I am just starting to explore MIDAS, i.e. reading the manual and trying 
some examples. For the moment I would like to make a simple frontend that 
access a portable multimeter through RS-232 port. I think this could help 
me understand how to access hardare inside MIDAS framework. Initially I've 
started from the MiniFE.c example and tried to initialize the serial port 
on run start transition and build a readout loop in the main function. I 
know that this is not a full frontend but I was just interested in getting 
some experience with the drivers available in the distribution, in this 
case RS-232. The portable multimeter is very simple in principle, one just 
has to configure the port settings and then send character 'R' and read 14 
ASCII characters from the device. Unfortunately I could not understand how 
to invoke the driver services so I changed and started again with the 
slowcont/frontend.c example. From this example and after reading the "Slow 
Control System" section in the MIDAS manual I think that all I need to do 
is to define my own equipment structure based on the multi.c class driver 
with a single input channel (and replace the null driver with the RS-232).

Here I got stuck. I see from the code source that there is a relationship 
between drivers at all levels (even bus) and the ODB but I don't yet fully 
understand how they work. Actually for a couple of days now I am in a loop 
going from class to device to bus and then back again to class drivers 
trying to see how to create my own device driver and especially how to call 
the bus driver. It could be that the framework is invoking the drivers and 
the user just has to configure things ... up to now I didn't dare to look 
at the mfe.c.

Is there a more detailed documentation about slow control and drivers then 
the MIDAS manual? What is the data flow through the three layers system for 
drivers? What is the role of the framework and what is left to the user 
choice?

Thanks