Telegram

This part of the sample includes a GET request to the REST API of the Telegram Messenger (required TwinCAT version: 3.1.4024.10). With the help of the so-called "Telegram-Bot", a TwinCAT user can send messages to a specific telegram chat.

The first step of establishing a connection is the creation of the “Telegram-Bot”. To do this, the user needs a Telegram account from which they can contact the BotFather. The BotFather is a generally available account for the creation of new bots.

The BotFather returns an API token that must be used when sending requests from TwinCAT to the Telegram API. With access to this token, a HTTP client can control every function that the bot delivers. A description of the BOT API can be found here: https://core.telegram.org/bots/api

The requests are basically structured according to the following scheme:

https://api.telegram.org/bot<token>/METHOD_NAME

Sending messages from a TwinCAT PLC to a Telegram Bot can proceed as shown in the following figure. In this sample, a message from the Telegram browser version to the bot is used to request the Chat ID. To do this, a message is first written to the bot's chat via the browser or the Telegram app.

The ChatID can then be determined using the getUpdates method. For example, Postman is used here as an HTTP client:

Using this Chat ID, the sendMessage method used in the sample can then be used to send chat messages from the TwinCAT program.

PROGRAM MAIN
VAR
    // trigger command execution for Telegram samples
    bGetTelegram                    : BOOL;

    fbHttpClientTelegram            : FB_IotHttpClient :=(sHostName:='api.telegram.org',
                                    bKeepAlive:=FALSE, tConnectionTimeout:=T#10S);

    fbHttpGetTelegram               : FB_TestHTTP_Get_Telegram;
    sMessage                        : STRING(500);
END_VAR

//init client parameters at startup
IF NOT fbHttpClientTelegram.bConfigured THEN
    fbHttpClientTelegram.stTLS.sCA:='C:\TwinCAT\3.1\Config\Certificates\TelegramRoot.cer';
    fbHttpClientTelegram.nHostPort:=443;
    fbHttpClientTelegram.stTLS.bNoServerCertCheck:=FALSE;
END_IF

IF fbHttpClientTelegram.bConfigured THEN
    fbHttpGetTelegram(bSend:=bGetTelegram, fbClient:=fbHttpClientTelegram, sMessage:=sMessage);
END_IF

fbHttpClientTelegram.Execute();