RS-232 - MPI communication instable

Hello,

In my project I have supervision post on PC, that controls
PLC Siemens CPU314C-2DP. Communication exists but it isn't
stable.

Connection with PLC is caried out via

SIMATIC S7 PC Adapter v5.1 (from Siemens):

PC(RS-232) - PC Adapter - PLC(MPI).

I checked already all the parameters of COM1 port in
- supervision program settings
- PC settings
- PC Adapter settings (here is only one setting - baudrate).

They are the same.
On the box of PC Adapter there is LED that shows communication.
When the communication is stable it must be always ON.

In my case it alternates between ON and OFF.

Where is a problem?

I will be grate full for any help.

Pavel.

I don't have a system handy to try it on, so I can't be 100% sure, but...

If you have an operator panel of some sort connected running ProTool or some other HMI S/W, then yes, the screen will be permanently updated and the data LED will be effectively permanently on.

However, if you are using it with say Simatic Manger to transfer a program or download data, then I'm pretty sure the data LED wil only be on when data is actually being transferred. If you go into a VAT to View I/O Status or View a Block online in the editor, then once again data will be being continuously transferred and the LED will once again be permanently on.

Communication exists but it isn't stable.

Click to expand...

Maybe you could elaborate a little more. What happens ? Are there some error codes ? Or are you just worried about the flickering LED ?

Hello RMA

Thank you for answer.
At PC side I use Cimplicity HMI, where I created a POINT that is associated with particular address in PLC.
There are different options for "Update criteria" for device POINTs.
- unsolicited
- unsolicited on change
- on change
- on scan
- poll once
- poll once on change
- on demand on scan
- on demand on change

I tried all of them. The result is the same.
On the screen of Cimplicity I see alternation of
PLC cell contents and "symbol by default".

Is there any utility that permit to check the quality
of my connection?

I tried all of them. The result is the same.
On the screen of Cimplicity I see alternation of
PLC cell contents and "symbol by default".

Click to expand...

What does that mean ?
Do you see the desired values or not ?
Where do you see the "symbol by default" ?
Are you setting this up for the first time, or are there some other values that do work ?
Is the online connection to the S7 setup correctly ?
How does Cimplicity connect to S7, via OPC, or is there a "direct driver" ?

Hello Jesper,

Thank you for your attention.

It works now. I configured "PC Adapter" using SIMATIC Manager utility
and now it works.
Concerning your other questions
"Symbol by default" is symbol, associated with textbox in offline (or in absence of connection). In runtime textbox shows POINT value (if everything is OK).
Cimplicity is connected to S7 via OPC Server.

Regards.

Pavel.