Hello!

I am trying to establish communication between S7 1500 and COMAP InternetBridge-NT  which is connected with COMAP InteliDrive DCU Marine controler.

I am using MB_CLIENT function for reading modbus registers over TCP/IP from COMAP. 

The IP addresses are good and port 502 is ok. I have tray red different numbers of registers and different Modbus addresses. I only need reed Holding registers (40001 ->).

I receive different STATUS:

0001 - Connection established

7003 - Connection is being terminated

7004,7005,7006,

but also receiving

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

with ERROR signal.

When i tray read registers from PC Modbus Simulator everything works ok.

Any suggestions?

Hi Duris,

When I tray to reed data with PLC from PC (Server) I receive data. So PLC program works ok i think.

I have tray read from PC as client from COMAP device an I receive errors also. So its looks like that COMAP don't send correct values. I need to see how to change sitings in COMAP IB-NT.

Thanks

A wild idea follows ->

I have had some issues with a (not named) ModbusTCP device that gave same type behavior you describe. In my case the device made available a block of data. The whole block of data had to be read from the device, not only a part of the block - even if I needed only one register.

Thanks all for advice, I will contact for device support. 

Regarding reading holding registers, it use standard registers (words, 2 byte) and should be read as one or in block. 

Every new proposal is welcome.

Hello

Did you find a sulotion?

I have exacly the same problem :/

Ive tried the support but the gave me no answer.

Im in the middle of a commissioning and its time sensative. Help is needed :)