I know that Simatic-S7-400 supports profibus-DP, but how can a PLC communicate with a powermeter who supports modbus protocol......

 

If Siemens is the flavor of choice, then take a look at the S7-226. It is inexpensive and Siemens has a free driver for Modbus RTU that uses one of the two serial ports. The other port can be used for MPI or PPI. If you wish to go to the expense of Profibus to communicate out, then they have a S7-200 module for that as well. Many ways to get Modbus to AB, Modbus Plus or even encapsulate it in TCP/IP. My only concern would be if the powermeter follows the Modbus RTU protocol to the letter.

 

SIEMENS S7-400 can be used to be connected to the Modbus RTU protocol. This is done through the following combination: 1) For S7-400 CPU: CP441-2 + loadable drivers (either Modbus Master or Slave with RTU format) 2) For S7-300 CPU: PC341 + loadable drivers (either Modbus Master or Slave with RTU format) 3) For S7-200: The method as described by MH Truitt. Shahid Chaudhry System Integrator SIEMENS I&S ITPS, Pakistan <[email protected]>

 

Dear Tolga, You can use CP441 of S7-400 for a p-p connection or if you want to connect that device to Profibus, you can use a Modbus/Profibus converter like the one you can find in www.hilscher.com P.S. Please tell my best regards to Prof. Celtekligil. Hakan Ozevin

 

ok!!!! S7-200 works then . but what about S7-400. Is possible with S7-400 as well........