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S7-1200 PUT pointer parameter

Created by: salrandazzo at: 7/9/2014 4:38 PM (18 Replies)

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7/9/2014 4:38 PM	Rate (0)
salrandazzo Posts: 57 Rating: (8)	When you use a PUT (or even GET) instruction on S7-1200 you've to define, between others, ADDRESS_1 and SD_1 parameters. They're defined as "remote" and "variant" parameters, and they've to be defined like "P#DB1.DBX0.0 BYTE 100". Everything works smoothly with constant parameters. But I didn't find any way to attach there a variable. There is no way to define a DB variable as "remote" or "variant", so no way to programmatically define source, destination and data transfer size. Any known way to solve the problem? I use SCL language, but I think that language should not be an issue. Thanks for helping.
salrandazzo Posts: 57 Rating: (8)
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7/9/2014 7:07 PM	Rate (0)
0_Einstein Grandmaster-Expert Joined: 7/7/2010 Last visit: 12/23/2025 Posts: 16325 Rating: (2520)	salrandazzo When you use a PUT (or even GET) instruction on S7-1200 you've to define, between others, ADDRESS_1 and SD_1 parameters. They're defined as "remote" and "variant" parameters, and they've to be defined like "P#DB1.DBX0.0 BYTE 100". Everything works smoothly with constant parameters. But I didn't find any way to attach there a variable. There is no way to define a DB variable as "remote" or "variant", so no way to programmatically define source, destination and data transfer size. Any known way to solve the problem? I use SCL language, but I think that language should not be an issue. Thanks for helping. Maybe if you posted some sample code we can help. The get/put is meant for an existing PLC in the project, or in a compatible s7 subnet in another project. What are you wanting to change, and more importantly, why?
	science guy
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7/10/2014 8:58 AM	Rate (0)
salrandazzo Posts: 57 Rating: (8)	huggy_d1 Maybe if you posted some sample code we can help. The get/put is meant for an existing PLC in the project, or in a compatible s7 subnet in another project. What are you wanting to change, and more importantly, why? You're right Huggy. So, the situation is that I've to transfer 800 bytes from a PLC to another one. Both are S7-1200. The PUT operation has a inner limit of 212 bytes, so I've to arrange four 200bytes PUT operations. I could establish a loop, using variables to parametrise the PUT operation. But I can't find a way to pass a "remote" variable to the ADDR_1 parameter. Same happens for the SD_1 parameter that needs a "variant" variable. This is the code with mutlple PUT operations handled by a CASE switch instruction: CASE #put_step OF 0: // no-op IF #put_req THEN #put_step := 1; #final_done := false; #error_mem := false; #status_mem := 0; END_IF; ; 1: // first slice operation "PUT_DB"(REQ := #put_req, ID := #connection_ID, DONE => #put_done, ERROR => #put_error, STATUS => #put_status, ADDR_1 := p#db16.dbx0.0 byte 200, SD_1 := p#db16.dbx0.0 byte 200); IF #put_done THEN #put_req := false; #put_step := 2; END_IF; 2: // first slice complete, trigger second slice "PUT_DB"(REQ :=#put_req, ID := #connection_ID, DONE => #put_done, ERROR => #put_error, STATUS => #put_status, ADDR_1 := p#db16.dbx200.0 byte 200, SD_1 := p#db16.dbx200.0 byte 200); #put_req := true; #put_step := 3; 3: // second slice operation "PUT_DB"(REQ := #put_req, ID := #connection_ID, DONE => #put_done, ERROR => #put_error, STATUS => #put_status, ADDR_1 := p#db16.dbx200.0 byte 200, SD_1 := p#db16.dbx200.0 byte 200); IF #put_done THEN #put_req := false; #put_step := 4; END_IF; 4: // second slice complete, trigger third slice "PUT_DB"(REQ :=#put_req, ID := #connection_ID, DONE => #put_done, ERROR => #put_error, STATUS => #put_status, ADDR_1 := p#db16.dbx400.0 byte 200, SD_1 := p#db16.dbx400.0 byte 200); #put_req := true; #put_step := 5; 5: // third slice operation "PUT_DB"(REQ := #put_req, ID := #connection_ID, DONE => #put_done, ERROR => #put_error, STATUS => #put_status, ADDR_1 := p#db16.dbx400.0 byte 200, SD_1 := p#db16.dbx400.0 byte 200); IF #put_done THEN #put_req := false; #put_step := 6; END_IF; 6: // third slice complete, trigger last slice "PUT_DB"(REQ :=#put_req, ID := #connection_ID, DONE => #put_done, ERROR => #put_error, STATUS => #put_status, ADDR_1 := p#db16.dbx600.0 byte 200, SD_1 := p#db16.dbx600.0 byte 200); #put_req := true; #put_step := 7; 7: // last slice operation "PUT_DB"(REQ := #put_req, ID := #connection_ID, DONE => #put_done, ERROR => #put_error, STATUS => #put_status, ADDR_1 := p#db16.dbx600.0 byte 200, SD_1 := p#db16.dbx600.0 byte 200); IF #put_done THEN #put_req := false; #final_done := true; #put_step := 0; END_IF; ELSE #put_step := 0; END_CASE; IF #put_error THEN #error_mem := true; #status_mem := #put_status; #put_step := 0; #put_req := false; END_IF; As you can see, I'm forced to use a complicated sequence of PUT calls in order to transfer four subsequent slices of 200bytes, using fixed pointers. With pointer variables it would be much easier to increment pointers using a four step loop. BTW, steps 2, 4 and 6 are used to trigger the PUT operation with a rising edge of the REQ signal. Hope it's easy to understand.
salrandazzo Posts: 57 Rating: (8)
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7/10/2014 12:15 PM	Rate (1)
0_Einstein Grandmaster-Expert Joined: 7/7/2010 Last visit: 12/23/2025 Posts: 16325 Rating: (2520)	With four connection id's transmit all four at once.
	science guy
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7/10/2014 12:37 PM	Rate (0)
salrandazzo Posts: 57 Rating: (8)	huggy_d1 With four connection id's transmit all four at once. Yes.... but..... what if other connections are already busy? My system is composed by 18 PLCs, and S7-1200 has a limit of 8 S7 connections..... I already have hard time setting up a sort of a round chain transmission to reach all of them. Anyway, yes, that's a good idea! I'll think how to use more than a connection to link two PLCs. Thank you Huggy. From your suggestion I get the sensation that the idea of a "remote" and/ or "variant" variable still remains just a mythe. S7-1200 and pointers are an unhappy love story......
salrandazzo Posts: 57 Rating: (8)
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7/10/2014 2:59 PM	Rate (0)
0_Einstein Grandmaster-Expert Joined: 7/7/2010 Last visit: 12/23/2025 Posts: 16325 Rating: (2520)	salrandazzo huggy_d1 With four connection id's transmit all four at once. Yes.... but..... what if other connections are already busy? My system is composed by 18 PLCs, and S7-1200 has a limit of 8 S7 connections..... I already have hard time setting up a sort of a round chain transmission to reach all of them. Anyway, yes, that's a good idea! I'll think how to use more than a connection to link two PLCs. Thank you Huggy. From your suggestion I get the sensation that the idea of a "remote" and/ or "variant" variable still remains just a mythe. S7-1200 and pointers are an unhappy love story...... If you are just using the s7-1200's for remote I/O, you can use the I-Device option and have everything just work without any puts/gets. Or, if most of the 800 bytes is I/O, you can use I-Device for the I/O, and just use the PUTs for what's left.
	science guy
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7/10/2014 3:17 PM	Rate (0)
salrandazzo Posts: 57 Rating: (8)	huggy_d1 If you are just using the s7-1200's for remote I/O, you can use the I-Device option and have everything just work without any puts/gets. Or, if most of the 800 bytes is I/O, you can use I-Device for the I/O, and just use the PUTs for what's left. Thanks for hing. Unfortunately they are configuration data, remote I/O is handled by each PLC in an autonomous way. Even if the network fails, after configuration each PLC will be able to survive and operate by itself. I just asked about "remote" and "variant" parameter to be sure that there is no way to use them as a variable. It's a pity that 1200 family doesn't allow for pointer arithmetics...
salrandazzo Posts: 57 Rating: (8)
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7/10/2014 3:28 PM	Rate (0)
0_Einstein Grandmaster-Expert Joined: 7/7/2010 Last visit: 12/23/2025 Posts: 16325 Rating: (2520)	salrandazzo Thanks for hing. Unfortunately they are configuration data, remote I/O is handled by each PLC in an autonomous way. Even if the network fails, after configuration each PLC will be able to survive and operate by itself. I just asked about "remote" and "variant" parameter to be sure that there is no way to use them as a variable. It's a pity that 1200 family doesn't allow for pointer arithmetics... If you use fieldread you can 1) select a variable DB #, 2) select where to start reading, and 3) select how many bytes to read. Using that, you could populate a single DBn.ArrayOfBytes, send the ArrayOfBytes, update the 1/2/3, and send again using the same ArrayOfBytes. The FieldRead/FieldWrite on the s7-1200 is the pointer substitute. With some imagination and FBs, you can craft a pretty good simulation of the way legacy s7-300/400 allow what you are after.
	science guy
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6/17/2015 10:12 PM	Rate (0)
banconi Silver Member Joined: 3/19/2010 Last visit: 6/15/2025 Posts: 439 Rating: (12)	Please, how does the syntax go when using those pointers? One simple example, I beg you, just with two different destinations. Thanx in advance

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8/20/2015 11:56 AM	Rate (0)
MrLam Posts: 1 Rating: (0)	I have same issue like salrandazzo. How i can use that address as a variable ? I am really appreciated with all helps ??
MrLam Posts: 1 Rating: (0)
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