Hello @Achilleas-Kotsis,

the issue is caused by kernel-headers version mismatch because one of the kernel versions has been "stashed" by the author. Therefore, the apt versioning got a little confused by this.

Please make sure you have the latest all the related packages - kernel, headers, unipi-kernel-modules-dkms:

root@UNIPI1-sn1:/home/pi#dpkg -l *kernel*
...
ii  raspberrypi-kernel         1.20190925+1-1      armhf        Raspberry Pi bootloader
ii  raspberrypi-kernel-headers 1.20190925+1-1      armhf        Header files for the Raspberry Pi Linux kernel
ii  unipi-kernel-modules-dkms  1.36                all          UniPi Neuron/Axon kernel modules - DKMS source
...

If you upgraded kernel, reboot the system. Check the appropriate version of your headers:

root@UNIPI1-sn1:/home/pi# uname -r
4.19.75-v7+
root@UNIPI1-sn1:/home/pi# ls /usr/src/
linux-headers-4.19.75+  linux-headers-4.19.75-v7+  linux-headers-4.19.75-v7l+  unipi-1.36

Then, remove the package:

apt purge unipi-kernel-modules-dkms

And install it again

apt install unipi-kernel-modules-dkms

Have you been successful with the procedure?

Hello @cvrcejir,

this item is associated with a Modbus extension. The extension can contain "emulated" UART-Over-Modbus port with this index.

However, there is no such kind of extension currently available and therefore this value has no meaning now.

Hello @pascal37,

the issue has been caused by the old version 1.62.0 of libboost-system. Our newly deployed Mervis packages 2.2.x.x are based on the Debian Buster distro where the version 1.67.0 of the package is used. It should be fixed in the dependency list now.

Can you please do apt update and try to install the package again?

Hello @derinex,

as I do not know any details about your system, there is hard to help you. B37 is a standard PID regulator without any advanced features (such as integrator limiter - anti-windup, derivation filter nor any kind of auto-tuning). You can try the following:

1. Tune-up PID parameters - e.g. try to turn off the integration (I) and derivation(D) parts or change proportional(P) gain. As an inspiration, you can see the old well-known tuning method by Ziegler-Nichols (https://en.wikipedia.org/wiki/Ziegler–Nichols_method). Unfortunately, these methods may not be sufficient for systems with significant transport delay (which is probably your case).

2. Use a regulator with more advanced structure. But, this kind of FUPLA blocks is not a part of the current version of Mervis IDE. Therefore, you have to compose it of basic blocks (or extend the B37). This approach requires a deep knowledge of the problematic.

I am sorry, but there is probably no simple ready-to-use (or plug-and-play) solution.

Hello @matrixratrix,

the control panel is hosted by the Nginx webserver. You can simply remove the "evok" symlink from the /etc/nginx/sites-enabled/ directory. After doing this, you have to restart (or disable) the webserver to reflect this change:

sudo su
systemctl restart nginx

Hello @Vesa-Kauppinen,

it seems you do not have the unipi kernel module loaded. Can you try "lsmod | grep unipi"? If it still does not give any output, try to update unipi packages again.

Hello @Pavelf,
if I understand you, the problem with logical states synchronization occurs during the same GPIOs toggling from more than one different applications/libraries simultaneously (Evok, pigpio, FHEM, WiringPi...). The Evok always returns internally-cached values which can lead to described behaviour under certain circumstances. Also, the pigpio internally used by the Evok has been upgraded recently. I will check this more thoroughly and let you know.

Hello @stephane-clavel,

it seems you have not some kernel modules loaded. Try lsmod command - you should see unipi, at24 and i2c_dev modules loaded. If not, follow the steps below.

As the first step, try to reinstall appropriate package (assuming you have the unipi repository already sourced):

sudo su
apt-get install unipi-kernel-modules

As the second step, reboot the controller.

You can try to install unipi-kernel-modules package containing precompiled modules (while the unipi-kernel-modules-dkms package is removed automatically).

sudo su
apt-get update
apt-get install unipi-kernel-modules

Current version of the package is 1.32.1.xxxx

Hello @Dirk,
our web-services API EVOK is tested with the RPi4. It uses pigpio library internally. As you mentioned, there are no changes in the GPIOs since previous versions of RPis. Do you have internal pull-ups turned on as mentioned in the manual?

Can you please post a schematic of your circuit?