PC to control PLC input logic?

rooney

Guest
R
Hi everyone,

We all know how powerful and stable the PLC works in our manufacturer. I am getting more involved in PLC projects and maintanance.

I would like to ask everyone whether a PC can be used to control the PLC input logic? My notion is having a user interface so that user can click directly on the software to run the outputs. Another idea is to use a touch screen monitor. I understood this method is widely used but could anyone gave me some suggestion how to work this out.

thank you.

Rooney
 
Hi,
When using Allen Bradley Plcs you can use RS View to configure buttons on a computer screen to do various function by clicking on the button with your mouse. We use this idea to start and stop machines etc. I don't know if this is what you mean.
Mal
 
rooney,

Your question is a little confusing, but I think what you want is an HMI or SCADA system.
My favorite one is citect, for more info see www.citect.com
There are also others available such as wonderware and winCC, for example.
With this software, you can use a PC to view all inputs and outputs, and even internal bits. Generally, you cannot use it to directly write to PLC inputs. It is also not advisable to write directly to outputs, although this can be done. Generally you write to internal bits, this allows you to control motors, other outputs and devices in manual. It also allows you to do sequence starts and anything else you could do with a push button.
There are also touch panels that will do the same thing and are available from most automation suppliers.

If you must write to inputs, say for simulation purposes, these are actually some software packages available. I think one is called plantsim or maybe simulink, but I can't actually remember the name. It was a software package a previous employer used to simulate his entire plant for testing and training purposes. It consisted of a PLC with only the CPU and a couple of ethernet cards. One ethernet card was hooked up to the simulation PC, which simulated the IO.
The other card was hooked up to several SCADA PCs for operator training. The system was run using both wonderware and citect on both modicon and allen bradley PLCs.

Hope this answers your question.

Doug
 
1. For local control use Operation panels as PanelViews in AB-world.

2. For data table (as Excel-Sheet) some Scada could be enough for PC and Scada applications need some Service process to datahandling for PLC as OPC-Server includes in RS-Linx.

3. For SQL database where are relations, use VBasic and OPC-Server if you can. One OLE-DB/ADO control can insert, update and delete records and you maybe need only one Basic Command in you application.
If you do it in Scada developper, you will need hundreds of script rows and you must learn its syntax. Probably you can do it in couple of days if you are familiar with VisualBasic. Think what cost Scada developer, run-time license and what else you neet bay for that.

scada.jpg
 
If you are trying to use a PC or Operator Interface (OI) to "trick" the PLC into thinking an input is on, you will have some trouble with most brands. The best way is to have the input set a "flag" coil to indicate that the input is on. Then replace the input contact everywhere in your program with the "flag" contact. You then use the PC or OI to set another bit in parallel to the input to trip this flag bit. Make sure you don't compromise safety by having the PC override a critical real world inputs.

Code:
|
|    X1
|  RealInput_1                Input_1_ON
|----| |----------+-------------(C1)
|                 |
|    C71          |
|  PC_Input_1     |
|----| |----------+
|
 
You can try Wizcon or citect or..HMI..

Let try some Scada software such as Wizcon..Ciect
or small and cheaper HMI called Infilink at : www.kep.com

I post some picture about Wizcon that we use in our Lab to control
our instrument demon. Station.(Level)

Platootod
:D
 
picture missing

I am sorry for picture ..(What wrong with me today..so sorry for everybody.)
We use Wizcon to control Level Station in our Lab with B&R plc...

Platootod

level by wizcon.jpg
 

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