S7-315 2PN-DP - Profibus

[sommers9]

Dear PLC enthusiasts/professionals,

The problem
I've got a PLC like the one below.

It has 2x Profinet and 1x Profibus-DP/MPI

So apparently, the DB9 connector (VGA-like port) which is an MPI connector, can also double as an RS485/Profibus-DP port.
I'm new to Siemens PLC's and have only worked with general I/O on a Mitshubishi PLC.

I would like to set up the Profibus-DP connection, but I can only find tutorials on how to do it with an CP card.
Can someone help/enlighten me on this set-up?

What have I tried?

1. I've set up a PROFIBUS connection in the HW Config.
(see "1.png")

2. I've set up an LADDER diagram in OB1, where I attempt to send a brief acknowledgment ( 0xE5 ), but I have no idea what address I have to fill in.
When I fill in 2 (the address of the other device) I'm unable to save it.

The question(s):
1. Does the basic setup seem right? Is it possible?
2. How to find the address to fill in in the "DP-send" command block?