Beginner question: Can PanelView alter values in a PLC?

I have just now started learning about PLCs. I
have done a lot of procedural programming, but
am new to programming using Ladder Logic.

I have read a couple of books, and have learnt
a lot by looking at

http://www.geocities.com/plc_guide/index.html

Now trying learn more by trying to understand a real program. In that program there are comments such as RESET_UNIT_PV, etc. which seems to set/unset one of the bits in the B2-file.

I have not yet looked at PanelView, so i am not
sure how this works. Can panelview modify
bits on a PLC (possibly by writing over the
network)?

This is program written for SLC-500 series of
processors. It is very much possible that that
is exactly what PanelView is for! It is just
that I have not gotten around to looking at it
yet. So far i only aware of I and O data files
as a way of doing Input/Output.

I apologize if this is too much of beginner quesion and is not appropriate in this forum.

Thanks!

--Raghu

An operator interface (O/I) or human machine interface (HMI) as it is sometimes known, is generally used for two purposes. The first is to display operating status, diagnostic information, and alarms for operator use. The second purpose is to do what you are asking - allow the operator to manipulate bits and/or register values to adjust or control the operation of the PLC and the system. Most HMIs have the ability to configure the screens to write information or bits directly to the PLC over the communications link. Manufacturer's have various limits and techniques for doing this, and you need to get into the HMI configuration software instructions for details.

Incidentally, PanelView is Allen Bradley's trademarked name for their brand of HMI devices, and not a generic term.

This is program written for SLC-500 series of
processors. It is very much possible that that
is exactly what PanelView is for! It is just
that I have not gotten around to looking at it
yet. So far i only aware of I and O data files
as a way of doing Input/Output

Click to expand...

Indeed, the panelview, as all operator interface devices is meant to replace hard wired devices such as pushbuttons, pilot light, gauges etc. for collecting and displaying to/from the operator.

They replace input devices by writing data (bits, integers, floats,a nd even strings) to the processor's data table in response to operator input (i.e. pressing an F-key or entering a numeric value)

They replace output devices by scanning a processors data table and displaying information in a manner useful to the operator (sometimes a word, sometimes a color, other times a number or analog gage is displayed). In more sophisticated systems the operator interface will display an animation of the machine an/or show pictures or a real time display from a camera watching a process.

In your message you probably meant the B3 file. In AB SLC/500 processors, the first 8 files have defined types which cannot be changed. File 2 is the system status file and is designated S2.

It sounds like you have an existing application. If starting from scratch, I would define other files specifically for interfacing to the Panelview. I.e. B13 for Panelview inputs, B14 for panelview outputs N17 for panelview integers, F18 for panelview floating point values. (This may be a little beyond your knowledge base right now but you'll soon see what I mean )

Hope this helps

Panelview

The PLC looks at the Allen-Bradley Panelview as just another rack(s) in the system. If your question is "can a Panelview alter or change data files in the PLC" the answer is YES, as inputs to the PLC.
The PLC can communicate with the Panelview over remote I/O, Data Highway +, Ethernet, Discrete, BTW/BTR, and MSG instructions.

Good Luck