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ScanMeg Backlogscanners
- 1. BackLog Scanners Type MD Light-curtain - and - Type PROX with Remote I/O Block
- 6. Significant increase in lug fill %
- 7. Type MD emitter under transfer chain
- 8. Scanner protected by angled plexi-glass
- 9. Emitter below chain and receiver above at an angle at lug loader
- 10. Emitter at angle with plexi-glass debris cover
- 16. Interface to PC RS232 interface to PC and Windows based programming Rail Mounted in PLC cabinet RS422 input from scanner
- 17. Interconnection wiring Vcc 0 Vdc To Rx+ (Out) To RX- (Out) From Tx+ (In) From Tx- (in) Red Gray White Yellow Green Brown Wire Description & Color 8 5 1 4 3 2 Turks Pin Connector Blue and Pink N.C.
- 18. Language selection PNP configuration window Program Quit button Interface Software Version Global display Cells configuration (viewing only) Save Configuration to file Active Configuration window Configuration window Position Exit Program Minimize window Default Configuration Open Configuration from file Software Interface to Configure Scanner X-axis are outputs from REM-IO module Y-axis show cells from PROX
Editor's Notes
- This series of pictures show the installation at West Fraser’s PIR Division in Smithers, British Columbia. There are four decks from the unscrambler to the lug loader. The MD Backlog Pressure scanners monitor the fill of the decks and the frequency drives control the chains speed. The object is to have the optimum fill and pressure against the lug loader to have a steady flow.
- Increase in lug fill and reduction in hand and back injuries were experienced as a result of the installation. Note that the receivers are placed well out of the way of any boards that might be lifted up.
- The chains automatically speed up depending on the fill on the individual deck thus keeping a steady flow of boards at the lug loader resulting in a significantly higher percentage of lug fills than with manually-fed lug loaders. The PROX takes the guess work out of the equation.
- The emitter is located under the chainway. A plexi-glass shielding at an angle was used to deflect any debris or sawdust on the emitter.
- Note the plexi-glass protection. The scanner itself is waterproof and handles vibration really well.
- The object is to maximize the lumber at the lug loader without over-feeding. The Backlog Pressure scanner controls the amount of lumber on each deck and modulates the flow to maintain a high lug fill. With frequency drives on each deck the chain speed varies to provide a constant flow of boards.
- As a result of the success of the MD scanner we developed the PROX Backlog Pressure scanner. It has both the emitting LEDs and the phototransistors on the same board eliminating the need of having the receiver overhead. In addition we developed a remote I/O block that accepts the information from each individual cell. This provides more information and flexibility to the design of the system. The remote I/O block, REM-IO, can also be used with the MD scanner to achieve the same benefits of control. This same scanner can be used to present lumber to the infeed of the planer to maximize the flow automatically.
- The ability of the decks to catch up if they don’t have enough lumber on them is the secret to modulating the flow.
- A simple cable from the scanner to the REM-IO, using RS422 protocol, conveys all the information from each cell. This cable can be up to 1000 feet long so that the REM-IO block can be rail-mounted in the PLC cabinet. The I/O from the block can be combined to reduce the amount of wires connected to the PLC. This is all done through a “True Table” in software.
- The tracking LEDs on each side of the scanner provides an instant troubleshooting guide for the operator. He can watch as the lumber is detected by each cell as the board moves over the scanner.
- The PROX has a direct link to a PC for setting up the parameters of the I/O from the scanner. All programming can be easily accomplished through a True Table to minimize the amount of I/O that the PLC has to handle. This serial link for the Windows interface is a standard RS-232 link setup at a speed of 19200 Baud, 8 bits, No parity and 1 stop bit.
- A global viewing display on the right shows the actual configuration of all cells and outputs. The modification is made by a 5x5 window at the time moving inside the matrix. The Y axis shows the Cells from the Type Prox photocell and the X axis corresponds to the 64 PNP outputs always available on the REM-IO module. The interface is designed for the maximum Cells available (64) but if you use a smaller photocell, any configurations associated with cells that are not physically available on the photocell will have no effect. If you have, for example, an 8-inch Type PROX, only the first 8 lines will be displayed on the 64 LEDs. This window can be moved around the screen by clicking on one of the 8 available arrow bars located around the 5x5 matrix. The movement is only restricted by the edges of the screen. Each time that the window is moved within the matrix, the blue square in the display on the right will move to correspond to the window’s position. In this section, each line corresponds to each individual sensor (cell) starting with cell1 corresponding to the cell nearest the cable connector on the Type Prox photocell itself. Each column represents the output from 1 to 64. Regardless of the number of sensors available on the Type Prox, the number of PNP outputs is fixed at 64. The last column is the Cancel column. If this one were activated, the corresponding cell associated to this line is cancelled. This cell is ignored until it is reactivated. When a cell is cancelled, the complete line is shown in shadow to provide feedback that this line is no longer part of any configuration.
- The PROX scanner can be installed on top or underneath the transfer deck. The field of view is 18-inches (460 mm) and can be reduced if required using an adjustment on the REM-IO.