Hi, 

I am new to Modbus, may I ask where can I find relevant documentation on the setup of Modbus in the Step 7? 

Currently my setup is from S7-1200 -> Switch -> PC (HMI). I was using the S7 Comm protocol, and I was told to change to Modbus.

May I know how can I setup the Modbus connection? I notice there are Client and Server in the design.

Should I put the S7-1200 PLC as Server or Client? And what are the connections for each ports in the block?

Appreciate any reply.

Thank you.

Yours sincerely,

Eric

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Split from Modbus TCP and Modbus RTU sample application.

Yi.Hong.Lim

Hi, 

I am new to Modbus, may I ask where can I find relevant documentation on the setup of Modbus in the Step 7? 

Currently my setup is from S7-1200 -> Switch -> PC (HMI). I was using the S7 Comm protocol, and I was told to change to Modbus.

May I know how can I setup the Modbus connection? I notice there are Client and Server in the design.

Should I put the S7-1200 PLC as Server or Client? And what are the connections for each ports in the block?

Appreciate any reply.

Thank you.

Yours sincerely,

Eric

 Hello Eric,

Why do you want to go with Modbus Communication Protocol?

TIA Portal Help is good one to understand,  how  Modbus can be implement and use in S71200/S71500 PLC.

Depending on Partner type, S71200 can define as Modbus TCP server or Client.

Which type of  HMI ?

If it is Siemens then HMI will act as only Modbus TCP client.

If you want to explore yourself in Modbus World then check the forum information from SIMATIC Modbus/TCP topic.

Same forum topic, you can find Modbus TCP  sample application of S71200 PLC .

Hello DJ,

Thank you for your prompt reply. 

Yes, I wish to implement Modbus Communication Protocol.

My setup is quite simple. Just a PLC to Switch then to a HMI, the HMI is another software from ICONICS, Genesis32. There will not be any other extra PLC device included in the setup. 

Can I set my PLC as Modbus TCP Server from the Data Block? Then the PC(HMI) as Modbus TCP Client?

Thank you.

Yours sincerely,

Eric.

Hello ,

Yes,

You can define the S71200 PLC as Modbus TCP server by using Modbus Library " MB_Server " Block.

I don't know about HMI part but there you need to add modbus tcp driver in HMI and define the necessary inputs. Ex Server IP address, port number, Function code type etc.

See the attached code for S71200 as Modbus TCP server.

S71200 PLC : Modbus TCP Server, IP Address: 192.168.0.1 and port number 502

Remote (HMI) as Modbus TCP client, IP address: 192.168.0.10

same application, you can see 8 Holding Register (40001..8)  are used  for writing/reading from client. (PLC address mapping MW100 ..114)

Same application you can check with Modscan simulator software , which is acting as Modbus TCP client.

For more information about data type and function code, press F1 on MB_Server Block.

Dear DJ_1,

Thank you very much for your reply, and I appreciate that you have sent me an example to follow. May I know is there any documentation that i can refer to for better understanding?

In my case, I have a few tags in my Default Tag Table to be sent out to the HMI, may I know where can I include the content? 

I noticed that there was a post about the configuration of the MB_SERVER and MB_CLIENT

https://support.industry.siemens.com/cs/document/83130159/how-do-you-program-and-parameterize-modbus-tcp-communication-between-two-s7-1200-cpus-?dti=0&lc=en-WW

However, the version was old and the layout of the MB_SERVER / CLIENT program block is different. Do you have an updated version? 

Appreciate your help.

Thank you.

Yours sincerely,

Eric

Hi, 

May I know is there any updated documetation for the Modbus configuration example? 

Thank you.

Yours sincerely,
Lim Yi Hong

hi,

no. When you open the application description on the link you will see that it is from 01/2015

regards,

Hi,

May I know what should I set for the Modbus Server?

I only have one PLC, it will be connected as ... PLC -> Switch -> HMI.

May I know is it possible for me just to configure the s7-1200 to be the modbus server?

Thank you.

Yours sincerely,

Yi Hong

hi,

yes, this should be possible. when your S7-1200 is server, the other one is the client. and the client accesses the server.

regards,

Hi,

Thank you for your reply.

Do you have any idea how to configure the Modbus Server in Step7?

Thank you.

Yours sincerely, 

Yi Hong