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modifying operand value

Created by: DERVIN_1405 at: 3/18/2021 6:57 AM (7 Replies)

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3/18/2021 6:57 AM	Rate (0)
DERVIN_1405 Posts: 2 Rating: (0)	Hi ! I am new in PLC programming. I try to create a simple on/off instruction to familiarize myself in using siemens TIA portal & plcsim. But when I try to modify the operand, the state of the rung doesn't change even the message on the info tab is that the "operand is successfully modified". Can anyone help me how to solve this problem. Thank you in advance! Attachment plcsim problem.png (225 Downloads)
DERVIN_1405 Posts: 2 Rating: (0)
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3/18/2021 7:12 AM	Rate (0)
Mr.V Silver Member Joined: 6/19/2019 Last visit: 10/29/2024 Posts: 705 Rating: (76)	Hello, Go to Watch and force table and there put your input I0.0 and I0.1 and there you can force on your input and you will see then changing status

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7/22/2024 3:17 AM	Rate (0)
Farzad.Soud Joined: 11/30/2023 Last visit: 7/23/2024 Posts: 2 Rating: (0)	Hello, I am also new to TIA portal programming. I have an exact problem. But the output used to be activated just by modifying the input operand. Why do I suddenly have to force the input to activate the output? Farzad

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7/22/2024 3:59 AM	Rate (0)
@rturas Experienced Member Joined: 1/27/2009 Last visit: 10/22/2024 Posts: 172 Rating: (8)	Farzad.Soud Hello, I am also new to TIA portal programming. I have an exact problem. But the output used to be activated just by modifying the input operand. Why do I suddenly have to force the input to activate the output? Farzad Hello Farzad.Soud, The short answer would be - because that's the way it is. Please investigate this Siemens manual entry Entry ID: 91696622? and read about force table and watch table. You will find out the differences and how to use them in proper way. In addition, if your input is connected directly to the output and you do not want to mess with force table, then you could simply add some memory bit in parallel and operate it.
	Last edited by: @rturas at: 07/22/2024 04:00:38 typos The only thing necessary for the triumph of evil is for good men to do nothing
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7/22/2024 5:30 AM	Rate (0)
qwazee Platinum Expert Joined: 3/30/2020 Last visit: 11/5/2024 Posts: 4926 Rating: (1007)	Farzad.Soud Hello, I am also new to TIA portal programming. I have an exact problem. But the output used to be activated just by modifying the input operand. Why do I suddenly have to force the input to activate the output? Farzad Setting a tag (variable) to a value is only possible if the tag is not being written to already. What we use as inputs is in actual fact a block of memory. That block of memory is written to on the start of each PLC cycle. The actual / physical input values are written to that block of memory. Using the force function makes the PLC "disconnect" from the physical input peripheral and use the force value instead. The process of writing peripheral inputs values into the input memory happens even when doing a simulation. The inputs of a simulation can be manipulated from the PLCSIM simulator through provided tables. It is possible to have the input memory not be updated by the peripherals. But that will not be detailed now. Inputs and outputs can be forced by force tables. Other memory locations cannot. As stated before: a tag that is written overwrites the attempt from the user (Step7) to manipulate its value.
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7/23/2024 6:26 AM	Rate (0)
Farzad.Soud Joined: 11/30/2023 Last visit: 7/23/2024 Posts: 2 Rating: (0)	Thank you to everyone for trying to help me. I learned a lot from your answers. However, I could learn how to activate an output without forcing it through a simulator. Here are the steps I took to activate the output without forcing it. 1. I used to add my in and output tags to the CPU 1212 DC/DC/DC "IO"s. 2. I deleted the tags and added separate DI and DQ modules to the hardware configuration. Please see the attached image. The image "1".png" shows the tags in the CPU 1212 DC/DC/DC "IO"s are deleted. The image "2" shows the tags entered in the new DI modules. I entered tags to DQ modules as well. 3. I added my tags to the new DI and DQ modules IOs. 4. I created a simple program and saved, compiled, and loaded it into the PLC. (Please note that I was already running the simulation.) 5. When I activate the input, the output activates immediately without forcing it. The problem with forcing was that I couldn't quickly activate each instruction I wanted to practice. For example, to activate and deactivate signals to the "Counters" instruction, I had to go to the force table to force the signal. I would appreciate it if you could tell me why adding new DI and DQ helps to activate the output immediately. Again, Thank you for your information. Attachment Screenshot 2024-07-22 232658.png (146 Downloads)
	Last edited by: Farzad.Soud at: 07/23/2024 06:28:16 Last edited by: Farzad.Soud at: 07/23/2024 06:36:31
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7/23/2024 8:49 AM	Rate (0)
qwazee Platinum Expert Joined: 3/30/2020 Last visit: 11/5/2024 Posts: 4926 Rating: (1007)	Note the icons on the picture of the PLC that is shown in the screen capture. These icons show that the FORCE mode is active and that the hardware configuration has not been loaded properly. The hardware configuration cannot be loaded while there is an online view active. Go to offline first. Then select the PLC in the project tree. Execute a download (PC -> PLC). Consider using memory bits if you are not intending to use the hardware inputs to supply input states. The software will track which tags goes to which address. So you can have the tags temporarily connect memory bit addresses (%Mx.y). Later you can rename to the actual input addresses.\ The other option would be to set the update of the inputs to "none" as shown in the picture.
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7/23/2024 2:18 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 11/5/2024 Posts: 15385 Rating: (2443)	Have you considered watch tables or configuring the PLC Simulator's input table that allows you to pre-configure digital and analog input values with an associated time since startup type of thing. You can simulate quite a bit. And, with PLC Sim Advanced and S7-1500, you can access the simulator's API from your own code in Visual Studio (if I have read the documentation correctly).
	science guy
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