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Send to KindlePaint pouch packing is under control
Smith found a simple and inexpensive solution to this problem at a seminar sponsored by a local distributor Barker Electrical (Rockford IL). There he was introduced to a universal logic module from Siemens (Alpharetta GA) called Logo!. The device operates as a rudimentary programmable logic controller that's "downstream" of the main PLC. That is it intercepts an outgoing signal from the PLC processes it according to simple logic instructions and passes on the output signal to the intended actuator cylinder or other device. The logic instructions can be easily entered or modified right on the unit's keypad and LCD display.
"By pressing the module's four arrow keys an 'escape' key and an 'okay' key Testor people can program specific machine functions without having to program the PLC" says Breon.
Testor uses the module for example to provide the flexibility to adjust dwell time in heat-sealing the fitment to the flexible film. Originally cam-actuated there was no way to adjust the dwell time short of physically replacing the cam with a different one for each length of dwell time desired.
Now dwell time is adjusted by a pneumatic cylinder that's electronically rather than mechanically controlled via software in the Logo! module. Making an adjustment is as easy as pressing the keys on the face of the display unit thus signaling the pneumatic cylinder to increase or decrease dwell time.
The logic in the Logo! controller is completely separate from that in the PLC. The signal to heat-seal a fitment still comes from a PLC output. But it is routed through the Logo! module through which Testor can program in a longer or shorter dwell time as it sees fit.
If Testor didn't have the Logo! module then complicated software and a PC would be needed to program the PLC itself. Or a human-machine interface would be required to allow operators to make the change from a touch screen display. A second-generation pouching machine now being designed by Cad/Scan Technologies will indeed incorporate these touches. Its Allen-Bradley PLC will be accessed through a pentium®-powered PC operator interface from CTC Parker Automation (Milford OH). But for today's machine says Smith the Logo! module measuring all of 5"x3.5"x2" and costing about $150 is just the ticket.
"If we need to change an output we program it easily on the keypad" says Smith. "We can even do it on the fly."
Installation was a snap says Smith. "You just plug the module in on a DIN rail."
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