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s7-1200 TCP coms to third-party device

8/17/2010 7:46 PM	Rate (0)
ieTechSup Posts: 5 Rating: (0)	Hi we’ve been reviewing a range of low cost PLCs & the s7-1200 looks great value especially the TCP comms. Looking at the documentation it seems as the T-Block Receive functions don’t support variable length messages, is that correct? Any work arounds? We also need to connect to an IP gateway device that sends asynchronous messages can the s7-1200 support this? Sorry to ask such basic questions I did step 7 programming about 20 years ago so I’m totally out touch with modern PLCs. I want to recommend that we start to use the s7-1200 to replace our existing solution. Thanks in advance
ieTechSup Posts: 5 Rating: (0)
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8/17/2010 9:37 PM	Rate (1)
Galen Advanced Member Joined: 10/1/2008 Last visit: 1/27/2025 Posts: 21 Rating: (7)	The ability to receive variable length messages was added in firmware update V1.0.2. It is called "Ad hoc mode". http://support.automation.siemens.com/WW/view/en/38710558 PROFINET TCP "Ad hoc mode" "Ad hoc mode" for TCP is supported by the S7-1200. (The "Ad hoc mode" exists only with the TCP protocol variant.) Assign a value of "65535" to the LEN parameter to select "Ad hoc mode". With "Ad hoc mode", a maximum of 1472 bytes can be received. This affects the descriptions of the TRCV_C and TRCV instructions in Section 6.2.5 "Open Ethernet communication" of the 11/2009 version of the S7-1200 System Manual.

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This contribution was helpful to 1 thankful Users J_Bell

8/18/2010 12:25 PM	Rate (0)
ieTechSup Posts: 5 Rating: (0)	Galen many thanks for your help.
ieTechSup Posts: 5 Rating: (0)
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