Hello,

You will need a CP343-1 in your S7-300 project.

6GK7343-1EX30-0XE0

But it is a spare part. 

Another possibility might be a Gateway. 

Perhaps: Anybus Communicator – PROFINET IO Device to PROFIBUS DP Device

Best regards,

Wizard

Hello;

I am sorry, your last request is not clear. What exacltly are you asking?

If you look at the following document (PN/PN coupler, Getting Started) you will see that the coupler allows transmission of data between 2 PN IO controllers, so in your case both the s7-300 and the S7-1500 must act as an IO Controller on their Profinet network. 

https://support.industry.siemens.com/cs/ca/en/view/88737127

Wizard already posted the standard solution, adding a CP 343-1 as part of the hardware of the S7-300, allowing it to act as an IO controller. For the S7-1500, this functionnality is built-in.

Since the S7-300 is an older controller, some of the harware is now only made available as a spare part, which makes it more expensive and difficult to locate. If you have trouble finding it, Wizard proposed another solution, a gateway that will allow the S7-300 to act as a Profinet IO Controller, which would allow you to connect to a PN/PN coupler.

Wizard's reply covered your inquiry very clearly, don't you think? Therefore, please clarify your last question.

Hope this helps,

Daniel Chartier