Greetings,

I’m trying to establish a connection between a CM1242-5 and a CP342-5. I’m doing the program both in TIA 14 and STEP7 5.6, this is due to the CPU 314 (314-1AE04-0AB0) available to me not existing in TIA. I’ve set up the Profibus in S7, configured FC1 and FC2 and gotten no errors.

I’ve made sure the PROFIBUS network and device ID’s match in both programs as well as the input and output addresses of the slave and the bus parameters. When I download the software in TIA to the PLC, gives me the error: 16# 02:39B3. The BUSF on the CP342-5 blinks as does the Error and DIAG lights in the CM1242-5. Any idea on what I’m doing wrong? In TIA I've tried with and without master without any change in the result. Pictures annexed to help. Anything else you need let me know.

Thanks in advance. 

Hello Joaquim;

Have a look at these documents showing how to configure a CP 342-5 as a master on Profibus-DP. They may clarify some issues:

• What should you watch out for when configuring a CP342-5 as DP master and why is it necessary to call the FC1 'DP_SEND' and FC2 'DP_RECV' functions in the user program of the CPU in order to transfer data?(Study point 5 with special attention)

https://support.industry.siemens.com/cs/af/en/view/18208090

• Using S7-300 PROFIBUS CP as DP master or DP slave CP 342-5, STEP 7 (TIA Portal)

https://support.industry.siemens.com/cs/af/en/view/109744374

Hope this helps,

Daniel Chartier

Hi Duris_I

So, turns out the CM1242 is defective. The DB size was a mishap. I’d originally tried with one byte to simplify and later was trying 16 because that’s the CP342 default, and forgot to adjust the DB. I’ve since managed to successfully communicate the CP342 with a B&R PLC, basically the same configuration for the Siemens, so, waiting for the supplier to exchange the faulty CM1242 module. Thanks for the time and the help.

Hey Daniel,

Thanks for the links. They’re quite useful. Managed to establish communication between the CP342 and a B&R PLC, using them as a guideline and helped further understand exactly what I was doing. However not much I could do about this situation since it’s the CM1242 that’s malfunctioning, just my luck with new equipment acting up :).

Thanks for your time and assistance.