At a Glance

Let us suppose we want two PLC stations to communicate on a Fipway network. Station 1 must send the data (20 bytes located in %MW70:10) to station 2, which receives it in a table located in %MW80:10. Each PLC has a management table starting with the address %MW90.

For station 1, the word %MW93 must contain the length of the data to be sent, or 20 (10 words to be sent).

For station 2, the word %MW93 is set to 0 before the exchange, in order to see the number of characters received at the end of the exchange.

The DATA_EXCH function requires both PLCs to be programmed, one to send, the other to receive.

Illustration

The two stations are connected via a Fipway network:

Transmission Programmed in Station 1

Programming in ST:

IF RE(%I0.3.2) AND NOT %MW90.0 THEN
   (* initialization of the data to send *)
   %MW93:= 20;
   (* communication function *)
   DATA_EXCH(ADDR(’{20.2}APP’),2,%MW70:10,%MW90:4,%MW80:1);
END_IF;

Request parameters:

Parameters

Description

ADDR(‘{20.2}APP’)

  • 20 : network

  • 2 : station

  • APP: application of station 2

2

Type of communication: transmission

%MW70:10

Data to send

%MW90:4

Management table

%MW80:1

Reception zone for responses. Here, there is no data to receive, but a word must nevertheless be reserved (compulsory).

Reception Programmed in Station 2

IF RE(%I0.3.4) AND NOT %MW90.0 THEN
   (* initialization of the data to receive *)
   %MW93:= 0;
   (* communication function *)
   DATA_EXCH(ADDR(’{20.1}APP’),3,%MW70:1,%MW90:4,%MW80:10);
END_IF;

Request parameters:

Parameters

Description

ADDR(‘{20.1}APP’)

  • 20 : network

  • 1 : station

  • APP: application of station 1

3

Type of communication: reception

%MW70:1

Data to send. Here there is none, but at least one word must be reserved.

%MW90:4

Management table

%MW80:10

Reception zone: 10 words are provided from station 1.