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Problem in creating a FC

Created by: dilip_123 at: 5/10/2011 8:32 PM (12 Replies)

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5/10/2011 8:32 PM	Rate (0)
dilip_123 Posts: 73 Rating: (0)	hii Iam having a problem while creating a FC. I am using a temporary variable for making a program. When I am calling this program in OB 1 for 1 time it is working. But more than 1 calling it is not working. My program is: Input---- IN1 bool IN2 bool RESET bool Output--- HORN Temp-- Temp1 bool Temp2 bool Temp3 bool A #IN1 A FP#Temp1 O A #IN2 A FP # Temp2 S #HORN A #RESET A FP #Temp3 R #HORN This program is not working when it is calling more than 1 time
dilip_123 Posts: 73 Rating: (0)
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5/10/2011 11:21 PM	Rate (0)
Hulzhex Gold Member Joined: 8/25/2005 Last visit: 7/5/2024 Posts: 1161 Rating: (110)	Hello dilip_123, you are using temporary variables. This are only within on call valid. After the end of your FC, this memory space may be used for another temporary variable. If you are using temporary variable you always have to initialize them befor reading. Good luck Sabine

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5/11/2011 5:23 AM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 9/10/2024 Posts: 6849 Rating: (1365)	dilip_123 Iam having a problem while creating a FC. I am using a temporary variable for making a program. When I am calling this program in OB 1 for 1 time it is working. But more than 1 calling it is not working. My program is: Input---- IN1 bool IN2 bool RESET bool Output--- HORN Temp-- Temp1 bool Temp2 bool Temp3 bool A #IN1 A FP#Temp1 O A #IN2 A FP # Temp2 S #HORN A #RESET A FP #Temp3 R #HORN This program is not working when it is calling more than 1st time In the code you implemented ,you need previous status of # Temp1,# Temp2,# Temp3 to run the program.Funcions are memory less and decide on current status of of parameters and temp variables can not retain data.You have option of using Function blocks for retaining the status of all parameters in DBs. regards
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5/12/2011 8:13 PM	Rate (0)
dilip_123 Posts: 73 Rating: (0)	hello sir Thanks for replying me. But it would be better if you make same programme using temporary variable so that i can understand Thanks
dilip_123 Posts: 73 Rating: (0)
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5/12/2011 8:40 PM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 9/10/2024 Posts: 6849 Rating: (1365)	dilip_123 But it would be better if you make same programme using temporary variable so that i can understand simply create a Function block and fill the declration table like before.write the codes and call FB each time with a data block. check the result. regards
	Demo Channel on Youtube
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5/13/2011 9:16 AM	Rate (0)
Wizard Diamond Member Joined: 4/24/2006 Last visit: 10/3/2024 Posts: 8744 Rating: (1168)	hdhosseini dilip_123 But it would be better if you make same programme using temporary variable so that i can understand simply create a Function block and fill the declration table like before.write the codes and call FB each time with a data block. check the result. regards Hello, In addition to hdhosseini's answer: You have to change your Temporary variables toStat variables. In that case the value will be saved in DB. Best regards, Wizard

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5/24/2011 10:41 AM	Rate (0)
Jazz_M Gold Member Joined: 9/6/2008 Last visit: 5/7/2022 Posts: 1121 Rating: (86)	Hi guys Well i am little curious to know, i have tested the same program that dilip_123 has done in FC and using temp variable. I have called it three times and using PLC sim i have simulated the same. I find it is working. for me.. Find the attached screen shot Attachment 1.JPG (129 Downloads)
	Last edited by: Tagolover at: 5/24/2011 10:46 AM Jazz
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5/24/2011 11:57 AM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 10/4/2024 Posts: 3024 Rating: (1054)	Tagolover I have called it three times and using PLC sim i have simulated the same. I find it is working. for me. You simply got lucky dear Tagolover. TEMP variables (aka local block data) MUST be initialised (written to first before being read from) to ensure error free operation under all conditions. You can find out more why the logicmay work ok under certain conditions in THIS thread.
	Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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5/24/2011 1:32 PM	Rate (0)
IBN-Service Posts: 8946 Rating: (999)	Fritz is 100% correct. In PLCSIM, perhaps you may be lucky. But in a real PLC, you surely may become crazy. You never know what happens in an time interrupt or whatever. Initialisation of TEMP local variables MUST BE DONE! If not, it will kick you in the a** one day, believe me, friend!
IBN-Service Posts: 8946 Rating: (999)
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5/24/2011 1:42 PM	Rate (0)
Jazz_M Gold Member Joined: 9/6/2008 Last visit: 5/7/2022 Posts: 1121 Rating: (86)	HI Fritz Well thank you, I think it be then better to use IN, OUT, INOUT, STAT, call only..... Have fun..
	Jazz
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