Im hacking kitchen chimney to get it connected to Modbus and then to KNX, as my whole house is KNX networked.
Im trying to use Arduino Nano between control panel and main board (10 pins).
Control board has 5 buttons, with IR receiver and 7 segment display. Motor has 5 speed, and there is timer and light control.
I post some photos here of the chips and boards to help you out.
Main board main chip is HT48Fi0E and it drives ULN2003 (G4) for more I/O.
So missing part is, how 7 segment LEDs and buttons interact with each others, as they are in same line...
(Example segment B is same line with on/off button) etc.
What exactly you want, how you want to control it.
There are some good MODBUS libraries working great.
I have used them to connect arduino uno with PLC and they are working good.
One of them is by ModbusMaster by juanB.
Making the rs485 to ttl interface is little confusing but working.
Modbus part is easy.
The problem is to get between control panel and main board.
So:
Press button in panel
-> signal arduino
-> switch coil (modbus)
-> send signal to main board (as original panel would)
And
-> main board sends 7segment signal
-> arduino reads it (gets current speed & if timer is activated (segments blink))
-> sets modbus coils/registrys as needed
-> sends same signals to panel
After that adding modbus is watering in the park (Havin 8 arduino's, 9 property devices in network with modbus/knx (arduino) gateway)
So my biggest problem is, that I have 10 wires, 1 = 5v?, 8 gnd for 7 segment display, 1 gnd for IR receiver (control panel has one). But in same lines with 7 segment display is 5 buttons, so when I press button 1, it adds something to the 1 led segment line, my first try was that maybe it just drops voltage and main board compensates that when notices (as the led dimm's when just powering them) and registers button pressed.
I know this has to be simple electornics, just cant wrap my head around it
May be the LED is only meant to respond to remote only and give you proper digits when you remote control it.
You can hack push buttons easily as it is no type.
You just have to find common point(or may be 5V ) connected to push buttons one point so once you know what is switching value (5 or 0V) for push button just connect another side of P_B point to your arduino to make arduino or control board common just join their negative points.
Nope, the 7 segment display will always show the speed of device (1, 2, 3, 4, 5).
And there is common 5v point, and button is connected to the same lines with segment display.
You can take connections out of led pins through wire and via transistor feed it to arduino so if led segments register any digit then it will be through particular pins of led segment so you can detect pattern in arduino.
