PLC Newbie

[ExtremeIntegrations]

This is good information, thanks. I do have the FP-X C14R. I bought the small 8 port just to keep it simple to learn with. You are correct that support seems to be hard to come by. Since I'm a contractor to this company I must succeed in this project so I'm guessing there are many late nights ahead

I think the most difficult part is learning the development environment and understanding what I'm looking at and each part. For example I've been at this for 3 days and I have NO idea what POU even means.

My client is pretty cheap so cost was the factor that drove us to the Panasonic. I think if I can start to understand the workings of the PLC then I should be able to catch on quickly and make this happen.

Most lower-end PLCs don't have multithreading capability; the entire program is repeatedly scanned over and over. But since the processor is so fast, this is generally not a problem unless you have a very large program and/or complex math. Many PLCs have interrupt capability that allows you to execute specific code more frequently if necessary.

I do have some experience with the Panasonic/Matsushita PLCs. The FP-X series in my case. These are very capable units but the FPWIN software does take a little getting used to. Have you gone through the First Steps Demo? I have found the online help to be fairly thorough. The structured text commands are all documented there, but not organized well. The AFPX-C14R on my bench is running a fairly small program with a scan time of <1 ms (not bad). If you add your POU's to the "Programs" task in FPWIN, they will scan repeatedly as fast as possible. Look in the PLC Status window (Monitor menu) while online with the PLC and you can see the current scan time.

If you're just getting started with PLCs, I wouldn't recommend the Panasonic. It's a powerful unit to be sure, but you won't get much support from online sources (like this website). Choose Allen-Bradley, Siemens, or Automation Direct and you'll get much more help -- assuming you ask the right questions

 

[kolyur]

Some tips:
POUs are "Program Organization Units", basically just programs. You can write POUs in any of the five PLC languages. I would suggest ladder for control-type logic and structured text for any math or calculations. Alternatively, you could just make one POU to do everything. Every POU you create is automatically added to the "Programs" task, meaning that they will run sequentially and repeat as fast as the processor allows. You can move individual POUs to the interrupt tasks if you need different operation. If you want to use the I/O pins, create global variables and assign them to X0, X1... (inputs) or Y0, Y1... (outputs).

If you have any specific questions, post them here. I'm no expert with FPX but I'll give you my best guess.

 

[ExtremeIntegrations]

Ok well here goes with the question. I'll probably start a new specific thread also.

I have 33 machines in my plant. Currently I'm only going to deal with 8 since my test PLC only has 8 inputs. Each machine has a sensor that sends a signal when the machine is open (usually 2-3 seconds) and when it's closed (usually 20 seconds). My task is to determine the milliseconds between the times of "open" to the next "open" signal.

While these calculations are happening, somehow I need to get this information back to a computer so I can record into my database. I have built a webservice that accepts HTTP post so if there is any way possible I'd like the PLC to submit the data to the database via HTTP. If that is not an option, I would like to read the data from the PLC from a computer set to monitor the PLC.

I know I'm asking for a lot from a PLC but now that I'm committed I have to come up with something to make this work I opted for a PLC because they are industry standards and I didn't want to be stuck with a proprietary piece of hardware which we have now.


What is your opinion?

Some tips:
POUs are "Program Organization Units", basically just programs. You can write POUs in any of the five PLC languages. I would suggest ladder for control-type logic and structured text for any math or calculations. Alternatively, you could just make one POU to do everything. Every POU you create is automatically added to the "Programs" task, meaning that they will run sequentially and repeat as fast as the processor allows. You can move individual POUs to the interrupt tasks if you need different operation. If you want to use the I/O pins, create global variables and assign them to X0, X1... (inputs) or Y0, Y1... (outputs).

If you have any specific questions, post them here. I'm no expert with FPX but I'll give you my best guess.

 

[TheStarr]

This may go nowhere but... What controls the press currently and why can't you communicate directly with it?

You never said what type of press or what controls exist.

If they are PLC driven, then it is likely that you could communicate directly with them using KepWare or some other third party software and then manipulate the data in VB.

I am guessing they are older relay logic or you already would have gone this way, but it is worth asking.

 

[TheStarr]

One more question. Your a computer programmer, why not use a pc and a dio card?

Like this: http://www.omega.com/ppt/pptsc.asp?ref=CIO-DIO48&ttID=CIO-DIO48&Nav=

You could do the whole plant with one PC and a VB app.

 

[ExtremeIntegrations]

Yea these are older machines (extruders). Nothing fancy on these things. They have minimum electronics and a manual dial to speed up or slow down the machine itself. I sure wish there was some way to communicate with them. Plus we have several different manufactures of extruders. They all come from the Flinestone age.

This may go nowhere but... What controls the press currently and why can't you communicate directly with it?

You never said what type of press or what controls exist.

If they are PLC driven, then it is likely that you could communicate directly with them using KepWare or some other third party software and then manipulate the data in VB.

I am guessing they are older relay logic or you already would have gone this way, but it is worth asking.

 

[TheStarr]

Did you see this post? I squeezed it in while you were typing.

One more question. Your a computer programmer, why not use a pc and a dio card?

Like this: http://www.omega.com/ppt/pptsc.asp?ref=CIO-DIO48&ttID=CIO-DIO48&Nav=

You could do the whole plant with one PC and a VB app.

 

[ExtremeIntegrations]

Thanks, Yea we tried a simular product but encountered troubles if the signals were at the same time. The product we had wasn't fast enough to monitor all 33 ports because it scanned linear. While it was scanning it would get to port 20 and at that moment port 3 would send a signal and we'd miss the signal due to speed.

This is why I opted to go PLC route because they are fast.

Did you see this post? I squeezed it in while you were typing.

 

[pocketooth]

Since you are a software developer, 1st. check panasonic's web site to see if they have communication server in ActiveX. If it does, all you need to do is getting PLC data from activeX and sending the result via HTTP post. If you can not find any, then you will need to send the output to the communication port (RS-232) and connect to a PC. From PC, you should know what to do.