making connection between s-300 and 417-5h with modbus

hi to all

We have a chiller package that is controlled by a s-300

we want transfer some  i/o with  tcp  modbus protocol to cpu 417-5h in dcs

please help me what am i doing?

Hello behnam ba;

Is there a particular reason you would use Modbus TCP for exchanges between S7 CPUs in your project, some client requirements possibly? It is much easier (and less costly) to use Profinet for example, a native protocol to s7 CPUs and CPs.

For Modbus TCP communications, you need to access  Ethernet on all your CPUs, either using an integrated Profinet (PN) port, or a CP 343-1 or CP 443-1.

In the following lnk you will find the Modbus TCP package licensess available for your S7-400H and S7-300:

- How do you establish a Modbus/TCP communication from a SIMATIC S7-300/S7-400 and where can you find further information?

https://support.industry.siemens.com/cs/fr/en/view/22660304

For your S7-400H station, I suggest you use the integrated PN ports of your CPUs to connect as a redundant client to your S7-300 server, you would need license "Modbus/TCP PN CPU Redundant", 6AV6676-6MB10-0AX0. 

For the s7-300, if you have an integrated PN port, installl license "Modbus/TCP CP Redundant", 6AV6676-6MB30-3AX0. If you do not, you have to add a CP 343-1 (any model should do, even a CP 343-1 LEAN) and use a license "Modbus/TCP CP", 6AV6676-6MB00-6AX0.

If you look at the bottom of the link, you will see dowload links for the software licenses that you can install in your project to test the communicaton links. The downloads are fully functional, but until the license is purchased and installed in the CPUs you will have a SF LED and a recurring error message in the diagnostic buffer and the block status (code A090), which clients do not appreciate.

- Would Modbus TCP PN CPU work without any license purchased?

https://support.industry.siemens.com/forum/fr/en/posts/would-modbus-tcp-pn-cpu-work-without-any-license-purchased-/156694/?page=0&pageSize=10

Hope this helps,

Daniel Chartier