profibus cp342-5 to et200s

Hello aante;

The best example I know to set a CP 342-5 as a DP master is found in the following FAQ:

What should you watch out for when configuring a CP342-5 as DP master?

It is important you note that the CP 342-5 must use special functions “DP-SEND” (FC1) and “DP_RECV” (FC2) to exchange data between the CPU and the CP over the backplane.

The FAQ explains step-by-step the choice of parameters you will need to setup, such as the LADDR (which must be written as a hexadecimal value: w#16#100, if the decimal address of the CP is 256), and the SEND and RECV parameters, ANY pointers that must cover the total data area up to the last address used by the Profibus slaves.

These last parameters seem to be the most problematic for beginners, see the example extracted from the FAQ for clarifications:

Note
The highest configured I/O address of a DP slave + 1 gives the length of the data area that is specified for the "SEND" and "RECV" parameters via the pointer.

Example
You have a DP slave (ET200M with 16 DI and 16 DO, for example) whose Q addresses occupy the area 200 to 201. In this case you specify a data area of 202 bytes on the pointer (P#DB88.DBX13.0 BYTE 202, for example), even if only 2 bytes are to be transferred to the slave.

Hope this helps,
Daniel Chartier