adccommunitymod (AutomationDirect) asked a question.
Created Date: February 06,2009
Created By: techphets
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Hi, How would you suggest creating a state machine in Lookout Direct? I 've had a few circumstances where this would have been helpful in the past. I'm currently using a DL 205/250 PLC program which is configured in Lookout. The Lookout app provides a means for the end-user to program the PLC on a basic level, setting timer values, output conditions, total number of program steps, number of loops, and voltages. Each program step turns outputs on for a set amount of time then repeats if necessary. The program data entered by the end-user is stored in a multiplexed data table. After one program completes, the next program is called up through the data table. This has been rather reliable but not without its bugs. I think one of the bugs may be caused by the PLC scan being at an unknown rung when the data table switches to a new program. Using a state machine I could place the PLC in a hold mode (turning off main stages), wait for confirmation, switch the data table (updating the data members inside the PLC), wait for confirmation (perhaps just a delay of a few seconds?), then switch the PLC back into run mode by turning stages back on. Thoughts?
Created Date: February 06,2009
Created by: KPrice
techphets, what we do to "pause " the PLC from progressing through Stages to control states of the machinery, is to have the PLC progress to a Stage when the operator must do something (close a lid) or enter values. In this "wait " Stage, we have (1) contact (pushbutton in Lookout) to JUMP to the next Stage. When this "wait " Stage is active, a message appears on Lookout: "Waiting for Operator to close lid and acknowledge ". A button appears under the message that the operator presses after closing the lid (for example). This button tag will then cause the PLC to JUMP to the next Stage. Hope this helps.
Created Date: February 07,2009
Created by: Jim Besselman
techphets;
Have you explored the sequencer object. You might be able to use this as the core of your state machine. I have used this with good success to emulate a mechanical time clock that allows the user to create a schedule for controlling equipment. While the schedule has lots of switches and states it only uses one I/O point(word). One caution, you may need to make provisions to initialize the sequencer in the event of a computer crash.
Created Date: February 06,2009
Created by: techphets
Hi,
How would you suggest creating a state machine in Lookout Direct? I 've had a few circumstances where this would have been helpful in the past.
I'm currently using a DL 205/250 PLC program which is configured in Lookout. The Lookout app provides a means for the end-user to program the PLC on a basic level, setting timer values, output conditions, total number of program steps, number of loops, and voltages.
Each program step turns outputs on for a set amount of time then repeats if necessary.
The program data entered by the end-user is stored in a multiplexed data table. After one program completes, the next program is called up through the data table.
This has been rather reliable but not without its bugs. I think one of the bugs may be caused by the PLC scan being at an unknown rung when the data table switches to a new program.
Using a state machine I could place the PLC in a hold mode (turning off main stages), wait for confirmation, switch the data table (updating the data members inside the PLC), wait for confirmation (perhaps just a delay of a few seconds?), then switch the PLC back into run mode by turning stages back on.
Thoughts?