Manage digital outputs on receiving a command string

Starting from the SendDIStatus program described in the post you quoted (The sorce code is available), I have developed a new program DIOManage that reaches the requirements.

The two sections, send string on DI change, and set DO on command receive, are now splitted in two function blocks, both written in ST (Structured text) language. A LD (Ladder) program opens the serial communication port, sets the communication mode and executes the two FBs.

I retain this solution more clear, the LD program is easy to understand and by debugging the program it’s more easy to be focused, each FB executes its own function, one FB sends the string on inputs change and the other FB manages the received command. Here the program printout and the source code.

It’s very simple to use the Ethernet to communicate instead of the serial line. The only think is need to do, it’s to change the FName in the Sysfopen function, defining TCPSKT instead of COMx.

After opening the TCP/IP connection it’s necessary to define the socket options by using the SysSktListen FB. For more information please refer to the SlimLine system IEC61131-3 programming Manual, you can download it from the download section at the bottom of the SlimLine CPU web page.

Here you can see the printout and the source code of a new program called EthDIOManage, the only differences between this and the previous is in the Communication ladder program.

How you can see this program accepts a TCP/IP connection on port 1000 (You can change the port on the SysSktListen FB). When inputs change theirs status it is sent over the TCP connection, when a command is received from the TCP connection the outputs are managed according it.

To test the program, it’s necessary simply to open a TCP/IP client connection on port 1000, to do this you can use any Telnet client for example our Toolly utility. Here a screenshot with the program test report using Toolly.