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Map HTML responses to S7 1200 variables

Created by: HamaYoko at: 12/24/2011 1:56 PM (12 Replies)

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12/24/2011 1:56 PM	Rate (0)
HamaYoko Posts: 19 Rating: (0)	Can anyone write a program for the S7-1200 that reads HTML responses? I need a S7 1200 program to readvariables fromvarious web servers. (Apache or IIS) From a simple web browser (IE, Firefox..etc) variables can be accessed in the simplest way like: http://servername/variable_name.html So the html response can be a simple "1" or "0" for boolean variables. (f.e.) Ineed to read this variables from S7, and I need to incorporate them in the user program. in a DB for example like input parameters. Maybe TCON, TSEND?? Where can I find an example connecting S7 to a Mail Server, Telnet or Web server? I think without Oc Wizard it's going to be a little bit hard... Any other ideas? For giving you a background of the problem,we have various webServers to control their powerlines. For example,if one of them has a failure, the S7switches itoff.10 seconds later S7will restart the computer again. If one of the server is not needed, S7 switches off it also! Let's save the planet! Can you help me? Thanks in advance. Yoko
HamaYoko Posts: 19 Rating: (0)	Last edited by: HamaYoko at: 12/24/2011 5:42 PM Last edited by: HamaYoko at: 12/24/2011 3:40 PM
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12/27/2011 2:02 PM	Rate (0)
0_Einstein Diamond Member Joined: 7/7/2010 Last visit: 11/15/2024 Posts: 15402 Rating: (2446)	Maybe it is possible for these web servers to perform tasks to get the variable data from the S7-1200 PLC(s) as needed per your schedule using the built-in web server on the S7-1200 PLCs with firmware 2.x and TIA Portal V11 It would seem simple enough to have a small powershell or windows shell or vb script run to get custom web page data from the PLC and read tags from DBs, etc. The results can then be acted upon or added to a text file or local web server database. Maybe this approach is useful.
	science guy
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12/27/2011 5:35 PM	Rate (0)
HamaYoko Posts: 19 Rating: (0)	Hello and thank you very much for your answer. Theworkflow you are describingwas my second choice, because I needed to log on the S7 1200 if I wanted to WRITE values on it. I'm using TSEND_C and TRECV_C for reading from the web server and then in the S7 I'm writing a segment to process the information. With this method I don't need to use the admin user in the S7 nor the builtin webserver. I can read and write to a self created netcat based server using Open User Communication, but I'm actually fighting with a WebServer because I'm just writing the correct querys. Maybe I will write a FB for reading from standard webservers based on input URLs or something similar. Anyone has another idea? Thank you very much, Yoko
HamaYoko Posts: 19 Rating: (0)
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12/27/2011 5:48 PM	Rate (0)
0_Einstein Diamond Member Joined: 7/7/2010 Last visit: 11/15/2024 Posts: 15402 Rating: (2446)	To me, the best solution sounds more like one that has no plc. If a system is not required, have the PC issue a shutdown. When it is required, send a Wake-On-Lan magic packet to get the computer back online. For failure or lock-up, a hardware watchdog is simple hardware, or can be highly complex if that is what is required. I guess I am not a fan of turning off power to a running server just because of a hung process or it simply is not needed at the moment. I would prefer to send a shutdown command via the network (shutdown.exe), and if it fails to shut down, fix the problem causing it to break. I do understand there is inherent value in the tools you wish to build for other reasons though. I believe someone else here has had some success with SQL server connections and commands.
	science guy
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12/27/2011 5:59 PM	Rate (0)
HamaYoko Posts: 19 Rating: (0)	Hello, Of course I was going to use both magic packet and shutdown command. But at least I need to cut the power supply so the PLC is very important in this case. For getting a response via TSEND command to the server I need to send this: "GET /cgi-bin/example.html HTTP/1.0" followed by 2 carriage returns. It corresponds to http://serveraddress/cgi-bin/example.html FIRST QUESTION: -------------------------------- How can I store"GET /.. with the 2 carriage ret.)in a string in a DBusing TIA portal V11? I don't know how to store the 2 carriage returns chr(13) SECOND QUESTION ------------------------------------ In the response of the Web server using Internet Explorer, I get the response: "0" (char 30) or "1", but using telnet for testing it I need to filter the answer because the answer of the serveris like: HTTP/1.0 200OK Content-type: text/html 0 Connection lost Any ideas? So... we are maping HTTP responses in PLC variables!! Thank you very much.
HamaYoko Posts: 19 Rating: (0)
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12/27/2011 6:13 PM	Rate (0)
0_Einstein Diamond Member Joined: 7/7/2010 Last visit: 11/15/2024 Posts: 15402 Rating: (2446)	HamaYoko ... "GET /cgi-bin/example.html HTTP/1.0" followed by 2 carriage returns. It corresponds to http://serveraddress/cgi-bin/example.html FIRST QUESTION: -------------------------------- How can I store"GET /.. with the 2 carriage ret.)in a string in a DBusing TIA portal V11? I don't know how to store the 2 carriage returns chr(13) SECOND QUESTION ------------------------------------ In the response of the Web server using Internet Explorer, I get the response: "0" (char 30) or "1", but using telnet for testing it I need to filter the answer because the answer of the serveris like: HTTP/1.0 200OK Content-type: text/html 0 Connection lost Any ideas? So... we are maping HTTP responses in PLC variables!! Thank you very much. Create a DB for your Tsend/Trcv buffers. Tsend_buff, Trcv_buff perhaps Create a DB to populate the buffer for Tsend (it's where your outbound command goes). "GET /cgi-bin/" + webpage + " HTTP/1.0" <DB_send> cr = char = 16#0D $cr = string[1] = "x" // this is the tricky part and you need to do this once in a first-scan routine to copy the character value into the location pointed at by the 'x' character using absolute addressing. command = string[3] = "GET " path = string[20] = "/cgi-bin/" webpage = string[20] = "example.html" protocol = string[10] = " HTTP/" version = string[5] = "1.0" //+ $cr + $cr <- do this in first-scan by appending the $cr after making it. send_command = string = "" Now your send string is built as needed to by appending the right pieces together at runtime. You can use the watch table to see it work live. This is likely to get you close in building your command string. Then stuff it into the buffer for sending. For the response, receive it into a string, then parse it to pick out the result you need. Look for OK, and if it does not say what you expect, you will want to send again, say up to 3 attempts to get a proper response. After 3 failures, you _may be able to assume it is not working properly.
	science guy
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12/27/2011 6:34 PM	Rate (0)
HamaYoko Posts: 19 Rating: (0)	Hello, very good ideas! But unfortunately it seems to be in SCL! I have TIA Portal V11 SP2 but the CPU is V2.02 so it does not support SCL I supposed that with FUP or KOP was going to bevery tricky! Do you think that it can be done without SCL? Thank you very much, Yoko
HamaYoko Posts: 19 Rating: (0)
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12/27/2011 6:54 PM	Rate (0)
0_Einstein Diamond Member Joined: 7/7/2010 Last visit: 11/15/2024 Posts: 15402 Rating: (2446)	HamaYoko Hello, very good ideas! But unfortunately it seems to be in SCL! I have TIA Portal V11 SP2 but the CPU is V2.02 so it does not support SCL I supposed that with FUP or KOP was going to bevery tricky! Do you think that it can be done without SCL? Thank you very much, Yoko I know it can be done without SCL.
	science guy
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12/27/2011 7:36 PM	Rate (0)
HamaYoko Posts: 19 Rating: (0)	OK, I'm gonna test it. See you soon. Thank you very much!
HamaYoko Posts: 19 Rating: (0)
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12/27/2011 8:46 PM	Rate (0)
0_Einstein Diamond Member Joined: 7/7/2010 Last visit: 11/15/2024 Posts: 15402 Rating: (2446)	Maybe it looks something like the attached images. Attachment String_Building.zip (520 Downloads)
	science guy
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