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Created by: Higgor Olipe at: 10/26/2016 9:58 PM (9 Replies)

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10/26/2016 9:58 PM	Rate (0)
Higgor Olipe Posts: 51 Rating: (0)	Hi everybody, I've read about read back here on the support and I notice that I need some theory about it. On my client I have a project running, and I'm afraid to loose some data on it. For example when the cause is a fase-loss or someone turn off the PLC (I know it is difficult to happend but thinking in worst case) I need to maintain datas on blocks that I made. Take a look to the pic attachment. I have 100 box on my system and need to save all the individual values when some thing wrong happend. Can someone explain more about it and guide me to the solution? Thank you so much. Attachment PIC.png (522 Downloads)
Higgor Olipe Posts: 51 Rating: (0)
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10/27/2016 8:01 AM	Rate (2)
Oreca Platinum Expert Joined: 3/14/2008 Last visit: 11/14/2024 Posts: 2130 Rating: (953)	Hi Higgor. A readback means that you are taking the online values of the PLC and upload it in your CFC program. This can be done with three options: All parameters, OCM or designated parameters. All parameters means what it says.. In this case FC inputs interconnected to the chart IOs are read back. OCM means: "Operator Control and Monitoring". These are the parameters an operator can influence, such as PID Gain settings, monitoring time of a valve etc. When a parameter is classified as a OCM, it means that parameter has the: "S7_m_c:='true'" attribute. Designated parameters means: All parameters that have the attribute: "S7_read_back:='true'". The default setting for PCS7 is: "OCM". There are some rules: - Only in/out and in parameters can be read back. - A readback is possible only when the online/offline program is equal - An ARRAY, ANY, POINTER or UDT type is not included - Unconfigured inputs are not read back ("S7_param:='false'") - Inputs connected to an SFC - If a block type has the attribute: "S7_read_back:='false'". So, it looks you have a custom block made. If the parameters you want to read back have all the attribute: "S7_m_c:='true'", then you can read them back by selecting the OCM option.
	If I could help you, you can use the RATE button. Thank you. Prospact Netherlands...your PCS7 and PCS neo Expert Topic: PCS7 Complete Overview
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10/27/2016 1:16 PM	Rate (0)
Higgor Olipe Posts: 51 Rating: (0)	Hi Oreca, Thanks for your explanation. It was very helpfull. Lets go ahead: I have a custom block; I have all attributes "S7_m_c:='true" and check "Readback enable" on properties's block. My question: Imagine some time of day, factory close and occurs phase loss. No one is there to do some thing. PLC shutdown. I understand the known about readback. But in this situation, what can I do to avoid loose information in my program? My question is: whose responsability to save data: me or PLC? Do you know what I mean? Thanks a lot. Best regards
Higgor Olipe Posts: 51 Rating: (0)
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10/28/2016 4:21 AM	Rate (0)
Oreca Platinum Expert Joined: 3/14/2008 Last visit: 11/14/2024 Posts: 2130 Rating: (953)	Hi Higgor, Well, the only thing you could do is to do a readback more often. The operator can have some procedures to make print screens for example once a day, week of the important parameters. When a PLC is dead, yeah you will loose everything and hope you have some recent backup data. Another option is to make use of user archives. User archives is mainly used for recipe parameters. The option is a pain in the ass to use, but it will save your paramters on the server(s). You can write and read to the PLC by commands or by creating a self made block and you can make a script to make a copy every day, week or so and store that on a backup PC. In case something is wrong, you can load the backup back to the OS server. The UA is synchronized with the other server in case of redundant operation. And another option is to generate a print job (report) of all the important data. You can schedule this as you like. You will have some typing work after a PLC replacement, but luckily this is rare.
	If I could help you, you can use the RATE button. Thank you. Prospact Netherlands...your PCS7 and PCS neo Expert Topic: PCS7 Complete Overview
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10/31/2016 2:48 PM	Rate (0)
Higgor Olipe Posts: 51 Rating: (0)	Oreca thank you for the tips. I'll read more about every thing that you said. I need to know more about subject. Do you have any document about it (the best option in you opinion)? Thank you again. Best regards.
Higgor Olipe Posts: 51 Rating: (0)	Last edited by: Higgor Olipe at: 10/31/2016 2:49:09 PM
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9/12/2017 9:41 AM	Rate (0)
PCS7_programmer Regular Member Joined: 8/13/2014 Last visit: 10/7/2024 Posts: 3 Rating: (0)	Oreca - An ARRAY, ANY, POINTER or UDT type is not included Custom defined STRUCT(containing STRINGs) or STRINGs it self IOs aren't include too, are they?
	Last edited by: PCS7_programmer at: 9/12/2017 10:59:45 AM
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9/12/2017 12:05 PM	Rate (0)
Oreca Platinum Expert Joined: 3/14/2008 Last visit: 11/14/2024 Posts: 2130 Rating: (953)	Hi, STRUCT type is allowed and the readback is done for the whole struct, you don't need to specify which parameter in the struct must be readback unlike OCM parameters -> S7_xm_c for parameters inside a struct and S7_m_c for parameters without a struct.
	If I could help you, you can use the RATE button. Thank you. Prospact Netherlands...your PCS7 and PCS neo Expert Topic: PCS7 Complete Overview
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9/13/2017 4:10 AM	Rate (0)
PCS7_programmer Regular Member Joined: 8/13/2014 Last visit: 10/7/2024 Posts: 3 Rating: (0)	Oreca STRUCT type is allowed and the readback is done for the whole struct, you don't need to specify which parameter in the struct must be readback unlike OCM parameters -> S7_xm_c for parameters inside a struct and S7_m_c for parameters without a struct. Good day Sir, that's strange, I''ve the Output struct(w mix type fields) bound with other block In and when it read-backed, it get nothing. Does bounds declines read-back for output?

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9/13/2017 7:20 AM	Rate (0)
Oreca Platinum Expert Joined: 3/14/2008 Last visit: 11/14/2024 Posts: 2130 Rating: (953)	Hi, Outputs cannot be read back.. If an output is connected to an input, that input cannot be read back either. If you have an input which is a struct and nothing is connected, than it should be possible to readback the online values.
	If I could help you, you can use the RATE button. Thank you. Prospact Netherlands...your PCS7 and PCS neo Expert Topic: PCS7 Complete Overview
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9/14/2017 9:26 AM	Rate (0)
PCS7_programmer Regular Member Joined: 8/13/2014 Last visit: 10/7/2024 Posts: 3 Rating: (0)	Oreca Outputs cannot be read back.. Hi, In CFC for Simatic S7 help, "Properties - Block\Chart" part for "General" tab, it says: "Depending on the scope set in the Read Back dialog box, all block I/Os are read back". I've thought I\O means Input\Output.

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