Hello all,

I'm trying to connect a device with Uni Pi via Uart port (TX, RX).
I want to get information in Mervis from Arduino (some values from EC an pH sensors).
I own Unipi 1.1 hardware, use Mervis 2.3 and the protocol wanted is serial communication between Unipi 1.1 as the slave and Arduino Uno master.

I'm using a RJ11 connector from UART port on UniPi 1.1 to Arduino Uno:

• UART port GND --> Arduino GND pin
• UART port Rx --> Arduino Tx (pin 1)
• UART port Tx --> Arduino Rx (pin 0)

I've tried to open the port using:

def := 'serial:6:9600,8,N,1';
  handle := io.openport(def);
  if handle >= 0 then
  state := 1;
  end_if;

The state is updated to value "1" and then to value "2" after waiting for change of input value or timeout expiry after last values transmission - on case "1".
But in case "2" I'm getting some port statuses like 31/53/77 after attempting to open the port:

2:
if io.getportstatus(handle) = 0 then (* OperationStatus_Ok ) ( spojeni navazano *)

I tried different ports, with baud rate 9600 and second time with 115200 but I received the following errors:

• on port 1: OperationStatus_Empty = 31
• on ports 0, 2-9 and 20 - unknown error 77 (it's not in the list with possible return values)
• on ports 10-19 - OperationStatus_FileNotFound = 53.

Could you please advise on:

• how to open that port / connect the serial port
• what alternative do I have to make this communication between Arduino Uno and Uni Pi 1.1 to work
• what is OpenPort?