Navigation
Rating 
Thanks 9
| 3/21/2014 5:07 PM | |
|
Posts: 7 Rating:
|
thank you a lot Marcjan, I'm grateful |
| 3/21/2014 6:30 PM | |
Joined: 7/7/2010 Last visit: 11/15/2024 Posts: 15402 Rating:
|
I know I came across harshly, but you have to understand we get posts all the time where you can tell the only goal the poster has is someone to do their work for them. They have not tried anything, read anything, and are giving you the slightest possible amount of detail in hopes of getting a complete working demo of something they should be doing for their jobs. As Marcjansaid, we provide these posts free of charge while doing our regular jobs in hopes some day when we are as stumped or stuck as the person we are helping that the favor is returned. In my case, I only started using S7 PLCs with the s7-1200 plc family a few years ago and needed to get up to speed quickly - much like a student. I did my best to understand the Siemens way and needed many nudges from the forum participants here to help make progress. Nothing in your posts up to the point where you said you were a student made me think you were a novice to control work. So I answered in way that made sense from that perspective, yes, too harshly, and for that, I am sorry. It bugs me when I do that, but this is the internet and we cannot see your face, feel your expression, gauge your response, and in general enhance the communication like we can in person. We guess, and often - at least for me - guess wrongly. I still say there is no definitive guide on how to use OB100. I have written entire programs without a first-scan set of logic. However, if I did not have that option of knowing the plc just restarted and have to figure it out by some odd control technique, I would probably be unhappy about it. It gives you the option to tell your sequencers and state machines to reset to an unknown state. From the unknown state, your sequencers can analyze your control inputs, establish a semi-known state, and then prompt the end-user in some way they need to reset the system. If your project is to program something to build say "erect a case" (build a cardboard box from flat stock), you have a lot of cylinders that may be in mid-position due to some mechanical jam up. If this is likely to happen, your control scheme may include sensors to detect a jam, or a bit that is retained during power outages or plc restarts can save that jammed state, and on restart, use the jammed state saved from the end of the last plc logic before plc off or restart and establish proper startup. Perhaps a screenshot of your concepts so far could help us help you further. We really want control engineers to do be aware of best practice and strive to use them where they make sense. I gave general answers thinking you had been doing controls work for a long time. Hopefully you can understand we really do want to help. It helps us all when we help each other. |
|
science guy |
|
This contribution was helpful to
|
|
Follow us on