Intergers bits

ok. i know intergers get sent to PV's. how do they get there if they are not outputs? If i have one production line and one PV, will all the interger files be sent to that one interger address; maybe like, all will be sent to N:12/*? that will leave only 16 messages that can go over that one, so how will maybe 32 different messages be sent from the the PLC?

By "PV", do you mean an Allen Bradley Panelview operator display panel?

yes, i am talking about the panel view in AB. such as the 1000e or the 1400e

Each PanelView has a certain number of Tags. Tags are PLC memory locations that are shared with the PanelView. Once a Tag is defined, it allows the PanelView to monitor and change PLC addresses. The limit on how many Tags can be used is dependent on the model of the PanelView, and on the programming software.

Here is a sample of a list of Tags from a Panelview program.

The objects on the display are programmed to ask for information from the PLC via the communication link. In response to requests the PLC will supply the contents of any PLC memory, not jsut N registers.

ok. so Lancie1 and bernie carton, the tags that the panel view may be looking for might not just be and interger it can be lookinf for bits also?

They can basically look at any memory location in the PLC.

I take it that any memory location can be anything being inputs, outputs, bits, intergers, etc.... My other question was if it is only one panel view will all intreger addresses be just for that panel view...lets say, whereever I see an interger address I can assume that it's for the panel view?

That depends--

Integers can be used internally by the PLC or by analog devices connected to analog cards in the PLC chassis or by anything else communicating with the PLC.

I can assume that it's for the panel view?

Click to expand...

This tends to show that there may be a basic misunderstanding in this process. The display asks the PLC for information and the PLC replies.

Here is a 'read' transaction put in people terms. The exact sequence and contents vary by the method of communication.

Display - "Hi there PLC. Can you give me the value which is as N7:4?"

PLC - "Certainly Display, the value at N7:4 is 42"

Display - "Thank You"

Sometimes a display page shows multiple items which are close together in memory locations. So something like this happens:

Display - "Hi there PLC. Can you give me the values which are in N7:10 through N7:19?"

PLC - "Certainly Display, the values for N7:10 through N7:19 are 12, 72, 183, 34, 519, 3, 22, 162, 9823 and 7640"

Display - "Thank you"

The display can also change values in the PLC:

Display - "Hi there PLC. I would like to change the value in N7:53 to 529"

PLC - "OK Display, I have changed the value in N7:53 to 529"

Display - "Thank you"

Actually the PLC has NO IDEA of the nature of the requesting device. The requester could be another PLC. It will respond to any properly formed request. On some communication types, for example Ethernet, multiple devices can communicate to the PLC. The nature of Ethernet (and other communication types) is that the request is tagged with the identification of the requester (IP) and the reply goes back to that particular requester.

I hope this helps.

Bernie,

Your PLCs obviously are much more polite and speak better English than the ones I have used. Mine say things like, "here you go, sucker. I hope you choke on it. And lots of luck figuring out what happened during that last scan..."

Lancie1 said:

Bernie,

Your PLCs obviously are much more polite and speak better English than the ones I have used. Mine say things like, "here you go, sucker. I hope you choke on it. And lots of luck figuring out what happened during that last scan..."

Click to expand...

Or...

Display - "Hi there PLC. Can you give me the value which is as N7:4?"

PLC - "You have to ask me nicely"

ok cool. now if i had a Panel View let's say a 1000e and i loggd on to it and saw that the display is asking for a value of 42 from N:13, and i guess once the Panel View gets it it will say a display of,"hey operator get your head in the game". Can i change what the value of 42 will say to,"hey operator your doing a good job"?

Actually many displays have message controls which you can set up such that certain messages are triggered for display by conditions, like a number in a register. In the software to set up the display look for 'Message Display' or something like that.

WOW. Thanks.