diving in head first

[Jody M]

As a relative newby myself my advice (18 months) would be first read every post on this forum. second by a Automation direct DL-06 and download there free direct soft 100, download or buy the manual and read it cover to cover twice. Then keep it next to your computer while you are working with your projects. I found simply entering there example programs helped me with logic flow. Good Luck Oh and did I say read this forum these guys helped me through my biggest problem I had, just getting started writing my projects.

Jody

 

[Terry Woods]

Hi, Jody...

Welcome. I see you've been here for a bit. I assume by your name and the US Flag that English must be your primary language.

However, please, just as a courtesy, please preview, please re-read, and maybe spell-check your post before posting.

DON'T EVEN LET THIS CHASE YOU AWAY!!!!!!!!!!!!!!!!!!!!

Think about it... if you are working for someone that is more literate than you, what do you think they would think about your basic intellect? Most of us here are, at least, somewhat literate. Just consider and do what you need to do to project the image that you REALLY want to be seen! Consider some of the writing that YOU have found objectionable.

At the very least, thanks a bunch for not using thumb-txt.

Actually, spelling is not the issue... rather, sentence structure.

 

[tir38]

Terry, i completely agree with you its just i didn't know that sensors would cost more than basic switches. What do you think about this system: ebay auction. This seems like everything (except a manual and some input/output simulators) that i'd need to get started.

I have a lot of experience in object oriented programming with Matlab and ANSYS, but i'm not sure how logic programing differs from object oriented programming. I've also done some BASIC coding for the HC11 microcontroller to operate a robot I built.

 

[Terry Woods]

That system looks fine. And manuals are available on-line, FREE!

Regarding the difference between typical computer programming and PLC programming, the primary difference is in the way that the outputs (control_relay-bits and real output-bits) are controlled and maintained.

In a typical programming language, non-PLC, once you turn a bit ON it stays ON until you explicitly turn it OFF, or power-down the system. While the processor is running, there is no default-state for any bit... that is, any bit in RAM. Of course, once a bit is written to the hard-drive, it stays as is until over-written.). PLCs do everything in RAM. There's no way that a fast process could afford to wait for a disk-read to carry on.

In a PLC, generally speaking and while ignoring SET/RST, the default-state of an output-bit is OFF! That is, on every scan, if there is no reason to keep a particular Output-bit ON, then that Output-bit will go to the default-state (OFF).

There is an exception to this... some PLCs support an Output-OFF as opposed to the typical Output-ON. In that case, the default-state is ON.

To maintain an Output-bit being ON, you have to do so, EXPLICITLY, from scan to scan.

As I said, this ignores the SET/RST issue. In the case of a SET Output, if a rung does not support the Output-bit being SET (ON), then that rung WILL NOT cause the Output-bit to go to its' typical default-state, OFF. It WILL NOT cause the Output-bit to go to ANY particular state!

Likewise, in the case of a RST Output, if a rung does not support the Output-bit being RST (OFF), then that rung WILL NOT cause the Output-bit to go to any particular state.

In the case of SET/RST, you don't have to explicitely maintain a bit. BUT, you do have to EXPLICITLY change the state of the bit!

The PLC SET/RST Outputs are more in line with how regular computer programming is conducted.

Finally...

--| |-- is a question... Is the particular Bit ON?

--|/|-- is a question... Is the particular Bit OFF?

Clear as mud?

 

[just_lionel]

Hi Jason,

Welcome to the forum. The site if chocked full of useful information. Some of it maybe over your head right now, but alot of it is still usefull.

We have a great community of members up here that can provide more information and answer about any question you may have. I too was in your boat but I jumped right in and sank for a little while. I posted sample programs up on the site and they did a good job ripping them down, but I did learn alot from their comments and suggestions.

If I can suggest one thing; I suggest you take it slow. It can be tempting to jump in head first, but you can get easily discourged/fustrated. Learn the XIC/XIO OTE TON, TOF, etc etc, before tackling larger commands.

Listen to Terry, he is full of information. Another person is Ron Beaufort, do a search on these two people and learn quite a bit. A few others are rsdoran, Lancie1, elevmike, etc (These people have helped me out a ton). They don't mind helping as long as you show that you are trying.

Sincerely,

Lionel

 

[elevmike]

Just to note: At the time of the post the ebay system was up to $182.00.

Dont buy it.

For another $40.00 you can get a brand new AD DL06 with highspeed inputs, pulse outputs, more memory, a wider range of options on the 2nd serial port, and a full instruction set. The DL06 much much better learning platform that will take you through the ENTIRE instruction set.

 

[Terry Woods]

Mike said...
"For another $40.00 you can get a brand new AD DL06 with highspeed inputs, pulse outputs, more memory, a wider range of options on the 2nd serial port, and a full instruction set. The DL06 much much better learning platform that will take you through the ENTIRE instruction set."

WELL... there ya go tir! Do as Mike says! You won't know how glad you should be for having done so, but, believe me, it is a GOOD THING! GO FOR IT!