Serial ports on Opta

Hardware Opta
1

Hi, I'm trying to use an existing code for Arduino on Opta Wifi . Key part of this code is the use of UART to communicate to an external sensor on RS485, using a proprietary protocol (unfortunately it is NOT Modbus).

I have two problems:

  1. I don't know which of the serial ports of the microcontroller is used for RS485 interface on Opta
  2. I'm not sure if there is a way to "bypass" Opta OS and write directly on the UART in the same way I do with Serial1 or Serial2 on Arduino Mega2560.

I'm using Arduino IDE.
Thank you for your help!

2

According to the pins_arduino.h file, the RS485 port is driven by Serial2.

3

But I want RX/TX pins mapped to any of I1-I8 from Serial3 if possible. Still trying to work out if I can achieve this. Looks like Serial -> USB, Serial1->Wifi, Serial2->RS485 but no idea what Serial3 is physically wired to. The pins file states

#define SERIAL3_TX			PB_9
#define SERIAL3_RX			PH_14
#define SERIAL3_RTS			PA_15
#define SERIAL3_CTS			PB_15

Will report back if I find anything out.

4

Same question here. I wanto to make use of serial port of this PLC, not RS485 Modbus, my question would be: ¿ Can i use the serial2 to program serial comm on the arduino ide? Do i have to use a RS485-RS232 converter in order to use the UART? Please help.

5

Ive been thinking using serial libraries in serial2 and use a RS485-RS232 converter to connect to a the RS232 device. Could this do the trick?

1 Like
6

Hi @gibo_23

Have you found a solution to use any serial ports on Arduino Opta?

Thanks,
marian

7

In the OPTA WiFi documentation, I found information that the AUX connector for the expansion module has RX and TX pins. I haven't figured out how to use them yet. If anyone knows which Serial it is, please help.
From what I understand, the connections marked in red are actual connections, while those in blue are not present on the board.

I am also trying to connect a 3.3V TTL device (RX/TX) to the RS485 via a converter. I will let you know if I succeed.

schematic_aux
schematic_aux1258×740 51.2 KB

EDIT
I just discovered that AUX is Serial1 (UART 3V3), so you can read data using as simple code as follows:

void setup() {
  Serial.begin(9600);
  Serial1.begin(9600);
}

void loop() {
  if (Serial1.available() > 0) {
    char received = Serial1.read();
    Serial.print(received);
  }
}
2 Likes
8

So how did you connect rx and tx pins to it? Or how did you connect to it in general?

9

Maybe this can help. It shows the TX and TX pin is location on the Expansion Port.

image
image787×715 88.1 KB

2 Likes
10

For testing purposes, I simply soldered the wires to the AUX. I don't have any knowledge about a socket that fits this connector.