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Function block EN input

Created by: Flomaster at: 12/16/2010 8:24 AM (10 Replies)

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12/16/2010 8:24 AM	Rate (0)
Flomaster Posts: 65 Rating: (2)	Hi all! I need to create a function block without EN input and ENO output (such as TP, TON and others). I want to use my own inout IN input and OUT output, which will be placed directly on a network. But I down't now how to create such FB. By default new FB has EN and ENO, but I don't see this input and output in "Interface" tabsheet of FB. As alternative, I can use EN and ENO, but how to get access to this variables? I don's see it in variable s list of FB. Has someone any ideas how to do it? Thanks!
Flomaster Posts: 65 Rating: (2)
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12/16/2010 10:46 AM	Rate (0)
Guus Posts: 20 Rating: (1)	At the top of your FB you'll see 'interface' pull it down, fill in you variables, use them in your FB with a # before your variable. EN and ENO will always be attached to your FB. Greetz
Guus Posts: 20 Rating: (1)
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12/16/2010 10:59 AM	Rate (0)
fritz Diamond Member Joined: 10/7/2005 Last visit: 11/6/2024 Posts: 3026 Rating: (1056)	Hello Flomaster the "EN" and "ENO" connectors for FC and FB's exist only when the Block is called in LAD or FBD view and are used to allow conditonal call's of Blocks (via EN) as well as "downstream" cascading of Blocks (via ENO). "EN" is handed entirely outside the called FC/FBand equates to a conditonal Jump (via the STL JNB command. Test this for yourself by calling an FC/FB conditionally in LAD/FBD and then switch the view to STL). Bottom line for "EN": It does NOT exist inside the FC/FB, hence you won't see it in its interface. Whiel "ENO" also does not exist as a "visible" Parmater of the FC/FB, its status/value depends on the the BR bit in the Status word andcan/may be manipulated via certain instructions inside the FC/FB. You can find out more about the above inTHIS link below and also in the Ladder Logic (LAD) for S7-300 and S7-400 Programming manual (search for ENO, the FBD manual will have the same info). I hope this helps
	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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12/16/2010 12:19 PM	Rate (0)
Flomaster Posts: 65 Rating: (2)	Thank your for information. But why TP, TON and so on has not EN and ENO in FBD and LAD?
Flomaster Posts: 65 Rating: (2)
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12/16/2010 1:46 PM	Rate (0)
Chilly_Garfield Posts: 316 Rating: (37)	Hi Flomaster, SFBs and SFCs havethe parameters EN and ENO. See the attached file. Attachment TON.GIF (1069 Downloads)
Chilly_Garfield Posts: 316 Rating: (37)
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12/16/2010 1:57 PM	Rate (0)
Flomaster Posts: 65 Rating: (2)	Sorry, but in Step7 Basic there are no EN and ENO parameters in TP, TON and TOF function blocks.
Flomaster Posts: 65 Rating: (2)
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12/16/2010 4:02 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 11/6/2024 Posts: 15385 Rating: (2443)	Flomaster Sorry, but in Step7 Basic there are no EN and ENO parameters in TP, TON and TOF function blocks. I have several FC/FBs in LAD with ENO functional. I use RET with a value of True or False to set ENO ON or OFF. This is like an exit from a computer programming language somewhere other than at the end of the subroutine. It's working for me. Perhaps others have yet to discover this?
	science guy
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12/17/2010 12:34 AM	Rate (0)
Flomaster Posts: 65 Rating: (2)	huggy_d1 I use RET with a value of True or False to set ENO ON or OFF. It's a good idea, but in my project using of EN is more important for me. I try to implement triggers as function blocks: R_TRIG to detects a rising edge and F_TRIG to detect a falling edge. And I want to use EN or my own input of FB, placed on network, to detect input signal (TRUE or FALSE). Somebody knows how such mechanism implemented in timers (TP, TON, TOF)?
Flomaster Posts: 65 Rating: (2)
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12/17/2010 12:17 PM	Rate (0)
fritz Diamond Member Joined: 10/7/2005 Last visit: 11/6/2024 Posts: 3026 Rating: (1056)	Hello Flomaster first of all I must admit that I missed the fact that you (quite correctly) posted your question in the Step 7 Basic forum and that I (somewhat incorrectly) offered an explanation and links that relate to the "real" Step 7. Having said that, the EN and ENO mechanism is fortunately the same for both so I hope it helped in clarifying a few things anyhow. As for this question: Flomaster ...but in Step7 Basic there are no EN and ENO parameters in TP, TON and TOF function blocks. I must say that it is a jolly good question and something I hadn't even noticed yet, nor would be able to give you a definitive reason for it. Personally, I quite like it though, since a Timer is a Timer and I can't see any need for an EN/ENO mechanism for them. Since Step7 basic does not have the"S5 Timers" (which didn't have EN/ENO), I wonder if Siemens wanted to simplify the Step 7 Basic IEC Timers too. This is agood thing as far as I'm concerned as it is rather annoying in the "real" Step 7 when you drag for example SFB 4 (TON) IEC Timer into a rung and the preceding logic"latches" onto the EN input instead of the Timer starting "IN" input where you want it to be. Anyway, if you really must have an "EN" connector and an "ENO" output, nothing will stop you from embedding for example a TON Timer inside an FB as a Multi-Instance call,link the TON's parameters to the FB's IN/OUT parameters. handle the ENO of the FB as you see fit and you got yourself a "Timer" FB which will have EN and ENO (but will unfortunately have lost the multi-Instance capability which Step 7 Basic V10.5 does not support for user created FB's. I think V11 will accomodate thsi though). I hope this helps
	Last edited by: fritz at: 12/18/2010 1:06 PM 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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12/17/2010 4:11 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 11/6/2024 Posts: 15385 Rating: (2443)	Ok, I think I understand what you want to do. No, you can't do it exactly like you want because the FC/FB logic will not run without EN being set to ON. You can use a bit to follow the status of logic you want to monitor, then add a parallel rung within the same network that uses that bit as an input to the FC/FB. Then you can leave the FC/FB running all the time, monitor the status of the logic with the bit at the input, then handle the triggering as you see fit. The key here is for your FC/FB to notice anything, the EN must be on or your FC/FB logic will not even be run. Hope that makes sense.
	science guy
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