Adding UNICAST device to HAH livebox

Hmmm... This is really interesting idea. PLC uses Modbus protocol (like most of the PLC's i believe), so it would require lua modbus master implementation. That's not a disaster but raises 2 questions

1) will livebox survive being a modbus master? i mean processor resources, memory etc

2) if answer to (1) is not "definitely yes", maybe it's more feasible to implement modbus master as livebox native service?

But I will try to come up with some lua modbus implementation anyway

My impression that using libmodbus/freesigs is a bit heavy-weight. My current setup is

PLC that has all the lighting control logic (I am pretty comfortable with ST programming)

A number of modules that are connected to PLC via RS485 by Modbus RTU

PLC logic is self-contained, it processes all the button presses, including long clicks, double clicks, scene management etc. Functionaly the logic consists of 2 types of objects: scene (which processes inputs from buttons) and light (which is simply a boolean state). A single scene can affect multiple lights. From a xAP standpoint scene is a output and light is an input. So the only thing that I can do with a scene is to switch it on/off: switching off obviously switches off all the lights attached to the scene, switching on the scene lights up the lamps in the scene that were lit last time the scene was switched off.

Using freesig will allow me to move this logic to the HUH, but I suspect this will not give me any major benefits. First, PLC logic heavily depends on button press timings and adding additional communication step will introduce some delays that can make logic unpredictable.

So, for the modbus-xap bridge I am going to have the following

expose PLC scenes and lights as modbus TCP slave variables (1 bit for each)

on HAH side have all PLC scenes mapped to BSC endpoints as bsc.output and lights as bsc.input

on HAH side have a timer that will interrogate PLC once or twice per second to get the states of the scenes and lights. This can be done by a simple socket send/receive call.

if scene or light state is changed then bsc.event message is fired.

Another timer on HAH gets data from PLC slave every 60 seconds to produce bsc.info messages

If HAH script gets a bsc.cmd targeted to a bsc-mapped scene, it sends modbus command to update scene bit accordingly. PLC will take care of that and as a result update it's DIs and slave registers (which will result in bsc.event command as described above)

All of the above can be done by simple lua socket send/receive calls and can result in a really simple script

I will post it here as soon as it's ready

My version attached. This script simply sets single coil (modbus function 05). At the PLC side appropriate register is being checked every cycle and when it goes to 1, PLC does the job and sets this register to 0. Works flawlessly for more than a month for now

Thanks guys for a great software