Hello,

check also back side of OP where are DIP switches which need to be correctly set due your IF port cfg - serial or MPI/DP.

Update: look to your settings on PG/PC, you have same MPI address as OP - address 1, so set on PG/PC interface address 0. Your OP can have address 1 as is configured.

Thanks for fast feedback.

DIP switches are in correct position for MPI/DP communication.

As advised for PG/PC settings I change address to 0, rest leave as it was. Same result.

Hello,

pls be kind explain again your situation better. After your description I see now cfg ok (also as Wizard sugested before):

1. your PG/PC and OP have different MPI addresses.

2. your PG/PC and OP have same MPI comm speed.

In this case (I don't remember clearly) but in OP menu is some cfg option which chanell is active, disable that serial and set active only MPI/DP. On PG/PC interface set in options checkbox that means PG/PC is only one Master on network. It should be checked. If you reboot your OP you can set START or Download prj to OP. What you want to do next? You have project on OP or want download another one? In other case I'll be test classic Profibus DP cable with DP connectors on both sides, correctly wired. This is better also for MPI networks.

Hello,

your Profibus cable can be used also here, it's simply 2 wire RS-485 with termination resisiotrs on DP connectors, nothing special. Yes, not in RS-232 interface! But you've mentioned your 551 adapter so here you can attach your DP cable, on 551 it's compatible port for MPI and Profibus so I don't see problem, also used this many years. Pls, set your PG/PC 551 profile to MPI, not Auto. Set same settings as you have before.

Update: forgot to recommend then make diagnostic on PG/PC to see other nodes on network, if it's working. That DP cable I only think as replace for that original Siemens cable in case of faulty. You can then also try that cable if all will work with diagnostic. I see problem in that .Auto setting, set it to MPI.

I used .Auto setting just for a moment for diagnostic.

That might sound weird, but my OP77B works randomly. Sometimes when I reboot after "online mode message" it stuck with no visualisation loaded. Sometimes when I disconnect communication cable between OP and PLC, then reboot and starting click buttons randomly visualisation appears. Then when I connect cable again sometimes it stucks, sometimes it's communicating with PLC...

Looks like hardware problem to me.

I did change my 6ES7 901-0BF00-0AA0 cable to profibus DP cable as you suggest. First time I try to connect I got message/error: "Communication drivers can not be.." next couple attempts fail.