10/25/2012 3:36 PM | |
Joined: 1/17/2007 Last visit: 5/8/2024 Posts: 1542 Rating: (532)
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OK the S7 is master / client, but you still haven't told me if the S7 is the RTU device or the TCP device. But reading between the lines would suggest that the S7 is the TCP client device and it is talking to 20 RTU slaves. If that is the case then you need to:- 1) Get the Modbus TCP client driver software and install it onto your system. Details are available here. 2) Configure the TCP software to send out the required telegrams (polls) to slave devices to obtain the required data. Don't worry at this point that the telegrams are on TCP and the slave devices are on RTU, this will be handled via a convertor. 3) Fit a external hardware TCP to RTU convertor. Lantronix do one called a XPress-DI-IAP. Details are available here. This device basically transposes the TCP requests to equivalent RTU requests (and vice-versa with the responses). Thus it will constitute a seamless interface between the TCP and RTU sides. Thus the S7 TCP driver will believe that it is communicating with a TCP server, when in fact the data is coming from an RTU slave. This convertor is very easy to setup. However, it will need the Modbus firmware loading to it before it can be used. This firmware is available for free download from the Lantronix website. However, all this does lend the question of why you don't just fit a CP341 and use that to connect to the RTU slave devices directly (using the loadable modbus driver from Siemens). Why are you wanting to communicate to RTU devices from a TCP device? |
Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. |
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