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Industry Library V8.0 Block Issues

Created by: JoseAngel at: 11/12/2014 2:43 PM (7 Replies)

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11/12/2014 2:43 PM	Rate (0)
JoseAngel Posts: 5 Rating: (0)	Friends and colleagues: I've been working with the functions library meant to be used in PCS7 called "Indutry Library" v8.0. I am doing a study to determine how all these functions work in Step 7 using CFC. In last months i have been testing all the blocks but i have problems understanding/parameterizing some blocks in order to conclude they work perfectly. I don't understand how to use the block S7SplitRange contained in the IL. As we can see in the manual (diagram called "connection in CFC") is supposed to be used with S7MV3P to control the setpoint of that block. That is not very clear to me, as the real use of the PID controller placed behind the S7SplitRange. If anyone has seen the manual and understand what all that means and could explain i've would be very thankful. Attachment S7IL80b.pdf (155 Downloads)
JoseAngel Posts: 5 Rating: (0)
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11/12/2014 3:39 PM	Rate (1)
hdhosseini Diamond Member Joined: 1/28/2009 Last visit: 10/26/2024 Posts: 6852 Rating: (1365)	JoseAngel Friends and colleagues: I've been working with the functions library meant to be used in PCS7 called "Indutry Library" v8.0. I am doing a study to determine how all these functions work in Step 7 using CFC. In last months i have been testing all the blocks but i have problems understanding/parameterizing some blocks in order to conclude they work perfectly. I don't understand how to use the block S7SplitRange contained in the IL. As we can see in the manual (diagram called "connection in CFC") is supposed to be used with S7MV3P to control the setpoint of that block. That is not very clear to me, as the real use of the PID controller placed behind the S7SplitRange. If anyone has seen the manual and understand what all that means and could explain i've would be very thankful. Hello JoseAngel, As general structure of a split-range control suggests, you need a PID controller to reach to a defined set-point via several actuators with a determining portion of each actuator with a simple line function.The portion of each actuator is determined from process requirement and PID controller is crucial because it performs the main control task. For other control structure, read more here: Controlling with SIMATIC I hope these comments help, Hamid Hosseini
	Last edited by: hdhosseini at: 11/12/2014 5:37 PM // link modified Demo Channel on Youtube
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11/12/2014 4:46 PM	Rate (0)
JoseAngel Posts: 5 Rating: (0)	Alright, i have used before the PID block to achieve a set point only manipulating one variable. Now if i want to reach a set point,modifying several variables it is recomended that i use SplitRange block. That is what i understand now, tell me if i am right. Other thing, looks like i must use the block with the actuator being controlled by S7MV3P block, is that correct? I say so for the conection between QSPLIT and STATUS_1. Thank you so much.
JoseAngel Posts: 5 Rating: (0)
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11/12/2014 5:45 PM	Rate (0)
hdhosseini Diamond Member Joined: 1/28/2009 Last visit: 10/26/2024 Posts: 6852 Rating: (1365)	JoseAngel ... . Now if i want to reach a set point,modifying several variables it is recomended that i use SplitRange block. That is what i understand now, tell me if i am right. Other thing, looks like i must use the block with the actuator being controlled by S7MV3P block, is that correct? I say so for the conection between QSPLIT and STATUS_1. Thank you so much. In brief, split range is suitable for processes that several causes are in-coperated to built up the process value such as pressure , temperature or others.Same set-point and same PID but with different effects of main PID output on different actuators. My suggestion would be adhereing to suggest layout by the manual. Block "S7MV3P " is important to operate the actuators based on their portion, action the valve based on re-start behavior and also providing the feedbacks to the SplitRange block (conection between QSPLIT and STATUS_1).These connections perhap are important for proper operation of the whole system.
	Last edited by: hdhosseini at: 11/12/2014 5:46 PM Demo Channel on Youtube
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11/12/2014 6:53 PM	Rate (0)
JoseAngel Posts: 5 Rating: (0)	Ok, later in these days i'll do the tests. I'll write soon again with the results. Thanks a lot.
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11/13/2014 7:43 PM	Rate (0)
JoseAngel Posts: 5 Rating: (0)	Hi again, thanks to your help i was able to check how does the SplitRange block work. It works just great, maybe the only thing is that PID block takes some time achieving the set point, but considering that i was controlling four different actuators that is not a problem at all. Maybe there were better values for GAIN and TI (still i don't use derivative action), and i was not using self tunning (still i don't know how). 1. Now i am using the S7MVLd block, it says in the manual it is used for "Retrieving the Manipulated Variable for the Controller". I think it must be used in case the PLC enters in STOP mode and when i want to start up the control again i won't need the PID block to begin again from zero, by calling it somehow. It will save de old value of the manipulated variable and resume with that state. I was simulating in PLCSIM and when the controller entered in stop mode and then resumed the operation the PID block somehow was still using the LMN value he had before the STOP, without using S7MVLd, the block seems useless then, i don't know what i am doing wrong. Maybe in real operation that would not happen. 2. With Block S7Aggr08 ... Well, i was reading the manual but i did not understand anything at all. Maybe my lack of experience in the field. If you can help me again, or anyone who reads this, with these two issues i would be very thankful (again).
JoseAngel Posts: 5 Rating: (0)	Last edited by: JoseAngel at: 11/13/2014 7:44 PM
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11/14/2014 10:03 PM	Rate (0)
hdhosseini Diamond Member Joined: 1/28/2009 Last visit: 10/26/2024 Posts: 6852 Rating: (1365)	JoseAngel ... 1. Now i am using the S7MVLd block, it says in the manual it is used for "Retrieving the Manipulated Variable for the Controller". I think it must be used in case the PLC enters in STOP mode and when i want to start up the control again i won't need the PID block to begin again from zero, by calling it somehow. It will save de old value of the manipulated variable and resume with that state. I was simulating in PLCSIM and when the controller entered in stop mode and then resumed the operation the PID block somehow was still using the LMN value he had before the STOP, without using S7MVLd, the block seems useless then, i don't know what i am doing wrong. Maybe in real operation that would not happen. 2. With Block S7Aggr08 ... Well, i was reading the manual but i did not understand anything at all. Maybe my lack of experience in the field. ... Hello JoseAngel, Some fast notes regarding your questions: Case related to "S7MVLd": Defining the re-start behavior of PID controller depends on requirements of your process.Perhaps the best reaction to CPU stop and reaction to mode transition in CPU would be putting the controller in manual mode and keep the LMN on a safe value.Normally, safety regarding a loop is implemented in hardware in field such as pneumatic strategies.I think, you need to test this behavior in a test set-up.When a CPU enters STOP mode, normally a shut-down happens and there is possibility of process change (increase or decrease).In this case , keep the last valid LMN on start-up and then putting system in auto may cause a jump in LMN and this is not a desired respnse.There are other safe reactions in case of power outage/CPU in STOP for PID controllers that discussed in Controlling with SIMATIC. For the case related to "S7Aggr08" , you need to test it.Just provid the minimum information, in case of having several units such as pumps and plan to start them based on minimum run-time(in equal situations).To simplify your case, use it in "Operating Hours-Dependent Switching On/Off " mode that is explained in page#60. I hope these explanations helps, Hamid Hoseeini
	Last edited by: hdhosseini at: 11/14/2014 10:06 PM Demo Channel on Youtube
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11/26/2014 4:49 PM	Rate (0)
JoseAngel Posts: 5 Rating: (0)	Hello Hamid, i will try later these blocks having in mind your opinions. Thanks so much
JoseAngel Posts: 5 Rating: (0)
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