Project Overview Three ingredients (city water, ingredient QR and ingredient KM) are added in specified amounts by weight to the Mixing Tank. After all the ingredients have been added to the Mixing Tank, the mixture is blended by running the agitator for a given time. When the blending time is complete, the finished product is pumped to the Filling Lines for bottling and final packaging.Detailed Sequence of Operations To begin a new batch, the operator will verify that the “SYSTEM READY” pilot light is on and that the Mixing Tank is ready to receive ingredients.The operator will then press the “START BATCH” pushbutton to begin the batching process. No further operator input is required.The “SYSTEM READY” pilot light will turn off.Automatic valve AV-CW will open. The “ADDING WATER” pilot light will illuminate.The state of AV-CW will be verified by limit switch LS-CW2. If LS-CW2 is not made within 2 seconds after the valve was told to open, a fault will be generated and the system will shut down. The pilot light “SYSTEM FAULT” PL2 will illuminate indicating that a fault has occurred. |
Excerpt – “PLC Programming with RSLogix 5000”Inserting a BranchWe need to “wire the contact” in parallel with the start button. We do this with a branch instruction. Drag the Branch tool button and place it on the marker between the System Enable bit and the Start Batch bit. Click on the blue section of the branch and drag it to the target to the right of the Start Batch PB1 instruction. As you are dragging, it looks like this. Release the mouse button and the branch will appear around the Start Batch bit. Click and drag the XIC (eXamine If Closed) tool button from the User menu to the left side of the new branch. We want this instruction to be tagged “SystemBatching”, just like the OTE in this rung. There is a quick way to do that. Just click and drag the “SystemBatching” tag name from the OTE in this rung to the new instruction. This is called a latching rung. If the SystemEnable bit is on, the SystemBatching bit can be latched by momentarily pressing the Start Batch pushbutton. The SystemBatching bit will stay on and the rung will remain latched until the Stop Batch pushbutton is pressed or the SystemEnable bit goes off. |
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