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Lua Module at

The at module allows interaction with GSM/GPRS/3G/4G modules using AT commands. It facilitates communication with these modules for sending and receiving data.

To import it, use the following declaration:

local at = require("at1")
-- replace serial with the name defined in the configuration file

Configuration

The at module requires specific configuration to function. This configuration is defined in the agent's configuration file.

Here is an example with all possible options:

iot:
  modules:
    at:
      - name: at1 # module name
        port: /dev/ttyUSB0 # serial port
        baud: 5 # timeout
        read_timeout: 5 # timeout

Configuration Details

  • name: The name of the module. It must be unique and should not contain spaces or special characters.
  • port: The serial port to use. It must be in the format /dev/ttyUSB0 or COM3 (for Windows).
  • baud: Transmission speed (baud rate). Defaults to 9600 (e.g., 9600, 115200).
  • read_timeout: Timeout for reading data. Defaults to 5 seconds.

Lua Functions

at.send(cmd)

Sends an AT command to the configured module.

  • Parameters:

  • cmd (string): The AT command to send.

  • Return:

  • "OK" if the command was successfully sent.
  • Otherwise, returns nil and an error message: write error: <error>.
local at = require("at1")

local status, err = at.send("AT+CSQ")
if not status then
    print("Error sending AT command: " .. err)
else
    print("AT command sent successfully.")
end

at.query(cmd [, terminator])

Sends an AT command to the configured module and waits for a response.

  • Parameters:
  • cmd (string): The AT command to send.

  • terminator (string, optional): The response terminator character. Defaults to \r\n.

  • Return:

  • The response from the module as a string.
  • On error, returns nil followed by an error message.
local at = require("at1")
local response, err = at.query("AT+CSQ")
if err then
    print("Error during AT query: " .. err)
else
    print("AT response: " .. response)
end

Associated Lua Fields

  • at.name: Returns the instance name of the at module.
  • at.type: Returns the module type (here, at1).