Order of starting motors.

paulB · Nov 21, 2011

Hello,

I am looking for some advice. This is RS Logix 5000 and Panelview Plus with Factory Talk ME 5.1. There are three motors A, B, and C, which have to start in sequence for example A - first, B - second, and C - third. This order has to be selected by operator. So on HMI screen under each motor start/stop control I have placed three multistate pushbuttons. These multistate pushbutton will write value 1, 2, or 3 to the tag of respective motor. This tag will define, where in sequence start of each motor will take place. Operator will assign start order for each motor, 1, 2, or 3. So far so good. What I am struggling with how to make impossible to assign the same number to two or three motors.
Any suggestion?

bce123 · Nov 21, 2011

use one entry to write a value to plc ie: 1= 1,2,3 2= 231 .......and so on ?

agarb · Nov 21, 2011

Add up the 3 values and check to make sure they equal six?

paulB · Nov 21, 2011

It seems both ideas would work. I've just missed one piece from the puzzle. Each of the motors may be bypassed. In this case controls for this motor will become invisible on HMI screen.

bce123 · Nov 21, 2011

maybe a enable disable for each motor and a selector for sequence

OkiePC · Nov 21, 2011

Drop down list with all possibilities...let them choose the one they like and decode it's behavior in the PLC with a simple EQU...

paulB · Nov 21, 2011

Control List Selector may be solution.

Thank you.

MasterBlaster · Nov 21, 2011

Well, adding the vales and checking for a total of six would allow them all to be #2, so probably not the best fix.

I'd build a display in such a way that a horizontal box represents each pump, and stack them one atop the other. Animate such that you can "select" a box, then click an "up" or "down" arrow to move the pump on the list. The position on the list represents sequence to start. (Top slot starts first, middle slot second, bottom slot third.) That way, no duplication or exclusions are possible.

Bill

daba · Nov 21, 2011

I would make it simple - just have 9 buttons on the HMI to select 1st, 2nd, or 3rd for each pump.

I would not try to do any logic in the HMI at all.

Do the logic in the PLC such that when, for example, Pump B is selected as 1st, the other "1st" buttons are disabled.

Add a Reset button to clear all the selections, and the operator can select 1, 2 or 3 pumps in any order he likes.

A picture speaks a thousand words.....

paulB · Nov 21, 2011

This is very neat. Thank you.

Lancie1 · Nov 21, 2011

What I am struggling with how to make impossible to assign the same number to two or three motors. Any suggestion?

Yes, because you want the operator to be able to change the numbers, then you must not restrict an entry UNTIL all 3 have been entered. Once the operator says that "yeah, I am happy with the 3 numbers as set now" (using a "New Entry Made" button), then the PLC (or you could do this error checking with internal Factory Talk derived tags) checks the 3 numbers to make sure that no two are equal, and that they all are within range (>0 and <4). If an error is found, then a screen warning is flashed and the operator must reenter the 3 numbers and then signal that a new set have been entered by pushing the "New Entry" button.

shawn_75 · Nov 21, 2011

daba said:
I would make it simple - just have 9 buttons on the HMI to select 1st, 2nd, or 3rd for each pump.

I would not try to do any logic in the HMI at all.

Do the logic in the PLC such that when, for example, Pump B is selected as 1st, the other "1st" buttons are disabled.

Add a Reset button to clear all the selections, and the operator can select 1, 2 or 3 pumps in any order he likes.

A picture speaks a thousand words.....

I personally try to do as little logic as possible in the HMI as well. Bubba, while not usually well versed in ladder logic, sure as heck is going to have a much harder time figuring out the HMI code.

It seems that most here would do this in the HMI.

Shawn

Lancie1 · Nov 21, 2011

I would make it simple - just have 9 buttons on the HMI to select 1st, 2nd, or 3rd for each pump.

Hmmm...on a PanelView with limited screen area, button space becomes as precious as gold. Nine buttons will probably take up one whole screen, making it necessary to add another menu button to scroll to this new screen to select the running order for only 3 motors. Different strokes for different folks.

dcooper33 · Nov 21, 2011

Code:

SOR BST LES A_POS 1 MOV 1 A_POS NXB GRT A_POS 3 MOV 3 A_POS BND EOR
(Repeat for all three tags)
SOR NEQ A_POS B_POS NEQ A_POS C_POS NEQ B_POS C_POS OTE VALID_SEQUENCE EOR

Have Numeric Input Enable buttons for each motor on the screen. The operator can enter whatever # they like, but only #'s 1-3 will be accepted by the PLC. In fact, you can set Min 1 and Max 3 in the object properties itself. Then you can have an indicator next to the Input buttons that shows "Valid Starting Sequence Selected" when the "VALID_SEQUENCE" bit is on.

dcooper33 · Nov 21, 2011

Here's a .pdf of what I was talking about.

Cheers,
Dustin

Order of starting motors.

paulB

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agarb

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