PROFIBUS process data

The CX8031 can exchange up to 240 bytes of process data with the PROFIBUS master in the input and output direction via PROFIBUS. Various kinds of process data can be defined by means of the GSD file.

The data are transmitted by default in the Intel format. If your controller requires the data in the Motorola format they must be turned accordingly.

You can proceed in 3 possible ways here.

• Turning the data on the PLC, i.e. on the CX side, with a simple ROR command (example for ST: VarProfibus:=ROR (VarAnalog,8); (* both variables are of the type WORD*))
• Turning the data on the master side
• Turning the data in the System Manager

To do this, go to the variable that you wish to turn, select Flags and tick the option that you need. In the case of WORD variables you can only swap the LO and HI byte, in the case of DWORDs you can additionally swap the WORD.

Example: for DWORD 

(Intel format)