12/16/2010 10:59 AM | |
Joined: 10/7/2005 Last visit: 8/9/2024 Posts: 3016 Rating:
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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 |
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12/16/2010 12:19 PM | |
Posts: 65 Rating:
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Thank your for information. But why TP, TON and so on has not EN and ENO in FBD and LAD? |
12/16/2010 1:46 PM | |
Posts: 316 Rating:
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Hi Flomaster, SFBs and SFCs havethe parameters EN and ENO. See the attached file. |
12/16/2010 1:57 PM | |
Posts: 65 Rating:
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Sorry, but in Step7 Basic there are no EN and ENO parameters in TP, TON and TOF function blocks. |
12/17/2010 12:17 PM | |
Joined: 10/7/2005 Last visit: 8/9/2024 Posts: 3016 Rating:
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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:
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 PMCheers |
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