Hello all.

I am trying to communicate with an external device which is ModbusTCP compatible with a S7-1200 PLC. The external device is a heater and I would like to set the setpoint temperature of the heater and periodically check the actual temperature. 

So I used the example program from Mr.Pegia.
I've set the IP address of the heater in the "My Connet DB"."my connect data".RemoteAddress.ADDR tags (192.168.0.50 - which is the Ip address of the heater) and I entered 502 to both the remote and the local ports. 

When I downloaded the PLC configuration and the PLC code to the PLC  I see the following status on the MB_Server block: 7002 - Intermediate call. Connection is being established.

This does not change. 
I tried to transfer a command to the heater through the MB_Hold_Reg, but it doesn't change anything.

The command consists of 10 characters, so I sent the following to change the setpoint of the temperature in HEX: 007B, 004D, 0000, 0000, 0000, 0008, 0009, 0008 000D,000A

Can anyone please give me some input on what to try next.

Cheers.

Aleix

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Split from Tips and sample program for MODBUS TCP.

 You should be using MB CLIENT block for your application. Not MB SERVER. MB SERVER will not server your purpose.

Thanks,

Jay

Poljo77

Hello all.

I am trying to communicate with an external device which is ModbusTCP compatible with a S7-1200 PLC. The external device is a heater and I would like to set the setpoint temperature of the heater and periodically check the actual temperature. 

So I used the example program from Mr.Pegia.
I've set the IP address of the heater in the "My Connet DB"."my connect data".RemoteAddress.ADDR tags (192.168.0.50 - which is the Ip address of the heater) and I entered 502 to both the remote and the local ports. 

When I downloaded the PLC configuration and the PLC code to the PLC  I see the following status on the MB_Server block: 7002 - Intermediate call. Connection is being established.

This does not change. 
I tried to transfer a command to the heater through the MB_Hold_Reg, but it doesn't change anything.

The command consists of 10 characters, so I sent the following to change the setpoint of the temperature in HEX: 007B, 004D, 0000, 0000, 0000, 0008, 0009, 0008 000D,000A

Can anyone please give me some input on what to try next.

Cheers.

Aleix

Hello.

Thank you for pointing me in the right direction.

But now I am puzzled how to configure the data exchange. 

I need to send the following to the heater in order to set the temperature.

00 02 00 00 00 06 FF 06 00 00 05 DC

So I made an array of 12 bytes for the MB_DATA_PTR. 

For MB_MODE I set 1 and MB_Data_Addr I set 1, but I get the following error 8381 - 

Function code is not supported.

 Do you have the Modbus register Table for the heater. You need to mention the DATA ADDR from that table which exact register you want to write. Some screenshots will be helpful.

Thanks,

Jay

Poljo77

Hello.

Thank you for pointing me in the right direction.

But now I am puzzled how to configure the data exchange. 

I need to send the following to the heater in order to set the temperature.

00 02 00 00 00 06 FF 06 00 00 05 DC

So I made an array of 12 bytes for the MB_DATA_PTR. 

For MB_MODE I set 1 and MB_Data_Addr I set 1, but I get the following error 8381 - 

Function code is not supported.

Hello.

Please see the attached photos where you can see how I configured the MB_Client block. And an example of what needs to be sent to the Heater.

I can read a maximum of 6 bytes from the heater. If I enter more than 6 at MB_DATA_LEN I get the 8383 error. 

Also If I try to write with the MB_MODE set to 1. 

Any ideas, how to configure the MB_Client so that I can read and write to the heater. 

 Why don't you try to define a Data Block(DB) for your DATA PTR so that it can store more data. Error 8383 is because you defined the length bigger than the DATA PTR size. So better you desfine a dedicated DB with larger array size so that it can read more data from slave.

Thanks,

Jay

Poljo77

Hello.

Please see the attached photos where you can see how I configured the MB_Client block. And an example of what needs to be sent to the Heater.

I can read a maximum of 6 bytes from the heater. If I enter more than 6 at MB_DATA_LEN I get the 8383 error. 

Also If I try to write with the MB_MODE set to 1. 

Any ideas, how to configure the MB_Client so that I can read and write to the heater. 

Hello,

I tried this at first. I defined an array of 12 bytes. Defined the MB_MODE to 0, MB_Data_Addr to 40001, MB_Data_Len to 6 and I get some data from the Heater.
If I put the DATA_Len to 12 I get the 8383 error.

If I try to write to the heater, I set the MB_MODE to 1, I get the same error.

 Did you tried a PC software like Modscan or Modpoll to rrad and write your heater and verify the address you want to write. If yes please make a screenshot of that as well. Just to counter check your register address you are trying to write. In the mean time like i said before, create a Datablock and define in the DATA PTR with more size and try to read all accessible data from the Movie.

Thanks,

Jay

Poljo77

Hello,

I tried this at first. I defined an array of 12 bytes. Defined the MB_MODE to 0, MB_Data_Addr to 40001, MB_Data_Len to 6 and I get some data from the Heater.
If I put the DATA_Len to 12 I get the 8383 error.

If I try to write to the heater, I set the MB_MODE to 1, I get the same error.

The error while write mode is also because you are using the same DATA PTR address registers. In that addresses only setpoint is writable and some other address are read only. So the function will execute error because it can't write all the registers defined. So you need to define only the setpoint address registered as a single byte with length 1 and try to write just that setpoint. You are getting the values but you are using the parameters in the wrong way.

Thanks,

Jay

Hi.

So If I understand you correctly I would need to have two DB's for the data. One to receive data from the heater and one to write to it. Therefore I would also need two instances of the DB client? One to read the data from the heater and one to write to it.

Cheers

A