Motion Control Resources
Industrial Refrigeration Doors
American Control Electronics Posted 08/27/2019
American Control Electronics has a long history of success in industrial and commercial automation. The latest involves an insulated cold storage warehouse door OEM. They were testing a control system that was more complex to commission than they were comfortable with, and were concerned about their costs.
We introduced our PMB series control. With embedded logic on board, we cost reduced the competitive proposal that included a motion controller. Our control enabled the customer to use a lower cost motor …a servo motor was not required to obtain the positioning and control that this application demanded.
The PMB series is part of a family of smart drives that uses a 16-bit microprocessor to monitor inputs (speed potentiometer, enable, direction) and handles power transmission to motors. The PMB series are motor controls with factory programmable PLC-like functionality on board.
This particular solution took a standard PMB series drive and combined it with custom firmware. The customization involved repurposing the drives inputs to monitor four devices; an open/close switch, pneumatic safety edge device, door lock key and a 12 PPR encoder used for speed and position control.
When the open/close switch activates, the door moves toward the open position. Once within a few inches of being fully open, the drive slows the motor to a crawl speed and stops right before reaching the end of travel. A second activation of the open/close input causes the door to perform the same routine in the close direction. No ends of travel limit switches are needed due to the 12 PPR encoder and the drive’s ability to LEARN the encoder count required for a full open and closed cycle. If the pneumatic safety edge device triggered during a closing cycle, the drive will send the door to the full open position. The lock key switch, when in the locked position, will prevent the door from being operated. A second, jumper selectable, routine was written into the micro that allows the same drive to be used with horizontal sliding twin doors…with a different set of operating parameters.
Having a programmable microprocessor in a motor drive and our ability to write custom firmware, are key factors that can help you reduce your purchase cost, BOM complexity, and wiring/assembly time.