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Uncontrolled set/reset of 'INOUT' bits from FB

Created by: NSMCH at: 1/7/2015 8:32 PM (9 Replies)

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1/7/2015 8:32 PM	Rate (0)
NSMCH Member Joined: 2/25/2013 Last visit: 4/20/2022 Posts: 7 Rating: (0)	Hello all I am having a very strange problem that has kept me busy for days now. I created a FB (SCL) in Tia portal V13 that I use to control a Lenze drive. The main functions of this FB are positioning, manually control and calibrating a servo motor. To control the motor, I created a UDT that consists of bits, INTs and REALs. I declared this UDT in the FB's interface as 'INOUT'. The bits in this UDT are controlled from a HMI screen (proface in this case). The problem that I have is that the bits in this UDT start to reset/set when I set them once from the HMI... At first I thought there might be an overlapping adress, or a bug in my code that keeps setting/resetting the bit. I searched, and searched but I am now 100% sure, the bits are not set/reset by an error in the code... For example, a bit from this UDT is reset at 2 places in the FB. When I delete these 2 lines in the FB, the bit is still resetted sometimes. Then I thought that the HMI is resetting/setting this bit so I replaced the adresses with M adresses. I control the bits from watch tables, and still the set/reset problem! The partly solution I found to replace all the INOUTS from the UDT that I use as INPUT, declare them as INPUT. This works fine, but there are still 3 bits that need to reset in the FB and they behave unpredictable! I really don't know what to do anymore. I refuse to believe that this is a 'bug' in the tia portal software, as this is one of the basi pronciples of a PLC. There must be a fault in my code, but I really cannot find it. I don't use any form of indirect adressing in the FB. I work alot with Siemens V5.5, but tia portal is prety new to me but I think I understand it good enough to clear out a bug that would exist in my code. Does anyone have experience with unpredictable behaviour of INOUT variables in FBs? I can post the code from the FB if anyone would like that. Thank you for your opinion/help!

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1/8/2015 10:02 AM	Rate (0)
NSMCH Member Joined: 2/25/2013 Last visit: 4/20/2022 Posts: 7 Rating: (0)	Another strange remark: When I replace the INOUT-declared bit with a direct adress (Mx.x) it works fine... So when I use a marker adress, the bit does not behave unpredictable anymore!

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1/8/2015 10:24 AM	Rate (0)
NSMCH Member Joined: 2/25/2013 Last visit: 4/20/2022 Posts: 7 Rating: (0)	When I connect the marker adress to the FB connection of the INOUT bit (so I don't use the marker inside the FB, like in previous post) the problem still exists! So when I use a marker adress inside the FB, it works fine. But when I connect the marker adress outside of the FB to the INOUT variable, the bit sets/resets unpredictable...

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1/8/2015 10:34 AM	Rate (0)
TomDeWou Platinum Expert Joined: 11/15/2006 Last visit: 5/7/2021 Posts: 1319 Rating: (168)	How about the usage of the INOUT? Is there probably a not initialized value written to it? Do you use any uninitialized temp variables in your FB?
	Have Fun! TomDeWou
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1/8/2015 10:48 AM	Rate (0)
NSMCH Member Joined: 2/25/2013 Last visit: 4/20/2022 Posts: 7 Rating: (0)	I do not use any TEMP variable memory in this FB. I only write 2 times to the bit: 2 times "false". I'm sorry I've never heard of it... How do I initialize a variable?

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1/8/2015 11:06 AM	Rate (0)
NSMCH Member Joined: 2/25/2013 Last visit: 4/20/2022 Posts: 7 Rating: (0)	I call the FB (FB1) in another FB (FB2). The instance from FB1 is capsulated in the instance memory of FB2. I tried to use a single DB for the instance of FB1, but this has no effect...

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1/8/2015 11:54 AM	Rate (0)
NSMCH Member Joined: 2/25/2013 Last visit: 4/20/2022 Posts: 7 Rating: (0)	Tried to initialize the INOUT variables according tothis But no effect..
	Last edited by: NSMCH at: 1/8/2015 11:55 AM
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1/8/2015 12:08 PM	Rate (0)
TomDeWou Platinum Expert Joined: 11/15/2006 Last visit: 5/7/2021 Posts: 1319 Rating: (168)	Which version of TIA portal was it and which FW does your PLC has (and which PLC)? Did you do a SW Rebuild all once? Please make sure you use the latest Version and FW available. Do you probably have other blocks using temp variables which are not initialized? I suggest you make the project smaller and as simple as possible, describe it and sent it to the customer support. Probably they can find a root cause in development.
	Have Fun! TomDeWou
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1/9/2015 10:22 AM	Rate (0)
NSMCH Member Joined: 2/25/2013 Last visit: 4/20/2022 Posts: 7 Rating: (0)	Tom I update my tia portal version to 13.0 upd6, i was still running the original v13.0. CPU firmware was V1.5, I updated it to V1.7. Still no effect... So I started stripping down the code in the FB, untill the problem would dissapear, but it didn't dissapear. I now came to the point where I call an FB with no code in it in OB1. There is only one variable in the FB interface: an 'INOUT' bit. In OB1 I connect a DB bit to it, or a marker bit to it. If I then use a watch table to set and reset the bit (via commando CTRL + F2 and CTRL + F3) the bit still sometimes misses the command, or sets/resets right after I sent out an reset/set command! I must say, the setting/resetting occurs a lot lesser then in the first case. I do the following 50 times in a row: set the bit via CTRL + F2, about 1s later I reset the bit via CTRL + F3. Of the 50 times, at least 1 time (mostly 2 or 3 times) the bit misses the command that I send... Is this normal?
	Last edited by: NSMCH at: 1/9/2015 10:23 AM
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4/29/2016 3:56 PM	Rate (0)
The Helping Hand Moderator Joined: 8/21/2014 Last visit: 9/14/2023 Posts: 733 Rating: (12)	New question published by Tom B. is split to a separate thread with the subject Passing parameters by reference. Best regards The Helping Hand
	My Forum is the place to personalize your profile, track your topics, and maintain content that interests you. Best regards The HelpingHand
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