Stopping data entry into PLC from HMI

manmeetvirdi

Member
Join Date
Oct 2004
Location
India.
Posts
750
Hi
We have key operated selection switch in a panel on which HMI(MP277) is also mounted.
Is it possible that when this selection switch is in OFF condition the value transfer from HMI's I/O field
to DB's of PLC stops?
Transfering the data from the one location to other when selector switch is in ON position is one way, but gives problem when I/O fields are too many.


This is the requirement of the client, who wants to stop unauthorised data entry in HMI.

Can it be done, say I password protect all the I/O fileds of HMI and when when selection switch is in ON condition, I transfer correct LOGIN NAME and PASSWORD to HMI, after which I/O fields can be accessed.
And when its in OFF condition i activate the LOGOFF function of HMI.
But then where to transfer the LOGIN NAME and PASSWORD?Is it Area Pointer?
Similarly how to activate LOGOFF function through HMI?

Manmeet
 
Last edited:
Can it be done? Sure it can.

On the HMI-tag which is linked to the switch, attach a VB script to the 'Change Value'-event. Example of such VB-script:

If Switch = True Then
Logon(password,username); // Logs on with given username/pass.
Else
Logoff; // Logs off current user.
End

Switch: Switch selection. ON or OFF
password: a TAG containing the password (this part I haven't tested yet)
username: a TAG containing the user name (this part I haven't tested yet)

This is as close I could get with the use of the help file.

It may be what you are looking for, but remember: The IO-fields will still be enabled, operators can still try to activate them, but it will ask user name and pass. After 3 failed attempts the user is blocked. Do not forget that.
 
A simple way would be to buffer the write registers. The HMI is configured to write to one area of memory. When the key swtich is on the PLC copies those registers to the areas of memory actually used by the program. If the switch is off then instead of transfering the buffer area to the working area, the PLC transfers the working area to the buffer, overwriting any unauthorized change, so even though an operator may change a variable, it will chage right back to what it was before.
 
Hi there Jeebs,
I did give try to what you have suggested but some how was unable to make through(probably because you said"this part i haven't tested",a physiological effect)

I had solved the problem like this:
1)goto area pointer put the job mail box ON
2)give some specific address at address column, i gave MW260
3)transfer the 23 to MW260 (when a condition get satisfied) and 9 to mw262, you are done.
Now you can enter to all the password protected I/O fields withouth actually entering USERNAME and PASSWORD


What is 23? It is Job Number, and Job Number 23 stands for the job "User logon" just like 51 stands for "display selection".

what is 9? it is group number which by default comes with Administrators.This you can locate at GROUPS under RUNTIME USER ADMINISTRATION.

Similarly you can log off using Job number 24.

But as you said, if operator keeps on trying to enter correct password and username beyond three times, then you need to plug off the 24V DC supply to HMI to re-enable the password system.

If you goto WinCCFlexible help and type "logon" under "Search" tab you will get what I have just mentioned

Manmeet
 
I would just disable the boxes when the bit is made. I do this all the time so the operator can't make changes while the machine is running. Another way would be to change the visible so they can't see them.
 
CharlesM said:
I would just disable the boxes when the bit is made. I do this all the time so the operator can't make changes while the machine is running.

Disaable the I/O boxes!!Wow how to do that CharlesM??
Not able to figure out.
Romoving visibility is yet another idea,which can be implemented easily but most of the operators are not going to like this.

Can you elaborte on how to disable the I/O boxes.

Manmeet
 
enable.JPG


Visibility.JPG
 
I have a other option. You can use a DB pointer to select which DB it operates on. Here is what I mean:

DB1 is your normal access area.
DB2 is it's copy and every scan you do a block move from DB1-->DB2

Using a internal tag "DB_Select" and script you select between 1 and 2. Then in the Multiplex area you use "DB_Select" to select DB.

User trys to change value and old value is slammed back on.

DB_Select2.JPG


Nick
 
Mindblowing CharlesM

This works wonderfully well, never thought on using this Animation property of a tag for this purpose.
Thanks(y)
 
I have a other option. You can use a DB pointer to select which DB it operates on.

That is another option. I have often thought if I had several machines with one HMI i would use that type of setup.
 
NickB great!

I will give try to this idea of yours.Besides solving this problem it can be used in doing other great things too!!
But what CharlesM has come up with, is exactly what i was looking for, and besides everything else its very neat and damn easy to implement.
 
While we're on tips and tricks

We're using various dropdown menu's all stacked in the exact same location .When the operator selects a format the 'right' dropdown menu becomes visible for that format while the others are hidden.
 
Charles. That idea about disabling the input fields is a good simple idea. I like it.

I am warming to the idea of using a keyswitch instead of the password functionality. I have a few customers that repeatedly gets all users logged off because they enter the password incorrectly 3 times.
 

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