisioned to enable printer manufacturers to turn on and off paper transport systems, such as conveyor belts or paper feeders.

We have two levels of support for this.

1.  a stand alone application which allows for manual toggling of the channels on the card.

2.  automated control from the Navigator DFE.   Navigator DFE has a "transport layer" for starting things you may wish to start at the same time as the printhead is uncapped.  This "transport layer" recognizes when a printhead is uncapped and the buffers are ready to print.  It can send on/off commands to the relay card.

In either case, the card has helpful LED lights to indicate when each switch is on.

This document discusses the stand alone application.  The DFE support is forthcoming for Memjet Duraflex, but is as yet unreleased.  When it is released, configuring the DFE for automated use of the card will be documented here.  For now, we have documented the stand alone application.  The stand alone application and card are released and supported now.

Getting it running for the first time

RelayController.exe needs to be installed on a computer that already has Navigator installed on it. 

The path location of your installation for RelayController is not important.  You can put it where you want as long as it can find Navigator.  Upon the occasion of the first run of the application it will ask you to show it the path to Navigator Server.  It will be something like c:/navigator/navigator usually.

If the software asks you for a port number for your card; enter it.  

 If you don't know it, check Windows Device Manager.  In this case, the correct entry is "3".

Subsequent uses of the application will pop this dialog box up at start up time.  If there is already an number entry you can just dismiss the dialog by hitting <enter> or clicking OK.


Upon running the application for the first time it may ask for the path to your Navigator installation.

This is usually c:/Navigator/Navigator.  You may have chosen a different path.

After these initial dialog boxes are dismissed, "RelayController.exe" will show the window below.  The toggles represent each of the 4 channels on the card.  Toggling them on and off will open and close the relays.  LED lights on the card will show this happening.


Perhaps you wish to change the name of the application's main window to more closely reflect your actual purpose.  It could reduce confusion during a development phase.  Click the gear button on the main window.  It brings up configuration options.

Now I get this:

What if you aren't planning on using 4 channels?  Clicking the configuration button (a gear) brings up this window below.  You can see my serial port ID is 3 (which we found from looking in Windows Device Manager and noticing that it was at the port COM3).  You can also choose to limit your channels to a smaller number.

I'll switch to 1 channel.

Now the main application window looks like this:

When the application window looks like the above (with the first relay switched on) the card looks like this:

When the application window looks like this (channels A and C switched on),

The card looks like this:

You may wish to change the logo to your own company.  You may wish it to be a picture of the mechanism you are switching on and off.   Whatever you prefer, it just needs to be a PNG file.  Change it by following along below.

Then you will get this:

That is all.  A forthcoming release to the Duraflex RIP system will support automatic switching at print time.  Look for that in Autumn of 2021. Duraflex and other printers can be used with the manual application now.  Automated use is planned for Duraflex only at this time.   Other printers will be supported for automated use in the DFE upon customer request.

Appendix A.  Relay card details.

  • 4 onboard Solid State Relays with individual LEDs for status.
  • 3A Maximum Switching Current.
  • 4 TTL (3.3V)Compatible GPIOs.
  • 4 Analog Input Channels (Multiplexed with GPIOs) with 10-Bit Resolution.
  • USB interface with CDC support. 
  • Can be powered from USB or external power supply.
  • Requires a USB to USB mini cable

Appendix B.  Troubleshooting.

If you do not get correct results from the application:

-   Check that your port is correct.  If you have the port set to the wrong number (or not set at all), the application will not properly initialize.  If you cannot get the app to boot, you have a problem with the connection to the card.  

-  Check that the device shows up in Device Manager.  If not, check your cable connection.

-  Check that the board has power.  There is a small red light directly on the board, near the USB port.  When the board is getting power, this light is on.


Appendix C.  Safety.

Do not turn on heaters or dryers with this.  

Such devices require safety trips so that you cannot accidentally leave them on.  This tool is for turning things on and off that don't have the potential for disaster.  If you have a separate safety trip (e.g. something that detects temperature or movement which also must be satisfied or the connection breaks and the device turns off), then you could consider using this tool as a simple on/off.  But it would only be a part of your solution.  Using only a simple on/off tool such as this to control a dryer or heater would be a bad idea and is not supported by Xitron.  It could function as part of a system that must be satisfied by multiple conditions.