Good day to all,

Please help me in establishing data communication/exchange between two PLCs with different projects and different connections. 

PLC1 = CPU 314C-2DP (via CP343-1)  Step 7 v5.4

PLC2 = CPU 315-2PN/DP Step 7 v5.5

The two PLCs are connected to the same network through ethernet.

PLC1 is programmed by LAD, while PLC2 is through CFC (PCS7).

Is is possible to communicate the two PLCs? Do I need to make a new project with both stations present?

I'm a newbie to this one, please explain step by step on how to do it.

Thanks in advance!

Hello jomzki;

The easiest way for you to exchange data between the 2 CPUs would be to use the GET and PUT functions (FB14 and FB15)

Since GET and PUT use unilateral (single-sided) connections, I suggest you define the connections on the CPU 314C-2DP (with CP 343-1); this way it becomes the client in the network, the CPU 315-2PN/DP becomes the server. All you need in the CPU 314C-2DP configuration is the IP address of the server partner. No programming of any kind is necessary in the server.

You will find explanations and a sample program for GET and PUT in the following link:

How do you program communication blocks FB14 "GET" and FB15 "PUT" for data exchange in the S7 program of an S7-300 CPU?

https://support.industry.siemens.com/cs/ww/en/view/18610307

Note this important information for your project:

• The latest version of the FB14 "GET" and FB15 "PUT" communication blocks for data exchange by way of a CP343-1 or CP342-5 is available in the SIMATIC_NET_CP library under "CP 300 > Blocks".

Daniel Chartier

Thanks for the reply dcchartier:

Do I need to make a new project and configure the two stations?

Can I do this online, without having to stop the PLCs?

Thanks!

Hello jomzki;

You can integrate the communication  functions in the program and modify the Netpro configuration in the existing CPU 314C-2DP program.

However you will have to stop the CPU S7-314C-2DP when downloading the modified Netpro configuration, since it affects the hardware configuration of the CPU, which cannot be updated or changed in RUN.

I forgot to ask how much data you needed to transfer between the CPUs, PUT and GET are limited to 160 bytes per call. This example shows how to sequence multiple PUT and GET calls to transfer more than 160 bytes between the partners:

How do you program the function blocks FB14 "GET" and FB15 "PUT" in the S7 program of the S7-300 in order to transfer more than 160 bytes of data?

https://support.industry.siemens.com/cs/ww/en/view/49450152

Hope this helps,

Daniel Chartier

Thanks. How about the other PLC (CPU 315-2PN/DP)?

Do I need to configure its hardware/network setting? Or can I just add the necessary communications block online?

Hello jomzki;

Please read  my first answer again, or open the sample programs. No programming, no new blocks, no Netpro configuration is necessary on the S7-315-3PN/DP. It is the server in this data exchange setup, and the server requires no modification.

Hope this helps,

Daniel Chartier 

Thanks DC,

So, I can just put any DB variables in the DBs?

If I will configure this correctly, will I be now able to command and output at CPU 315, using the input/s from CPU 314?

Thanks!

Thanks for the reply Mop,

In the project, do I need to make a new project with both PLCs in it?

Because the examples does not contain any stations.

Or I can do this separately with each project?

Assuming I configured this correctly, how can I call an input from the other PLC and then command an output to the other? Sorry if I don't fully understand yet. Thanks

Hello.

There is not a need to have all in one project. The communication configuration is one sided.

Assume PLC1 and PLC2. PLC2 has the PUT and GET instructions. PLC1 is unchanged. For PLC1 it looks as if PLC2 is an HMI. PLC2 gets data from PLC1 and PLC2 puts data into PLC1.

The program specifies where the block data is and how big the block data is. For PLC1 and for PLC2. That is what the "P#" - thing is for. You can read up on "any pointer" for detailed description. It is important to note that the block size cannot be in bit sizes. Byte size or increments of it is required.

It is essential that you read the help pages on the PUT and GET for you to move forward. The win for you will be to code something and test it in actual conditions. You are welcome (IMHO) to place your test code (PLC2 only) to have it verified by some experts.

Good luck.