there has been some work already done on such thing. However it has never been finished and there is also no documentation for it so I recommend using the function blocks (like PID, delays etc) that are already included in Mervis.
Hello, there is a SSCP protocol that you can read and set all variables used in your project. See downloads.unipi.technology -> Software -> Mervis -> Documentation for example in C++ and protocol specification.
It is a little bit modified ModBus protocol so the implementation is not difficult.
I think that you could connect the switchoff delay block behind the B31 as you suggest or a simple gt/lt (greater than/less then - but this will not solve the hysteresis as the B31does).
As it is written in the documentation, X is the actual temperature from a sensor, W is the setpoint when the output will become True, Xp is the hysteresis - eg if set to 5, the out will become True once the teperature goes below 90-5=95 thus the relay will not switch that frequently. Take a look at the graph on the help file….
first of all you might need to set the sleep mode to minimum because the runtime run in loops which takes some time (not event-driven system) so it is highly possible you will not be able to catch pulses that do not take much time.
There is no how-to. You would have to do it on your own. But most of them are in /var/opt/rcware /tftpboot/ and you will also need /www/ and of course the init scripts /etc/init.d/ - scripts and nginx and maybe some libraries…
By the way what is the purpose of this? We worked hard on making the system as much read-only as possible in order to keep your sd card safe... It might be easier to install your packages on the distribution that we created.