Fault detection on an analog input of the FLX 3402 card


I need to detect if one of the analog inputs of the FLX 3402 expander card, is failing or the whole card. i.e. knowing that the connected sensors give correctly the data, send me a warning that the card is wrong and that specific input.

Is there any way to program that?
Using the functions get and set system can it be done?

Best regards

Hello Carlos

in the Installation Guide of the FLX 3402 Extension Card,
you can find in Section 8 the values that will result from the different Inputs.

If you create a Testrig that provides for example 10V, you can check if the Input shows the corresponding Value 65535
(You need to setup the Extension Card as explained in the Installation Manual)

You can then monitor the Value by creating a Tag for the Analog Input you are testing and taking a look on the local Webpage. (In View Mode)

You wrote you want to be notified.
Be aware:
Changes of the Value might result from small changes in the power supply.
So it might be good to add a bit of a Deadband to not be notified of every little change.

Here you can find the Basics on Alarming:

If you have setup your Tag and your Alarm and you want to be notified via e-mail or SMS (over Talk2M)
you can use this Solution Sheet:
Email & Text Messages (SMS) Relay Using Talk2M
There is no need to program in Basic for sending alarms. It can just be configured.

But if you want to trigger sending an e-mail or SMS via Basic Code the command to send an e-mail or SMS is included in the above Document.
You would just need to choose the trigger you want.

The Ewon is based on Events and in the Reference Guide you will find these Events that can be used to trigger actions
all starting with ONXXXX

You can find the Reference Guide and an example
here: https://developer.ewon.biz/content/basic-1
search for the example:
Customise the Alarm eMail (or SMS)

It will show you how to access a TagValue and send it as a String.

The Value is in a Tag. (As explained above you need to configure a Tag to get the Value of the Analog input of your Extension Card)
So you need to Access the Tag.
Get and Set System are used to change the configuration of the Flexy.


I have other question

if i want to detect to FLX 3402 or it’s working correctly, will I can do it?
My idea is to do debug at the FLX 3402, for example I want to know whatever

if the card is well connected or is giving a problem and if so send me a notice to a mqtt server
P.S. I already have the mqtt part developed


Hello Carlos,

if you check the BASIC Reference Guide you can find:
GETSYS can be used to read that information.
you can find the Parameters that can be accessed here (manually):

Interesting for you it would be if the Flexy recognizes that there is an Extension Card plugged in.
These are the Slots for the Extension-Cards:


I have a problem when I remove the card, it does not detect that it has been removed.
Using the attached code I get it to read that parameter but if I remove the card it keeps reading the same thing, that is to say when I read the Xb2PartNum register it shows me FLX3402_00/S in the basic ide console, but if I remove the card it keeps showing me the same thing.
Is there any way to update it dynamically?
Is it necessary to restart the ewon for the connection and disconnection detections to occur?
Best regards

the code is:

A$ = GETSYS INF, “Xb2PartNum”

Hello Carlos

Please do not remove or add extension cards while the Ewon is powered on.
The detection is done at boot.

You can access the Tag Quality via Basic as described here:

Otherwise it’s checking the LED of the Extension card or the Eventlogs for information.


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Ok thanks for the information

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