Hi All!

I am trying to connect a Modbus Gateway (Notifier-Honeywell) to the S7 1512 thru Modbus TCP. I am able to communicate with the gateway but with this error. Can anyone please help me solved this. Thanks.

8380 - Received Modbus frame has incorrect format or too few bytes were received.

Hi Kaulquappe,

I connected the modbus gateway to my pc and used ModScan and I got it to read the registers just fine.  Is there else anything I should check? I can't capture modbus (wireshark) because I don't have a hub at the moment.

Thanks for the reply. 

Hi Again,

I just solved it. I changed the MB_Unit_ID to 1(connection ID). I read nguyenminhdung120's post. and now the 1512 is receiving all registers. 

Hello all;

In case this subject might be interesting to others who face a similar problem, here is the thread Peter was refering to:

Read value "Holding Register" from modbus device to PLC

Created by: nguyenminhdung12061985 at: 11/25/2015

https://support.industry.siemens.com/tf/ww/en/posts/138850/

Hope this helps,

Daniel Chartier