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Industrial Automation

P&O Cold Logistics Laverton II Victoria


Other Details

This installation features six stacker cranes, three servicing the chiller pick areas and three servicing the freezer pick areas, and two moderate sized pallet conveyor system.

P&O Cold Logistics later became VersaCold, and, then became Americold.

From our point of veiw the most interesting aspect of this installation was the implementation of the software for the detierer.


The “Device Type Definition” feature was designed with such devices as alignment bars in mind, however the application of this feature to the detierer illustrated its power and the resulting flexibility of the “Conveyor PLC Code Generator” and the “Movement Controller”in general.

The detierer is given an expected number of pallets from the “Movement Controller”which, in this instance, was in turn received from the host computer system. The detierer must then lower its tines, looking for the gaps in pallets, counting down this number. It then inserts its tines in the gap of the second bottom pallet and raises this until it is clear of the bottom pallet. It then waits for the bottom pallet to be conveyed out, before lowering the remainder of the stack and separating out the next load.

Once the detierer device type was defined, all sensors of the device are displayed on the mimic diagram, all alarms are described on the alarm display, and all PLC code is generated by simply entering the name of the device into the table and referencing the conveyor position at which it is located, for each instance of the device.

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Other Details

The conveyor systems incorporates pallet stands at the crane infeeds and outfeeds, double alignment bars, sizing stations, freezer doors, and pallet detierers.

The conveyor systems each service a single forklift infeed, transferring the pallets to a detierer, where individual loads are separated from a stack of up to five loads, and from the detierer to the cranes for storage or for pick area replenishment.

Loads reaching the outfeeds of the six stacker cranes (retrieved from the storage areas) are conveyed to either the forklift outfeed or to another crane for picking.

This was originally developed using MS-DOS. In the wake of upgrading to Microsoft Windows, there was such an outcry from the operators that their Microsoft Windows interface was redesigned so as to mimic the original MS-DOS interface.

Communications between the “Movement Controller”and the cranes is via an infra-red serial link.

Communications between the “Movement Controller”and the host computer system is via FTP/TCP-IP/Ethernet.

All PLCs are Allen-Bradley.

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