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Home » Eclipse Projects » 4DIAC - Framework for Distributed Industrial Automation and Control » Rpi 3 - Blink experiment(The QX showing no sign of activity )
Rpi 3 - Blink experiment [message #1771353] Thu, 24 August 2017 10:22 Go to next message
Vishnu Easwaran E is currently offline Vishnu Easwaran EFriend
Messages: 3
Registered: August 2017
Junior Member
Hi everyone,

i have been learning to use 4diac and i have a Rpi setup with FORTE and a Linux system with latest 4diac. I made a simple program to switch the state of an Rpi pin taking cue from official documentation and I am attaching screen shots of all the three consoles.

After uploading the code, the console dhows a bunch of errors right away and in live monitoring I can see that QX is not at all responding. It is highly likely that i might have overlooked something important and I am seeking your help for spotting it so that I can move forward.

Good day.

Thanks in advance :)

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Re: Rpi 3 - Blink experiment [message #1771390 is a reply to message #1771353] Thu, 24 August 2017 15:08 Go to previous messageGo to next message
Alois Zoitl is currently offline Alois ZoitlFriend
Messages: 617
Registered: January 2014
Senior Member
If you get unsupported type errors it means that the respective FB has not been compiled into your FORTE instance. In our documentation there is a section on building forte for RevPi and also on how to enable IO support (needed for QX/IX). Currently this would be the sysfs module in the cmake configuration.
Re: Rpi 3 - Blink experiment [message #1771585 is a reply to message #1771390] Mon, 28 August 2017 11:04 Go to previous messageGo to next message
Vishnu Easwaran E is currently offline Vishnu Easwaran EFriend
Messages: 3
Registered: August 2017
Junior Member
Thank you Alois.

It was a silly mistake. While compiling FORTE, I overlooked the step of adding the line to select SysFs in the setup script. After recompiling it properly, the unsupported type errors are gone, leaving behind zero errors after uploading.

Something I observed later is that the FB can only write to the GPIO pins if the forte instance is running as root. Is it the right way to configure or should I change the permission, as I believe it is definitely an ownership issue. Is their a standard procedure to straighten out this ??

[Updated on: Mon, 28 August 2017 11:11]

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Re: Rpi 3 - Blink experiment [message #1771595 is a reply to message #1771585] Mon, 28 August 2017 13:10 Go to previous messageGo to next message
Alois Zoitl is currently offline Alois ZoitlFriend
Messages: 617
Registered: January 2014
Senior Member
Great that it is working for you now.

The root issue comes from the fact that FORTE uses the sysfs to access the GPIOs. In order to access this the user you are running FORTE with has to have read and write access to the "/sys/class/gpio" directory. Per default root has access to it. Furhtermore there should be a group set and if you add your user to this group you should also be able to access IOs without the need to run FORTE as root. I personally would prefer this option.
Re: Rpi 3 - Blink experiment [message #1771779 is a reply to message #1771595] Wed, 30 August 2017 10:26 Go to previous messageGo to next message
Vishnu Easwaran E is currently offline Vishnu Easwaran EFriend
Messages: 3
Registered: August 2017
Junior Member
/sys/class/gpio access says the owner as root and group as gpio, and the default user 'pi' is a member of gpio group. Also the group is given rwx rights so why is it not able to access when I run forte as pi

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Re: Rpi 3 - Blink experiment [message #1771816 is a reply to message #1771779] Wed, 30 August 2017 20:42 Go to previous message
Alois Zoitl is currently offline Alois ZoitlFriend
Messages: 617
Registered: January 2014
Senior Member
strange. How I understand permissions sunder Linux this should work.
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