PV600 numeric input options

Hey fellas,

It's been a very long time since I worked on our PV600 terminals with PanelBuilder and have a question. I haven't had a chance to dig into it yet, so maybe I'm over thinking this and there's a simple answer.

I have a PV600 set up as a remote IO rack for a PLC5. The PLC5 is set up with a BTR/BTW pair to handle integers for operator input and displays. In the PV I have numeric inputs which are read by the PLC by the BTR. This setup works just fine for purely operator inputs. Now they want me to manipulate one specific input value in the PLC logic, outside the operator's control. The problem is that I cannot change the value of that integer because the BTR keeps overwriting it.

Is there an alternative way to get that number from the PV600 to the PLC outside of the BTR like writing directly to an N7 word that's outside the block transfers touch or am I stuck using the BTR? Would be nice to have a means to input a number on the PV but only have it write once to the PLC. If I must use the BTR to get that numeric input from the PV, then I'll have to do some fancier logic to use either the PV value or my new value.

Any help or advice you may have would be very much appreciated.

With the PV600 on RIO, you must use block transfers to get any extra data to and from the HMI in addition to its assigned logical I/O space.

So, any values entered by the operator are going to have to go to the PLC via the BTR or the discrete inputs, but you can certainly do what ever you want with that value in the PLC logic (using internal non-BT addresses) and then send the result right back to the PV600 using an address set up for BTW.

If you can describe in more detail what you are trying to accomplish, we can give more detail.

You're on the right track, but the BTR data is always being written so you have to save it to a working register only once. I've used the following technique on all of my RIO PanelView projects. This isn't an issue with serial or any other network since the PV only writes to the PLC register when a setpoint is entered.

In the PanelView numeric entry, use all four tags: Write, Notification, Handshake and Display. In the PLC example, N21 is the BTR file and N22 is the BTW file. Each setpoint requires the two rungs shown, but the all of the MOV to BTW instructions can be replaced by a single COP if the setpoint and BTW registers are in the same order. Entering a new value sets the Notify bit, which turns on the Ack bit in the PLC. When the PV sees the Ack bit turn on, it resets the Notify bit and closes the keypad. This way, the setpoint can also be changed from a SCADA system or by other logic and the PV always displays the current value.

Thanks Mike. I thought we'd have to do something along those lines.

OkiePC, here's my application in a nut shell...
> Operator sets line speed based on his needs via input on panelview. He's driving the bus. Been like this forever.
> Now ops wants us to modify line speed based on a particular product dimension. Sometimes operators forget to modify line speed when they begin running this specific dimension product which results in some grief.

I would recommend using the write tag and display tag as two distinct variables. I think this is what Mike was illustrating in his ladder example, but his PB32 screenshot does not show anything in the display field.

The Write tag will need to be in one of your BTR groups (since it gets Read by the PLC), and the Display tag will be in on of the BTW groups so that the PLC can write to it.

Then, in the PLC, do whatever you have to do in order to achieve the goal of restricting/modifying the actual value used that ends up controlling line speed. Then copy/scale that result to the display tag. Actually, the line speed will always (unconditionally) need to be copied/scaled to the display tag. This way the screen will show the line speed when the operator changes it and when it gets changed by PLC logic.

Bottom Line: Always show on the HMI the line speed which is actually in use. If the operator entry is out of range, or otherwise overruled by the PLC, the display object will help the operator understand that. Sometimes with the Panelviews, you have to take extra steps like this to keep the HMI telling the truth.

You can't do that if you don't use the display tag...the screen object will show the write tag and the value last written if the Display tag field is left blank.

As for the notify and handshake tags, sure you can use them to control when the PLC does the range checking on a user input, but you will find that you may want to use them for all of your entry obejects in order to maintain consistency. If you leave the handshake and notify tags blank, the HMI will use the Display tag to populate the data in the Entry Object. If you leave the display tag blank, it will use the last value that it wrote to the write tag (which may be invalid).

I generally avoid using the handshake and notify tags unless there is some PLC intensive math that I want to condition with the notify bits...but when I use them once, I use them everywhere (lotsa work and extra tags). I have one application that is very String File intensive, so I use the notify and handshake bits on all the entry objects in that application just to keep the SLC scan time as low as possible.

With the PV on RIO, simply using unique address for the display and write tags for entry objects should suffice.

Thanks again for the info OkiePC. Much appreciated.